Protective Role of Salicylic Acid and Sodium Nitroprusside Foliar Application Against Copper Stress in Okra (Abelmoschus esculentus)

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At elevated concentrations, copper becomes a toxic element within plants, triggering the generation of oxidative molecules and disrupting enzymatic activities. Salicylic acid (SA) is a plant growth regulator, while sodium nitroprusside (SNP) is a nitric oxide-releasing compound. Both play critical function s in modulating plant metabolism, growth, development, and mechanisms.They also influence gene expression and signaling pathways, with effects that may be either beneficial or detrimental depending on the context. The application of these compounds at appropriate doses significantly contributes to alleviating abiotic stresses in various plant species, particularly by counteracting the toxic effects. In this study, the individual and simultaneous effects of SA (500 µM) and SNP (150 µM), alongside varying concentrations of copper sulfate (600 and 1200 µM), were evaluated on the physiological and morphological responses of the Clemson variety of okra ( Abelmoschus esculentus ) in a hydroponic culture system. The experiments were conducted using a completely randomized design with three replicates per treatment. The results revealed that high copper concentrations reduced growth parameters and essential nutrient levels, while increasing malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and cell death, protein content, proline, soluble carbohydrates, and activities of enzymes, along with copper content in the shoots and roots of okra plants compared to the control. In contrast, foliar application of SA and SNP improved the uptake of essential elements, increasing Mg (up to 41%), Fe (51%), and Zn (50%). It also enhanced antioxidant enzyme activities (67–92%) and significantly reduced copper concentration (58%), MDA content (15%), H₂O₂ levels (26%), and cell death (49%) in the shoots and roots of okra plants. Therefore, based on the results, the individual and combined application of SA and SNP significantly mitigated the adverse effects of copper sulfate stress, improving tolerance of okra plants. According to the findings of this study SA demonstrated a considerably greater effect compared to SNP in in enhancing the resistance of okra plants to copper-induced stress. Biological sciences/Plant sciences Biological sciences/Plant sciences/Plant physiology Biological sciences/Plant sciences/Plant stress responses antioxidant enzymes essential elements nitric oxide oxidative stress Figures Figure 1 Introduction Okra ( Abelmoschus esculentus ) is an annual crop belonging to the Malvaceae family ( 1 ). This species demonstrates high adaptability to a wide range of soil types and is classified as a warm-season vegetable. It thrives best in tropical and subtropical climates, although it is sensitive to cold nighttime temperatures and drought conditions. The natural distribution of okra has been documented in the Middle East and surrounding regions ( 2 , 3 ). Heavy metal (HMs) contamination presents significant environmental and ecological challenges worldwide ( 4 ). The primary issue with HMs arises from their non-biodegradable nature, which, unlike organic contaminants, causes them to persist in the environment. This characteristic renders HMs among the most hazardous groups of environmental pollutants ( 5 ). The toxicity of metals to plants is typically linked to their availability in soils and their chemical form within the soil matrix ( 6 ). The widespread use of copper-based compounds, such as fertilizers, pesticides, and nematicides, has led to extensive copper contamination of agricultural soils ( 7 , 8 ). While copper is a vital micronutrient for plants, its excess accumulation may disrupt photosynthetic and respiratory processes, enzymatic functions, and cellular membrane integrity, leading to membrane damage, reduced metabolism, and, ultimately, cell death ( 9 ). The most prominent impact of copper toxicity is the induction of oxidative stress by stimulating the production of harmful reactive oxygen species (ROS), such as superoxide and hydrogen peroxide. Due to their high reactivity with cellular components, these free radicals cause damage to cells and DNA while inhibiting ATP production. The presence of toxic levels of HMs in the plant environment induces physiological changes that reduce growth potential and, in severe cases, lead to plant mortality. Sensitive plants suffer damage and perish under these conditions, while resistant plants continue to grow and reproduce ( 10 , 11 ). The generation of ROS, induced by oxidative stress from high copper concentrations, can lead to lipid peroxidation of cell membranes. Additionally, plants undergo alterations in their metabolic pathways, affecting the synthesis of essential biomolecules such as proteins and lipids ( 9 , 12 ). HMs-induced stress can interfere with the uptake of essential elements like calcium (Ca), phosphorus (P), magnesium (Mg), and other metals, disrupting the elemental balance in plants ( 13 , 14 ). In response to HMs stress, plants activate antioxidant defense systems, including enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), to mitigate the excessive accumulation of free radicals ( 15 ). Other defense mechanisms plants employ under HMs stress include the accumulation of proline ( 16 ), increased carbohydrate storage ( 13 ), and enhanced protein synthesis ( 17 ). Proline helps protect plants against stress through mechanisms like membrane stabilization, osmotic regulation, and the preservation of enzyme structure and function ( 18 ). Studies by Rather et al. (2020) ( 19 ) demonstrate that the using plant growth regulators, hormones, and other signaling molecules is a key strategy for alleviating copper toxicity in plants. Salicylic acid (SA), a plant growth regulator, is crucial in modulating various stages of plant growth and development, including ion uptake, photosynthesis, germination, enzymatic activity, and nitrogen regulation ( 20 , 21 ). As a naturally occurring phenolic compound, SA effectively mitigates the adverse effects of environmental abiotic stresses ( 22 , 23 ). Numerous studies have shown that SA application alleviates the negative impacts of drought stress ( 24 ), cold stress ( 25 ), salinity stress ( 26 , 27 ), and HMs stress ( 28 , 29 ). Research by Wei et al. (2020)( 30 ) has conclusively demonstrated that SA significantly reduces the toxic effects of HMs stress and, in interaction with nitric oxide, ameliorates the detrimental impacts of HMs toxicity on plants. Nitric oxide (NO) is a vital signaling molecule involved in numerous biochemical and physiological processes in plants, which has led to its classification as a phytohormone. NO acts as a concentration-dependent regulator, participating in key processes such as hypocotyl growth, defense responses, stomatal movement, seed germination, programmed cell death, hypersensitive responses, photosynthesis, growth and development, and phytoalexin production under various stress conditions ( 31 ). Sodium nitroprusside (SNP), an NO donor, is a bioactive molecule that can be applied through irrigation, foliar spraying, or injection into the apoplast of the leaf ( 32 ). It has been reported that SNP effectively mitigates the adverse effects of abiotic stresses, including HMs stress. In recent studies, SNP has been used as a source of NO due to its unique ability to release nitric oxide in plant tissues over an extended period, as well as its cost-effectiveness ( 33 ). Although limited research has been conducted on the effects of foliar application of SNP and SA on enhancing okra plant tolerance to copper sulfate stress, this study investigates their individual and combined effects under copper toxicity. The study primarily focuses on the physiological and biochemical changes in okra plants, alongside their mineral element content, under copper toxicity. The primary aim of this research is to evaluate the enhancement of plant tolerance by stimulating related mechanisms, such as antioxidant activity, while also reducing copper accumulation and limiting its translocation from roots to shoots through the use of SNP and SA. Materials and Methods The plant studied in this research was okra, with seeds of the Clemson Spineless cultivar obtained from the Dutch company Bakker Brothers. Initially, the seeds were disinfected in a 5% sodium hypochlorite solution for 10 minutes, then rinsed several times with tap water and once with distilled water. Four seeds were sown in plastic pots (20 × 30 cm²) filled with perlite, with three independent replicates per treatment, arranged in a completely randomized design. Until the emergence of the first sprout, the pots were irrigated with distilled water and kept in darkness. Upon observing the initial signs of germination, the pots were transferred to a growth chamber with a minimum temperature of 25°C and a maximum of 30°C, 80% relative humidity, and a photoperiod of 14 hours of light and 10 hours of darkness. At the four-leaf stage, the plants were irrigated with Hoagland nutrient solution ( 34 ) at 1/4 and 1/2 strength (each concentration applied for one week), followed by full-strength Hoagland solution alternated with distilled water every other day. At the 6–8 leaf stage, the plants were subjected to foliar application of SNP at 150 µM and SA at 500 µM, each applied separately and also in combination, with treatments repeated twice at a one-week interval. Twenty-four hours after the foliar treatments, the plants were exposed to copper sulfate (CuSO₄) stress at concentrations of 600 and 1200 µM for 14 days. After 35 days (Fig. 1 ) , both shoot and root samples were collected for analysis. Fresh samples were immediately separated and stored at -80°C. The fresh weight of shoots and roots was measured using a digital scale with a precision of 0.001 g. The dry weight of shoots and roots was determined by oven-drying the samples at 75°C for 24 hours. Plant height was measured using a ruler. Determination of malondialdehyde content and hydrogen peroxide levels To determine the MDA content, 0.2 g of fresh shoot or root tissue was thoroughly homogenized in 5 mL of 0.1% (w/v) trichloroacetic acid (TCA). The homogenate was centrifuged (5 min, 10,000 g), and the supernatant was collected. An equal volume of TCA containing 0.5% (w/v) thiobarbituric acid (TBA) was added to the supernatant. The reaction mixture was incubated in a water bath at 95°C for 30 min and then rapidly cooled in an ice bath. After cooling, the samples were centrifuged again (10 min, 10,000 g), and the absorbance of the clear supernatant was recorded at 532 and 600 nm using a spectrophotometer. Finally, the MDA concentration was calculated and expressed as (µmol g − 1 FW) ( 35 ). Additionally, H₂O₂ levels were measured by homogenizing 0.5 g of shoot and root tissues in 0.1% TCA. The resulting homogenate was mixed with potassium phosphate buffer and potassium iodide to form the reaction mixture. Absorbance was then recorded at 390 nm ( 36 ). Determination of Cell Death To assess cell death, three 1-cm segments from the root tips of copper sulfate-treated plants and control samples were immersed in a 0.025% Evans blue solution for 30 minutes to specifically stain non-viable cells. Excess dye was removed by thoroughly washing the samples with distilled water for 15 minutes. To extract the dye bound to dead cells, the samples were homogenized in 1 mL of 50% methanol and incubated in a water bath at 50°C for 15 minutes. After centrifugation at 14,000g, the percentage of cell death was determined by measuring the absorbance of the supernatant at a wavelength of 600 nm and comparing it to the untreated control sample ( 37 ). Determination of Soluble Sugar, Proline and Total Soluble Protein Content In this study, soluble sugar content was quantified in 0.5 g samples of root and shoot tissues using the phenol-sulfuric acid method ( 38 ). Proline content was determined according to a previously established protocol with slight modifications ( 39 ). For this, 0.2 g of leaf or root tissue was homogenized in 3 mL of 3% sulfosalicylic acid. The homogenate was then mixed with ninhydrin reagent and glacial acetic acid, followed by incubation at 100°C for 1 hour. The reaction mixture was rapidly cooled in an ice bath, after which 4 mL of toluene was added. The absorbance of the upper organic phase was measured at 520 nm using a spectrophotometer. Total soluble protein content was measured using the Bradford method ( 40 ), and the resulting protein extract was subsequently used for the determination of antioxidant enzymes activities. Determination of Antioxidant Enzymes Activities The activities of catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7), and superoxide dismutase (SOD, EC 1.15.1.1) were determined following the method described by Chance and Maehly ( 41 ). CAT activity was assessed by measuring the decrease in absorbance at 240 nm due to the decomposition of H₂O₂, while POD activity was determined by monitoring the oxidation of guaiacol at 470 nm. SOD activity was evaluated based on its ability to inhibit the photoreduction of nitroblue tetrazolium (NBT) at 560 nm ( 42 ). Enzyme activities were expressed as units per milligram of protein per minute. Determination of Elemental Content The total elemental content was assessed using a modified Sagner et al. (1998) ( 43 ) method. Plant root and shoot samples were dried at 70°C for 72 hours, and 0.5 g of each was digested in 10 mL of 65% (w/v) ultrapure nitric acid (Merck). After digestion, the volume was adjusted to 50 mL with deionized water, and concentrations of Cu, Fe, Mg and Zn were measured via atomic absorption spectrophotometry (AA6200 Shimadzu). To assess the translocation of Cu from roots to shoots, the translocation factor (TF) was calculated based on the following Eq. (44). $$\:TF=\frac{Cu\:concentration\:in\:the\:shoots}{Cu\:concentration\:in\:the\:roots}$$ The results of plant growth indices (fresh weight, dry weight, shoot length, and root length) Copper stress significantly reduced the fresh and dry weights of shoots and roots, as well as their lengths, compared to the control, with the most pronounced effects at 1200 µM. Cu stress also led to a significant reduction in shoot and root lengths, highlighting its inhibitory effect on plant growth. At 1200 and 600 µM Cu, shoot fresh weight decreased by 2.41- and 3.77-fold, root fresh weight by 2.16- and 3.84-fold, shoot dry weight by 2.22- and 7.06-fold, and root dry weight by 2.46- and 6.55-fold, respectively. However, applying SA and SNP, alone or combined with Cu, significantly enhanced growth indices under stress. The application of SA and SNP alleviated Cu-induced growth inhibition and improved shoot and root development. The greatest improvements in shoot fresh and dry weights were observed in Cu1200 + SA (31.63%) and Cu1200 + SA + SNP (50.03%), respectively, while root fresh and dry weights peaked in Cu600 + SA + SNP (36.92%) and Cu1200 + SA (63.46%), respectively, compared to Cu-stressed plants without SA or SNP (Table 1 ). Table 1 Interactive Effects of Copper Stress, SA, and SNP on Growth Parameters in Okra Treatments Root fresh weight/plant (g) Root dry weight/plant (g) Root length (cm) Shoot length (cm) Shoot fresh weight/plant (g) Shoot dry weight/plant (g) Control 8.32 ± 0.28b 0.83 ± 0.020a 28.2 3 ± 0.23a 40.16 ± 1.16 ab 13.75 ± 0.55c 2.93 ± 0.21 a 500 µM SA 9.29 ± 0.15a 0.81 ± 0.0 4a 26.43 ± 0.23b 40. 83 ± 1.0 ab 16.14 ± 0.49ab 2.83 ± 0.0 8a 150 µM SNP 8.25 ± 0.14b 0.73 ± 0.024a 25.25 ± 0.25c 39.66 ± 0.69b 15.19 ± 0.87 abc 3.18 ± 0.13a SA + SNP 8.95 ± 0.36ab 0.93 ± 0.02 a 29.3 ± 0.3a 42.16 ± 0.92 a 16.75 ± 0.55 a 3.15 ± 0.25 a 600 µM CuSO 4 3.85 ± 0.35 cd 0.33 ± 0.02 d 20 ± 0.57e 25.63 ± 0.31 e 9.73 ± 0.87 de 1..32 ± 0.12c 600 µM CuSO 4 +SA 4.31 ± 0.29c 0.55 ± 0.023b 22.59 ± 0.30d 28.33 ± 0.61 d 14.23 ± 1.07bc 1.73 ± 0.05 bc 600µM CuSO 4 + SNP 4.58 ± 0.46 c 0.43 ± 0.023c 25.96 ± 0.39bc 29.76 ± 0.62 d 11.22 ± 0.58d 1.62 ± 0.19bc 600µMCuSO 4 + SA + SNP 4.66 ± 0.24 c 0.43 ± .0.028c 26.67 ± 0.33b 32.23 ± 0.52c 13.73 ± 0.38c 1.92 ± .0.03b 1200 µM CuSO 4 1.16 ± 0.20 e 0.12 ± .0.030e 14.96 ± 0.20g 16.80 ± 0.73h 3.64 ± 0.30 f 0.416 ± .0.04d 1200µMCuSO 4 + SA 3.40 ± 0.21d 0.26 ± 0.012d 18.5 ± .0.76 f 23.96 ± .0.54ef 8.18 ± .0.46e 0.649 ± 0.04d 1200µMCuSO 4 + SNP 3.03 ± 0.29d 0.18 ± 0.020e 18 ± 0.28 f 20.6 3 ± 0.63 g 4.69 ± 0.64 f 0.569 ± 0.05d 1200µMCuSO 4 + SA + SNP 4.33 ± 0.23c 0.34 ± 0.024d 22.5 ± 0.28d 23..13 ± 0.40f 5.32 ± 0.59 f 0.044 ± 0.12d Three different letters indicate a significant difference at the 5% level based on Duncan's test. Results of Malondialdehyde Content, Hydrogen Peroxide Levels, and Cell Death This study revealed that Cu stress significantly increased H₂O₂ levels and MDA content in shoots and roots, peaking in the 1200 µM Cu treatment and lowest in the control. However, applying SA and SNP, alone or combined, significantly lowered these parameters in stressed plants. The greatest H₂O₂ reduction occurred in the Cu600 + SA treatment (26.93% in shoots), Cu600 + SA + SNP (18.79% in roots), while MDA decreased most in Cu600 + SA + SNP for shoots (15.42%) and Cu600 + SA for roots (14.99%) compared to Cu-only treatments. Under non-stress conditions, SA, SNP, or their combination showed no significant impact on H₂O₂ or MDA levels ( Tables 2 and 3 ). Increasing Cu in the nutrient solution elevated root cell death, but SA and SNP, applied individually or in combination, mitigated this effect. The highest cell death was observed in the 1200 µM Cu treatment, while SA and SNP proved effective across various Cu concentrations. The combination of SA and SNP in the CuSO 4 (600 µM) + SA treatment resulted in the reduction (45%). Under non-stress conditions, these compounds had no effect ( Tables 3 ). Results of Soluble Sugar, Proline and Protein Content The analysis of copper stress effects on okra showed a significant increase in soluble carbohydrate content in both shoot and root tissues compared to the control, with the highest increase observed in the 1200 µM copper treatment. The use of SA, SNP, and their combination under both copper stress levels resulted in a significant reduction in carbohydrate content. The greatest reduction was observed in the CuSO₄ (600 µM) + SA treatment, with decreases of 10.04% in the shoots and 9.70% in the roots compared to copper treatments alone. When SNP was co-applied with copper, carbohydrate content decreased further, with reductions of 4.77% and 5.94% in the shoots and 7.08% and 6.15% in the roots under Cu 600 + SNP and Cu 1200 + SNP treatments, respectively. Under non-stress conditions, SA and SNP treatments had no effect on soluble carbohydrate content in the shoots. However, in the roots, SNP treatment significantly increased carbohydrate content in the 600 µM treatment ( Tables 2 and 3 ). Our research findings demonstrated that copper stress led to an increase in proline content in both the shoots and roots of the plant. The highest proline accumulation was observed in the shoots of the 1200 µM Cu treatment, showing a sixfold increase compared to the control. The application of SA reduced proline content in okra plants under copper stress. However, SNP treatment, in combination with 600 and 1200 µM Cu stress, significantly increased proline content in the shoots by 81.96% and 85.51%, respectively, and in the roots by 37.53% and 47.31% compared to the control group. Under non-stress conditions, SNP application did not affect proline content ( Tables 2 and 3 ). The results of the (Cu) effect assessment revealed that protein content significantly increased in shoots by 34.82% and 59.95% at 600 and 1200 µM Cu treatments, respectively, and by 47.47% in roots at 1200 µM Cu, while no significant change was observed in roots at 600 µM Cu. The application of (SA) and (SNP), individually or in combination, further increased protein content in shoots and roots under Cu stress. The greatest increases were recorded in the Cu1200 + SA + SNP treatment for shoots (63.65%) and in the Cu1200 + SNP treatment for roots (57.63%). Under non-stress conditions, protein content in treated plants also rose compared to the control ( Tables 2 and 3 ). Table 2 Interactive Effects of Copper Stress, SA, and SNP on MDA Content, H₂O₂ Levels, and Proline, Sugar, and Protein Content in Shoot Treatments MDAShoot (µmol/g FW) H 2 O 2 Shoot (µmol/g FW) Soluble Sugar Shoot (mg/g FW) Proline Shoot (nmol/g FW) Total Proteins Shoot (mg/g FW) Control 0.445 ± 0.022e 0.95 ± 0.03e 32.05 ± 1.05f 0.903 ± 0.071d 7.22 ± 0.415f 500 µM SA 0.454 ± 0.019e 1.03 ± 0.04 e 32.40 ± 0.30f 1.31 ± 0.151d 9.39 ± 0.231e 150 µM SNP 0467 ± 0.020e 1.08 ± 0.07 e 34.80 ± 0.30e 1.053 ± 0.103d 9.12 ± 0389e SA + SNP 0.454 ± 0.012e 0.99 ± 0.07 e 32.87 ± 0.416f 0.76 ± 0.069d 9.45 ± 0.410e 600 µM CuSO 4 0.662 ± 0.0402c 2.3 ± 0.013c 40.88 ± 0.458c 4.14 ± 0.081b 11.08 ± 0.289d 600 µM CuSO 4 +SA 0.595 ± 0.024 cd 1.07 ± 0.05d 36.91 ± 0.471d 3.07 ± 0.133c 13.22 ± 0.170 c 600µM CuSO 4 + SNP 0.616 ± 0.035 cd 1.92 ± 0.09d 38.45 ± 0.54d 5.01 ± 0.156b 12.68 ± 0.612c 600µMCuSO 4 + SA + SNP 0.573 1 ± 0.028d 1.84 ± 0.11 d 38.38 ± 0.428d 4.45 ± 0.223b 13.49 ± 1.075c 1200 µM CuSO 4 0.949 ± 0.0201a 3.12 ± 0.10a 49.82 ± 0.858a 5.75 ± 0.138a 18.47 ± 0.252 b 1200µMCuSO 4 + SA 0.848 ± 0.0287b 2.51 ± 0.17bc 45.08 ± 0.103b 4.49 ± 0.248b 18.13 ± 0.470 b 1200µMCuSO 4 + SNP 0.858 ± 0.204b 2.76 ± 0.11b 47.44 ± 0.585b 6.23 ± 0.107a 18.13 ± 0.967 b 1200µMCuSO 4 + SA + SNP 0.848 ± 0.0315b 2.62 ± 0.14 bc 46.59 ± 0.409b 6.05 ± 0.285a 19.87 ± 0.537a Three different letters indicate a significant difference at the 5% level based on Duncan's test. Table 3 Interactive Effects of Copper Stress, SA, and SNP on MDA, H₂O₂, Proline, Sugar, Protein Content, and Cell Death Percentage in Roots Treatments MDA Root (µmol/g FW) H 2 O 2 Root (µmol/g FW) Cell death Root (% of control) Soluble sugar Root (mg/g FW) Proline Root (nmol/g FW) Total Proteins Root (mg/g FW) Control 0.209 ± 0.0012 e 0.087 ± 0.030d 91.35 ± 7.42g 23.94 ± 0.408 gh 4.51 ± 0.265f 2.97 ± 0.433f 500 µM SA 0.198 ± 0.0013e 0.072 ± 0.073d 109.50 ± 8.79g 22.96 ± 0.577g 4.84 ± 0.099 def 4.01 ± 0.217d 150 µM SNP 0.201 ± 0.009e 0.087 ± 0.004d 134.73 ± 3.93g 22.55 ± 0.360h 5.23 ± 0.315de 3.37 ± 0.301ef SA + SNP 0.195 ± 0.0009e 0.085 ± 0.008d 96.56 ± 16.21 g 24.08 ± 0.451gh 4.53 ± 0.188ef 4.23 ± 0.304de 600 µM CuSO 4 0.2 95 ± 0.014c 0.138 ± 0.003b 398.52 ± 10.10c 28.21 ± 0.927cde 6.59 ± 0.223c 3.45 ± 0.422ef 600 µM CuSO 4 +SA 0.251 ± 0.0121d 0.121 ± 0.003c 212.23 ± 20.20f 25.38 ± 0.508fg 5.291 ± 0.118d 3.31 ± 0.238ef 600µM CuSO 4 + SNP 0.265 ± 0.0128 cd 0.123 ± 0.002c 319.40 ± 24.59de 26.48 ± 0.608ef 7.346 ± 0.192b 4.23 ± 0.158de 600µMCuSO 4 + SA + SNP 0.281 ± 0.009cd 0.112 ± 0.006c 274.26 ± 21.09ef 27.10 ± 0.459def 5.55 ± 0.248d 4.47 ± 0.307d 1200 µM CuSO 4 0.414 ± 0.0138a 0.163 ± 0.003a 736.07 ± 48.90a 32.76 ± 1.240a 8.212 ± 0.164a 5.66 ± 0.423c 1200µMCuSO 4 + SA 0.356 ± 0.008b 0.144 ± 0.002b 372.57 ± 30.71cd 28.64 ± 0.266bcd 7.48 ± 0.280b 6.68 ± 0.207b 1200µMCuSO 4 + SNP 0.379 ± 0005b 0.148 ± 0.005b 537.13 ± 23.28b 30.44 ± 0.526b 8.564 ± 0.262a 7.02 ± 0.408a 1200µMCuSO 4 + SA + SNP 0.378 ± 0.011 b 0.144 ± 0.004b 400.84 ± 21.09c 29.87 ± 0.440bc 7.984 ± 0.248ab 6.49 ± 0.239ab Three different letters indicate a significant difference at the 5% level based on Duncan's test. Results of Antioxidant Enzymes Activity According to the results obtained from Table 4 , SOD enzyme activity increased by 35.55% and 53.59% in the shoots and by 73.93% and 89.52% in the roots under 600 and 1200 µM Cu treatments, respectively, compared to the control. Foliar spraying of SA and SNP, either individually or in combination, further enhanced SOD activity under Cu stress. The highest SOD activity was observed in the Cu1200 + SA + SNP treatment, with increases of 67.11% in shoots and 92.17% in roots compared to the control. With increasing Cu concentrations, POD enzyme activity rose by 59.18% and 84.17% in shoots and by 73.44% and 84.79% in roots. Application of SA and SNP, either separately or together, significantly enhanced POD activity in Cu-treated plants compared to the control. The greatest increases were recorded in the Cu1200 + SA + SNP treatment for shoots 88.40% and in the Cu1200 + SA treatment for roots 86.80%. In non-stress conditions, foliar application of SA and SNP had no significant effect on POD activity in shoots; however, in roots, the combined SA + SNP treatment resulted in an increased POD activity. The results for CAT enzyme activity indicated increases at both Cu levels, with rises of 29.68% and 57.94% in shoots and 19.54% and 27.61% in roots compared to the control. In plants subjected to foliar application of SA and SNP (either individually or in combination), CAT activity was higher compared to plants exposed to Cu stress alone. The highest increases in CAT activity were observed in the Cu1200 + SA + SNP treatment, with enhancements of 67.04% in shoots and 67.02% in roots relative to the control ( Table 4 ) . Table 4 Interactive Effects of Copper Stress, SA, and SNP on Antioxidant Enzyme Activity in Shoots and Roots Treatments SOD Shoot unit mg − 1 protein CAT Shoot unit mg − 1 protein POD Shoot unit mg − 1 protein SOD Root unitmg 1 protein CAT Root unit mg − 1 protein POD Root unit mg − 1 protein Control 12.63 ± 1.33e 18.01 ± 0.533i 0.789 ± 0.058g 5.46 ± 0.417g 11.71 ± 0.572h 1.47 ± 0.073f 500 µM SA 11.93 ± 0.481f 20.83 ± 0.440 h 0.997 ± 0.0827g 7.48 ± 0.736 g 12.50 ± 0.449gh 1.82 ± 0.231ef 150 µM SNP 10.83 ± 1.03f 20.98 ± 0.768 h 0.799 ± 0.085 fg 5.92 ± 0.499g 14.39 ± 0.811fg 1.59 ± 0.305f SA + SNP 14.00 ± 0.576 e 21.44 ± 0.446h 1.03 ± 0.136f 5.66 ± 1.94g 15.14 ± 0.751f 3.06 ± 0.408e 600 µM CuSO 4 19.61 ± 1.92d 25.62 ± 0.881g 1.93 ± 0.211e 19.81 ± 1.66f 19.54 ± 0.443e 5.561 ± 0.149d 600 µM CuSO 4 + SA 22.78 ± 1.37d 28.35 ± 0.548f 2.98 ± 0.292d 29.75 ± 1.87e 22.98 ± 1.09d 6.708 ± 0.733c 600µM CuSO 4 + SNP 26.93 ± 0.885c 30.94 ± 0.580ef 2.88 ± 0.219d 28.29 ± 2.60e 24.51 ± 0.846d 6.65 ± 0.414c 600µMCuSO 4 + SA + SNP 29.32 ± 0.735bc 32.01 ± 1.01ef 3.28 ± 0.374d 37.39 ± 1.55d 24.17 ± 0.554d 7.60 ± 0.210c 1200 µM CuSO 4 27.23 ± 1.51c 42.84 ± 1.31d 5.18 ± 0.313c 51.17 ± 3.39c 27.61 ± 1.05c 9.71 ± 0.182b 1200µMCuSO 4 + SA 32.18 ± 2.11b 45.88 ± 0.843c 6.12 ± 0.351ab 59.29 ± .2.29b 32.96 ± .1.03b 11.197 ± 0.678a 1200µMCuSO 4 + SNP 36.21 ± 1.62a 51.15 ± 1.78b 6.02 ± 0.239b 60.58 ± 2.26b 33.78 ± 0.874ab 10.39 ± 0.232ab 1200µMCuSO 4 + SA + SNP 38.43 ± 1.71a 54.67 ± 1.20a 6.80 ± 0.187a 68.48 ± 2.20a 35.51 ± 0.572a 11.14 ± 0.400a Three different letters indicate a significant difference at the 5% level based on Duncan's test. Results of Elemental Levels (Cu, Zn, Mg, and Fe) and TF The results showed that Cu stress reduced Zn, Mg, and Fe contents in the shoots and roots of okra plants at 600 and 1200 µM Cu levels. However, applying SA and SNP significantly elevated these elements in specific treatments. The largest increases were recorded for Zn in the Cu600 + SA + SNP treatment (50.40%) and Mg in the Cu600 + SA treatment (41.78%). Likewise, Fe content increased in the Cu600 + SA (38.37%) and Cu600 + SNP (51.38%) treatments. In contrast, Cu content in plants under 1200 µM Cu stress rose substantially compared to the control, yet SA and SNP application significantly lowered Cu levels in shoots (58.46%) and roots (73.42%) in the Cu600 + SA + SNP treatment. Data of Table 5 indicated that the translocation factor (TF) decreased with higher Cu concentrations, due to Cu-induced stress and reduced plant ability to transfer Cu from roots to shoots. These results suggest that okra is not a hyperaccumulator under Cu stress, as its TF remained below 1 ( Tables 5 and 6 ). Table 5 Interactive Effects of Copper Stress, SA, and SNP on Elemental Content in Okra Shoots Treatments Mg Shoot (mg/g DW) Fe Shoot (mg/g DW) Cu Shoot (µg/g DW) Zn Shoot (mg/g DW) TF Control 4.29 ± 0.065b 0.151 ± 0.005a 36 ± 1.616g 0.028 ± 0.0003a 0.393 ± 0.05a 500 µM SA 4.66 ± 0.140a 0.152 ± 0.006 a 35.73 ± 2.082g 0.029 ± 0.0007a 0.273 ± 0.023b 150 µM SNP 4.63 ± 0.110a 0.147 ± 0.003a 36.8 ± 1.890fg 0.028 ± 0.0007a 0.276 ± 0.027b SA + SNP 4.74 ± 0.14a 0.153 ± 0.008a 38.13 ± 3.014gf 0.030 ± 0.0004a 0.273 ± 0.039b 600 µM CuSO 4 2.23 ± 0.109d 0.07 ± 0.005 d 130.6 ± 6.150d 0.018. ±0.0004de 0.206 ± 0.012 bc 600 µM CuSO 4 + SA 3.84 ± 0.072c 0.11 ± 0.002b 99.6 ± 11.60e 0.021 ± 0.0004bc 0.161 ± 0.02c 600µM CuSO 4 + SNP 3.56 ± 0.104c 0.12 ± 0.007 b 54.26 ± 2.755gf 0.020 ± 0.0003bcd 0.202 ± 0.005 bc 600µMCuSO4 + SA + SNP 3.62 ± 0.096c 0.12 ± 0.007b 65.33 ± 5.871f 0.023 ± 0.0008b 0.182 ± 0.023 bc 1200 µM CuSO4 1.69 ± 0.065e 0.052 ± 0.003 e 265.0 ± 8.340a 0.014 ± 0.0004f 0.206 ± 0.003bc 1200µMCuSO4 + SA 2.08 ± 0.080d 0.108 ± 0.006bc 182.5 ± 13.33c 0.019 ± .0.0002cde 0.156 ± 0.012c 1200µMCuSO4 + SNP 2.293 ± 0.153d 0.092 ± 0.008cd 224.1 ± 12.66b 0.016 ± 0.0003ef 0.220 ± 0.015 bc 1200µMCuSO4 + SA + SNP 2.382 ± 0.167d 0.096 ± 0.006c 203.2 ± 20.38bc 0.018 ± 0.0003cde 0.203 ± 0.017bc Three different letters indicate a significant difference at the 5% level based on Duncan's test. Table 6 Interactive Effects of Copper Stress, SA, and SNP on Elemental Content in Okra Roots Treatments Mg Root (mg/g DW) Fe Root (mg/g DW) Cu Root (µg/g DW) Zn Root (mg/g DW) Control 2.86 ± 0.035b 1.51 ± 0.059a 93.73 ± 7.62g 0.047 ± 0.0005a 500 µM SA 3.183 ± 0.084a 1.151 ± 0.063a 130.4 ± 6.34g 0.045 83 ± 0.005a 150 µM SNP 3.11 ± 0.109ab 1.47 ± 0.034a 135.7 ± 10.55g 0.047.66 ± 0.0018a SA + SNP 3.21 ± 0.087a 1.57 ± 0.10a 142.5 ± 8.873g 0.048.16 ± 0.0012a 600 µM CuSO 4 2.10 ± 0.052de 0.864 ± 0.036c 628.8 ± 9.75d 0.024.63 ± 0.0016cd 600 µM CuSO 4 + SA 2.34 ± 0.116cd 1.10 ± 0.031b 595 ± 66.36 d 0.035 ± 0.001b 600µM CuSO 4 + SNP 2.59 ± 0.117c 1.07 ± 0.059b 269.8 ± 22.28f 0.029 ± 0.001cd 600µMCuSO4 + SA + SNP 2.38 ± 0.167cd 1.20 ± 0.074b 360 ± 16.16e 0.029 ± 0.003c 1200 µM CuSO4 1.55 ± 0.083f 0.438 ± 0.061e 1290.9 ± 40.31a 0.017 ± 0.0008e 1200µMCuSO4 + SA 1.87 ± 0.037e 0.695 ± 0.074cd 1151 ± 20.24b 0.026 ± .0.0005cd 1200µMCuSO4 + SNP 1.82 ± 0.061e 0.596 ± 0.073de 1025 ± 47.20c 0.027 ± 0.0004d 1200µMCuSO4 + SA + SNP 1.91 ± 0.058e 0.689 ± 0.070cd 878 ± 11.93c 0.026 ± 0.001cd Three different letters indicate a significant difference at the 5% level based on Duncan's test Discussion Copper exposure substantially reduced growth, height, and both the fresh and dry biomass of shoots and roots in okra plants. These detrimental effects arise from the heightened sensitivity of roots to copper toxicity, as they are the first organs exposed to contaminants and consequently sustain the greatest damage. The presence of copper in the rhizosphere causes morphological alterations in the root apex, leading to shorter and thicker roots. Additionally, copper stress impairs root growth and the absorption of water and nutrients by decreasing the rate of mitotic division ( 45 , 46 ). Comparable effects were observed in Indian jute ( Corchorus capsularis L.) and Aegilops tauschii under copper stress ( 47 , 48 ). Foliar application of SA enhanced plant growth and markedly improved the fresh and dry biomass of shoots and roots in okra, which is consistent with similar findings observed in bean and Salvia officinalis L. under copper stress ( 49 , 50 ). SA likely promotes vegetative growth by stimulating indole acetic acid (IAA) and gibberellin synthesis, while boosting stem and root development through improved nutrient uptake ( 51 ). Foliar SNP mitigated copper toxicity, enhancing okra growth and yield. SNP’s role in alleviating HM stress and improving growth was also noted in perennial ryegrass and Chinese cabbage under cadmium toxicity ( 52 , 53 ). Hajihashem et al. (2022) found that combined SA + SNP treatment enhanced plant growth by increasing metabolite synthesis and carbon fixation, while stimulating growth via cell wall acidification ( 54 ). In this study, simultaneous SNP + SA application increased okra growth, biomass, and height. In this study, copper toxicity markedly elevated the levels of H₂O₂, MDA, and cell death in both the shoots and roots of okra plants. Despite higher Cu accumulation in the roots, the shoot tissues exhibited greater MDA content, indicating their heightened sensitivity to Cu-induced oxidative damage. Similar increases in H₂O₂ and MDA under copper stress have been reported in Boehmeria nivea ( 55 ) and Brassica juncea ( 56 ), along with enhanced cell death in pea ( Pisum sativum ) roots ( 57 ). The application of 500 and 150 µM levels of SA and SNP significantly reduced cell death, MDA, and H₂O₂ levels in both the shoots and roots of okra plants exposed to copper toxicity. These findings highlight the effectiveness of these treatments in alleviating copper-induced oxidative stress. SA is believed to confer protection by inhibiting lipid peroxidation, maintaining membrane integrity, and enhancing the antioxidant defense system ( 58 ). Similar protective effects of SA have been reported in cotton under copper stress ( 59 ), in soybean roots under aluminum toxicity ( 60 ), and in Canola subjected to arsenic stress ( 61 ), where reductions in MDA, H₂O₂, and cell death were observed. SNP functions as a signaling molecule that regulates the expression of antioxidant defense genes, thereby enhancing the production of enzymes that neutralize ROS. This action contributes to reduced oxidative damage, improved membrane stability, and a decrease in cell death ( 62 ). These findings align with similar results observed in plants such as soybean ( 63 ) and rice ( 64 ) under HMs stress. Additionally, the simultaneous application of SA and SNP in safflower under zinc stress led to a significant reduction in H₂O₂ and MDA levels in both the roots and shoots of okra ( 65 ). Under copper stress conditions, okra plants exhibited an effective adaptive response by increasing proline and soluble sugar content in both roots and shoots, with a more prominent increase observed in the roots. Proline accumulation, as an osmotic and oxidative stress protectant ( 16 ), has been previously reported in Boehmeria nivea ( 55 ) and Linum usitatissimum ( 66 ). Additionally, an elevation in soluble carbohydrates, contributing to osmotic osmotic regulation and carbon storage, has been observed in Spartina alterniflora under copper stress ( 67 , 68 ). The increase in soluble sugars may result from factors such as growth cessation, breakdown of polysaccharides like starch, non-photosynthetic sugar synthesis, and reduced exchange of photosynthetic products between plant parts. These results underscore the essential role of these compounds in plant adaptation to HMs stress( 13 ). The evaluation of individual and joint treatments of SA and SNP in the roots and shoots of okra under copper stress, compared to the control, showed an increase in proline and soluble sugars. However, a noticeable decline in osmolyte levels under SA treatment was observed compared to the stress levels. This decrease in proline in the SA treatment is likely due to the fact that, in the presence of SA, there is less need for free proline as a stress protectant. A reduction in soluble sugars in plants such as Oryza sativa L. (Rice) ( 69 ) and Helianthus annuus L. ( 70 ) treated with SA under copper stress has been reported. Ahmad et al. (2016) ( 71 ) indicated that NO helps maintain cell turgor and water retention in plants by stimulating the accumulation of osmotic regulators, including proline and soluble sugars, thereby enhancing plant resilience against environmental stressors. In our study, the separate and combined application of SNP to the roots and leaves of okra under copper stress resulted in increased proline and soluble carbohydrates levels relative to the control. Our findings are consistent with those reported for tomato ( Solanum lycopersicum ) ( 72 ). The increase in protein content in the shoot and root organs of okra plants under copper stress may be attributed to the compensatory synthesis of proteins that have been inactivated by binding to HMs, or to the enhanced production of stress-related proteins such as heat shock proteins (HSPs) and enzymes involved in antioxidative defense ( 73 ). This result has similarly been documented for wheat variety ( Triticum aestivum L.) ( 17 ). In the present study, both separate and combined applications of SNP and SA led to an increase in protein content in the shoot and root organs of okra plants under copper stress. This increase seems to be related to the role of SA in strengthening the antioxidant system and membrane protection, in addition to the effect of NO released from SNP in reducing oxidative stress and maintaining cellular redox homeostasis. The results are consistent with findings reported in Oryza sativa L. ( 64 ). Antioxidants, both enzymatic and non-enzymatic, are integral components of the plant defense system, developed to eliminate excess ROS and preserve cellular redox homeostasis ( 74 , 75 ). In the present study, copper stress led to an increased activities of CAT, POD, and SOD in both shoot and root tissues of okra, which is consistent with findings reported for Hibiscus cannabinus L. under similar conditions ( 76 ). Similarly, a study by Wang et al. (2024) revealed that copper toxicity triggered a significant increase in antioxidant enzyme activity in both the shoots and roots of Aegilops tauschii ( 48 ). Exposure of okra plants to SA and SNP, either individually or in combination, significantly enhanced the activity of antioxidant enzymes (CAT, POD, and SOD) in both shoot and root tissues under copper-induced stress. This enhancement was particularly pronounced in the combined Cu + SA treatment, highlighting the protective role of SA in reducing oxidative stress induced by HMs exposure. Previous studies have also demonstrated that SA improves the efficiency of the plant’s antioxidant system by suppressing ROS generation and mitigating lipid oxidative stress ( 77 ), in addition to inducing antioxidant enzymes or regulation of their gene expression ( 78 ). A similar increase in antioxidant enzyme activity in response to SA treatment has also been reported in wheat ( 79 ). SNP as a NO donor enhances the plant's defense mechanisms and mitigates damage caused by various abiotic factors by inducing the expression of antioxidant-related genes ( 80 ). In the present study, SNP application in okra under copper stress led to an increase in antioxidant enzyme activity, a response that has also been observed in sorghum under copper stress ( 72 ). In our study, the simultaneous application of SA and SNP led to an increase in antioxidant enzyme activity in okra plants, a finding that aligns with the results reported by Mostofa et al. (2019) ( 81 ) in rice plants under cadmium stress. This current research demonstrated that copper accumulation in okra plants under copper stress was significantly greater in the roots compared to the shoots. This indicates a slow movement of copper upward from roots to shoots and suggests that okra is not a hyperaccumulator species. These findings are consistent with those of Ibrahim (2017) ( 82 ) who reported greater copper accumulation in the root system than in the stem tissues of Gynura procumbens (Lour). Furthermore, in okra, increasing copper concentrations in the growth medium led to a reduction in essential nutrients such as Mg, Zn and Fe likely due to competitive uptake mechanisms. These observations align with those of Es-sbihi et al. 2020 ( 50 ), who investigated Salvia officinalis under copper stress. In this research, foliar application of SA, SNP and their combination SA + SNP significantly increased the content of Mg, Zn, and Fe while reducing Cu accumulation in the roots and shoot parts of okra plants under Cu stress. These results indicate the inhibitory effect of SA and SNP on the process of Cu uptake and transfer to different plant parts. Moreover, treatment with SA and SNP reduced Cu toxicity by decreasing the transfer of this element and enhancing antioxidant enzyme activity in the plant. Similar results have been confirmed in cotton ( Gossypium hirsutum ) and rice ( 59 , 83 ). A research by Bai et al. 2015 ( 84 ) showed that SA treatment increased the levels of Mg, Zn, Mn, and Fe in Lolium perenne under cadmium stress. It has been reported that SNP reduced heavy metal accumulation and increased the levels of Fe, Mn, and Zn in soybean plants under mercury stress ( 63 ). This effect was likely due to an increase in internal NO content, which activates membrane transporters, leading to metal removal and increased absorption of essential mineral elements ( 85 ). In another research, it was confirmed that the combination of SA and SNP significantly increased the levels of essential elements such as K, Ca, Zn, Fe, and Mn in rose plants under alkaline stress ( 86 ). Conclusion This study demonstrated that foliar application of SA and SNP whether applied individually or in combination significantly enhanced the tolerance of okra plants to copper stress. These protective effects were associated with reduced copper accumulation in plant tissues, mitigation of copper-induced oxidative stress, and improved regulation of nutrient uptake. Treatment with SA and SNP led to a decrease in cellular damage markers (e.g., MDA and H₂O₂), preservation of membrane integrity, enhancement of the antioxidant defense system, and improved uptake of essential nutrients. Overall, the results of the comparative analysis indicated that SA was more effective than SNP in alleviating copper toxicity and enhancing okra’s physiological tolerance. Declarations Approval for plant experiments All experimental procedures involving plants were carried out in accordance with institutional, national, and international regulations and ethical standards. Data availability The datasets used and /or analyzed during the current study are available from the corresponding author on reasonable request. References Dantas, T. L., Alonso Buriti, F. C., & Florentino, E. R. (2021). 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(2006) Response of barley grains to the interactive effect of salinity and salicylic acid. Plant Growth Regul. 45: 215-224. http://doi.org/10.1007/s10725-005-4928-1. Ahmad, P., Abdel Latef, A. A., Hashem, A., Abd_Allah, E. F., Gucel, S., & Tran, L. S. P. (2016). Nitric oxide mitigates salt stress by regulating levels of osmolytes and antioxidant enzymes in chickpea. Front. Plant Sci. 7, 347. https://doi.org/10.3389/fpls.2016.00347. Ahmad, P., Ahanger, M. A., Alyemeni, M. N., Wijaya, L., & Alam, P. (2018). Exogenous application of nitric oxide modulates osmolyte metabolism, antioxidants, enzymes of ascorbate-glutathione cycle and promotes growth under cadmium stress in tomato. Protoplasma, 255 , 79-93. https://doi.org/10.1007/s00709-017-1132-x. Koentjoro, Y., Purwanto, E., & Purnomo, D. (2021). The role of silicon on content of proline, protein and abscisic acid on soybean under drought stress, In: IOP Conference Series: Earth and Environmental Science. IOP Publishing, p. 12086. http://doi.org/10.1088/1755-1315/637/1/012086. Ben Massoud, M., Kharbech, O., Mahjoubi, Y., Chaoui, A., & Wingler, A. (2022). Effect of exogenous treatment with nitric oxide (NO) on redox homeostasis in barley seedlings ( Hordeum vulgare L.) under copper stress. J. Soil Sci. Plant Nut. 1-14. https://doi.org/10.1007/s42729-021-00757-w. Zulfiqar, U., Jiang, W., Xiukang, W., Hussain, S., Ahmad, M., Maqsood , M. F., ... & Mustafa, A. (2022). Cadmium phytotoxicity, tolerance, and advanced remediation approaches in agricultural soils; a comprehensive review. Front. Plant Sci . 13, 773815. https://doi.org/10.3389/fpls.2022.773815. Saleem, M. H., Fahad, S., Rehman, M., Saud, S., Jamal, Y., Khan, S., & Liu, L. (2020). Morpho-physiological traits, biochemical response and phytoextraction potential of short-term copper stress on kenaf ( Hibiscus cannabinus L.) seedlings. PeerJ, 8. 8321.http://doi.org/10.7717/peerj.8321. Chen, Y. E., Cui, J. M., Li, G. X., Yuan, M., Zhang, Z. W., Yuan, S., & Zhang, H. Y. (2016). Effect of salicylic acid on the antioxidant system and photosystem II in wheat seedlings. Biol. Plant . 60(1), 139-147. http://doi.org/10.1007/s10535-015-0564-4. Zhang, X., Liu, Y., Zhang, W., Yang, W., An, S., Guo, M., & Chen, G. (2024). Salicylic acid treatment ameliorates postharvest quality deterioration in ‘France’Prune ( Prunus domestica L.‘Ximei’) fruit by modulating the antioxidant system. Foods . 13(18), 2871.http://doi.org/10.3390/foods13182871. Siddiqui, M. H., Alamri, S. A., Al-Khaishany, M. Y., Al-Qutami, M. A., Ali, H. M., & Nasir Khan, M. (2017). Sodium nitroprusside and indole acetic acid improve the tolerance of tomato plants to heat stress by protecting against DNA damage. J. Plant Interact . 12 , 177–186. http://doi.org/10.1080/17429145.2017.1310941. Hasanuzzaman, M., Oku, H., Nahar, K., Bhuyan, M. H. M. B., Mahmud, J. A., & Baluska, F. (2018). Nitric oxide-induced salt stress tolerance in plants: ROS metabolism, signaling and molecular interactions. Plant Biotechnol. Rep. 12(2): 77-92. https://doi.org/10.1007/s11816-018-0480-0. Mostofa, M. G.,Rahman , M. M., Ansary, M. M. U., Fujita, M., & Tran, L. S. P. (2019). Interactive effects of salicylic acid and nitric oxide in enhancing rice tolerance to cadmium stress. Int. J Mol. Sci . 20(22), 5798. http://doi.org/10.3390/ijms20225798. Ibrahim, M. H., Chee Kong, Y., & Mohd Zain, N. A. (2017). Effect of cadmium and copper exposure on growth, secondary metabolites and antioxidant activity in the medicinal plant Sambung Nyawa ( Gynura procumbens (Lour.) Merr). Molecules. 22(10), 1623. http://doi.org/10.3390/molecules22101623. Mostofa, M. G., Seraj, Z. I., & Fujita, M. (2014). Exogenous sodium nitroprusside and glutathione alleviate copper toxicity by reducing copper uptake and oxidative damage in rice ( Oryza sativa L.) seedlings. Protoplasma . 251, 1373–1386. https://doi.org/10.1007/s00709-014-0639-7. Bai, X.Y., Dong, Y.J., Xu, L.L., Kong, J. & Liu, S. (2015). Effects of exogenous nitric oxide on physiological characteristics of perennial ryegrass under cadmium and copper stress. Russ. J. Plant Physiol . 62(2): 237-245. http://doi.org/10.1134/S1021443715020028. Xu, J., Wang, W., Yin, H., Liu, X., Sun, H., & Mi, Q. (2010). Exogenous nitric oxide improves antioxidative capacity and reduces auxin degradation in roots of Medicago truncatula seedlings under cadmium stress. Plant Soil. 326, 321-330. http://doi.org/10.1007/s11104-009-0011-4. Moazam Babasheikhali, M., Jabbarzadeh, Z., Amiri, J., & Barin, M. (2020). Impact of salicylic acid and nitric oxide on improving growth and nutrients uptake of rose in alkaline soil conditions . J. Plant Nutr. 43(5), 667-681. http://doi.org/10.1080/01904167.2019.1701023. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6651901","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":487852760,"identity":"7c2c9ec0-5ca5-429d-889d-130e0f178a7a","order_by":0,"name":"Sorur Arefi","email":"","orcid":"","institution":"Urmia University","correspondingAuthor":false,"prefix":"","firstName":"Sorur","middleName":"","lastName":"Arefi","suffix":""},{"id":487852762,"identity":"52c17022-6a7d-4fae-bc63-0037015a13a2","order_by":1,"name":"Jalil Khara","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0UlEQVRIiWNgGAWjYBACxgY2NhAtByIOgIWYidRiTLwWBgaIlsQGoh3G3MCW9uDnHrv0DbdPJx74wWAnz8DO+4CQw44b9jxLzt1wLnfDwR6GZMMGZnYDAlrY2yR4DjDnbjjDu+EADwNzAgMzG36HgbRI/jlQn24A1HLwD0M9MVrYjknzHDicANJymIfhMBFamtnSpGUOHDecCdIiY3DcsI2QFsP2NjPJNweq5fnO8G7++KaiWp6f/xgBLc0oXGBYEbCDgUGekIJRMApGwSgYBQwA19I9pOtnmhsAAAAASUVORK5CYII=","orcid":"","institution":"Urmia University","correspondingAuthor":true,"prefix":"","firstName":"Jalil","middleName":"","lastName":"Khara","suffix":""}],"badges":[],"createdAt":"2025-05-13 06:08:31","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6651901/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6651901/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-17608-8","type":"published","date":"2025-09-01T15:57:16+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":87229483,"identity":"adc71600-d0c6-455b-a7d4-6af79617d1c2","added_by":"auto","created_at":"2025-07-21 18:11:45","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":529402,"visible":true,"origin":"","legend":"\u003cp\u003eOkra plants under foliar application of salicylic acid and sodium nitroprusside in hydroponic \u0026nbsp;conditions under copper stress after 35days.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6651901/v1/e9d302ce8c730f2a57823053.png"},{"id":90828003,"identity":"45756161-7424-4c4a-9205-4b5b210dbe4c","added_by":"auto","created_at":"2025-09-08 16:04:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2312422,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6651901/v1/ffe6b089-15f8-4964-b50a-7923f9ff21d3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eProtective Role of Salicylic Acid and Sodium Nitroprusside Foliar Application Against Copper Stress in Okra (\u003cem\u003eAbelmoschus esculentus\u003c/em\u003e)\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eOkra (\u003cem\u003eAbelmoschus esculentus\u003c/em\u003e) is an annual crop belonging to the Malvaceae family (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). This species demonstrates high adaptability to a wide range of soil types and is classified as a warm-season vegetable. It thrives best in tropical and subtropical climates, although it is sensitive to cold nighttime temperatures and drought conditions. The natural distribution of okra has been documented in the Middle East and surrounding regions (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Heavy metal (HMs) contamination presents significant environmental and ecological challenges worldwide (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). The primary issue with HMs arises from their non-biodegradable nature, which, unlike organic contaminants, causes them to persist in the environment. This characteristic renders HMs among the most hazardous groups of environmental pollutants (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). The toxicity of metals to plants is typically linked to their availability in soils and their chemical form within the soil matrix (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). The widespread use of copper-based compounds, such as fertilizers, pesticides, and nematicides, has led to extensive copper contamination of agricultural soils (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). While copper is a vital micronutrient for plants, its excess accumulation may disrupt photosynthetic and respiratory processes, enzymatic functions, and cellular membrane integrity, leading to membrane damage, reduced metabolism, and, ultimately, cell death (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). The most prominent impact of copper toxicity is the induction of oxidative stress by stimulating the production of harmful reactive oxygen species (ROS), such as superoxide and hydrogen peroxide. Due to their high reactivity with cellular components, these free radicals cause damage to cells and DNA while inhibiting ATP production. The presence of toxic levels of HMs in the plant environment induces physiological changes that reduce growth potential and, in severe cases, lead to plant mortality. Sensitive plants suffer damage and perish under these conditions, while resistant plants continue to grow and reproduce (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). The generation of ROS, induced by oxidative stress from high copper concentrations, can lead to lipid peroxidation of cell membranes. Additionally, plants undergo alterations in their metabolic pathways, affecting the synthesis of essential biomolecules such as proteins and lipids (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). HMs-induced stress can interfere with the uptake of essential elements like calcium (Ca), phosphorus (P), magnesium (Mg), and other metals, disrupting the elemental balance in plants (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). In response to HMs stress, plants activate antioxidant defense systems, including enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), to mitigate the excessive accumulation of free radicals (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Other defense mechanisms plants employ under HMs stress include the accumulation of proline (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e), increased carbohydrate storage (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e), and enhanced protein synthesis (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Proline helps protect plants against stress through mechanisms like membrane stabilization, osmotic regulation, and the preservation of enzyme structure and function (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Studies by Rather et al. (2020) (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e) demonstrate that the using plant growth regulators, hormones, and other signaling molecules is a key strategy for alleviating copper toxicity in plants. Salicylic acid (SA), a plant growth regulator, is crucial in modulating various stages of plant growth and development, including ion uptake, photosynthesis, germination, enzymatic activity, and nitrogen regulation (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e). As a naturally occurring phenolic compound, SA effectively mitigates the adverse effects of environmental abiotic stresses (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Numerous studies have shown that SA application alleviates the negative impacts of drought stress (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e), cold stress (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), salinity stress (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e), and HMs stress (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). Research by Wei et al. (2020)(\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e) has conclusively demonstrated that SA significantly reduces the toxic effects of HMs stress and, in interaction with nitric oxide, ameliorates the detrimental impacts of HMs toxicity on plants.\u003c/p\u003e\u003cp\u003eNitric oxide (NO) is a vital signaling molecule involved in numerous biochemical and physiological processes in plants, which has led to its classification as a phytohormone. NO acts as a concentration-dependent regulator, participating in key processes such as hypocotyl growth, defense responses, stomatal movement, seed germination, programmed cell death, hypersensitive responses, photosynthesis, growth and development, and phytoalexin production under various stress conditions (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Sodium nitroprusside (SNP), an NO donor, is a bioactive molecule that can be applied through irrigation, foliar spraying, or injection into the apoplast of the leaf (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e). It has been reported that SNP effectively mitigates the adverse effects of abiotic stresses, including HMs stress. In recent studies, SNP has been used as a source of NO due to its unique ability to release nitric oxide in plant tissues over an extended period, as well as its cost-effectiveness (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). Although limited research has been conducted on the effects of foliar application of SNP and SA on enhancing okra plant tolerance to copper sulfate stress, this study investigates their individual and combined effects under copper toxicity. The study primarily focuses on the physiological and biochemical changes in okra plants, alongside their mineral element content, under copper toxicity. The primary aim of this research is to evaluate the enhancement of plant tolerance by stimulating related mechanisms, such as antioxidant activity, while also reducing copper accumulation and limiting its translocation from roots to shoots through the use of SNP and SA.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThe plant studied in this research was okra, with seeds of the Clemson Spineless cultivar obtained from the Dutch company Bakker Brothers. Initially, the seeds were disinfected in a 5% sodium hypochlorite solution for 10 minutes, then rinsed several times with tap water and once with distilled water. Four seeds were sown in plastic pots (20 \u0026times; 30 cm\u0026sup2;) filled with perlite, with three independent replicates per treatment, arranged in a completely randomized design. Until the emergence of the first sprout, the pots were irrigated with distilled water and kept in darkness. Upon observing the initial signs of germination, the pots were transferred to a growth chamber with a minimum temperature of 25\u0026deg;C and a maximum of 30\u0026deg;C, 80% relative humidity, and a photoperiod of 14 hours of light and 10 hours of darkness. At the four-leaf stage, the plants were irrigated with Hoagland nutrient solution (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e) at 1/4 and 1/2 strength (each concentration applied for one week), followed by full-strength Hoagland solution alternated with distilled water every other day. At the 6\u0026ndash;8 leaf stage, the plants were subjected to foliar application of SNP at 150 \u0026micro;M and SA at 500 \u0026micro;M, each applied separately and also in combination, with treatments repeated twice at a one-week interval. Twenty-four hours after the foliar treatments, the plants were exposed to copper sulfate (CuSO₄) stress at concentrations of 600 and 1200 \u0026micro;M for 14 days. After 35 days (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e, both shoot and root samples were collected for analysis. Fresh samples were immediately separated and stored at -80\u0026deg;C. The fresh weight of shoots and roots was measured using a digital scale with a precision of 0.001 g. The dry weight of shoots and roots was determined by oven-drying the samples at 75\u0026deg;C for 24 hours. Plant height was measured using a ruler.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eDetermination of malondialdehyde content and hydrogen peroxide levels\u003c/h2\u003e\u003cp\u003eTo determine the MDA content, 0.2 g of fresh shoot or root tissue was thoroughly homogenized in 5 mL of 0.1% (w/v) trichloroacetic acid (TCA). The homogenate was centrifuged (5 min, 10,000 g), and the supernatant was collected. An equal volume of TCA containing 0.5% (w/v) thiobarbituric acid (TBA) was added to the supernatant. The reaction mixture was incubated in a water bath at 95\u0026deg;C for 30 min and then rapidly cooled in an ice bath. After cooling, the samples were centrifuged again (10 min, 10,000 g), and the absorbance of the clear supernatant was recorded at 532 and 600 nm using a spectrophotometer. Finally, the MDA concentration was calculated and expressed as (\u0026micro;mol g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e FW) (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e). Additionally, H₂O₂ levels were measured by homogenizing 0.5 g of shoot and root tissues in 0.1% TCA. The resulting homogenate was mixed with potassium phosphate buffer and potassium iodide to form the reaction mixture. Absorbance was then recorded at 390 nm (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eDetermination of Cell Death\u003c/h3\u003e\n\u003cp\u003eTo assess cell death, three 1-cm segments from the root tips of copper sulfate-treated plants and control samples were immersed in a 0.025% Evans blue solution for 30 minutes to specifically stain non-viable cells. Excess dye was removed by thoroughly washing the samples with distilled water for 15 minutes. To extract the dye bound to dead cells, the samples were homogenized in 1 mL of 50% methanol and incubated in a water bath at 50\u0026deg;C for 15 minutes. After centrifugation at 14,000g, the percentage of cell death was determined by measuring the absorbance of the supernatant at a wavelength of 600 nm and comparing it to the untreated control sample (\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eDetermination of Soluble Sugar, Proline and Total Soluble Protein Content\u003c/h3\u003e\n\u003cp\u003eIn this study, soluble sugar content was quantified in 0.5 g samples of root and shoot tissues using the phenol-sulfuric acid method (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). Proline content was determined according to a previously established protocol with slight modifications (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e). For this, 0.2 g of leaf or root tissue was homogenized in 3 mL of 3% sulfosalicylic acid. The homogenate was then mixed with ninhydrin reagent and glacial acetic acid, followed by incubation at 100\u0026deg;C for 1 hour. The reaction mixture was rapidly cooled in an ice bath, after which 4 mL of toluene was added. The absorbance of the upper organic phase was measured at 520 nm using a spectrophotometer. Total soluble protein content was measured using the Bradford method (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e), and the resulting protein extract was subsequently used for the determination of antioxidant enzymes activities.\u003c/p\u003e\n\u003ch3\u003eDetermination of Antioxidant Enzymes Activities\u003c/h3\u003e\n\u003cp\u003eThe activities of catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7), and superoxide dismutase (SOD, EC 1.15.1.1) were determined following the method described by Chance and Maehly (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e). CAT activity was assessed by measuring the decrease in absorbance at 240 nm due to the decomposition of H₂O₂, while POD activity was determined by monitoring the oxidation of guaiacol at 470 nm. SOD activity was evaluated based on its ability to inhibit the photoreduction of nitroblue tetrazolium (NBT) at 560 nm (\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e). Enzyme activities were expressed as units per milligram of protein per minute.\u003c/p\u003e\n\u003ch3\u003eDetermination of Elemental Content\u003c/h3\u003e\n\u003cp\u003eThe total elemental content was assessed using a modified Sagner et al. (1998) (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e) method. Plant root and shoot samples were dried at 70\u0026deg;C for 72 hours, and 0.5 g of each was digested in 10 mL of 65% (w/v) ultrapure nitric acid (Merck). After digestion, the volume was adjusted to 50 mL with deionized water, and concentrations of Cu, Fe, Mg and Zn were measured via atomic absorption spectrophotometry (AA6200 Shimadzu). To assess the translocation of Cu from roots to shoots, the translocation factor (TF) was calculated based on the following Eq.\u0026nbsp;(44).\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:TF=\\frac{Cu\\:concentration\\:in\\:the\\:shoots}{Cu\\:concentration\\:in\\:the\\:roots}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eThe results of plant growth indices (fresh weight, dry weight, shoot length, and root length)\u003c/h2\u003e\u003cp\u003eCopper stress significantly reduced the fresh and dry weights of shoots and roots, as well as their lengths, compared to the control, with the most pronounced effects at 1200 \u0026micro;M. Cu stress also led to a significant reduction in shoot and root lengths, highlighting its inhibitory effect on plant growth. At 1200 and 600 \u0026micro;M Cu, shoot fresh weight decreased by 2.41- and 3.77-fold, root fresh weight by 2.16- and 3.84-fold, shoot dry weight by 2.22- and 7.06-fold, and root dry weight by 2.46- and 6.55-fold, respectively. However, applying SA and SNP, alone or combined with Cu, significantly enhanced growth indices under stress. The application of SA and SNP alleviated Cu-induced growth inhibition and improved shoot and root development. The greatest improvements in shoot fresh and dry weights were observed in Cu1200\u0026thinsp;+\u0026thinsp;SA (31.63%) and Cu1200\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP (50.03%), respectively, while root fresh and dry weights peaked in Cu600\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP (36.92%) and Cu1200\u0026thinsp;+\u0026thinsp;SA (63.46%), respectively, compared to Cu-stressed plants without SA or SNP (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInteractive Effects of Copper Stress, SA, and SNP on Growth Parameters in Okra\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatments\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRoot fresh weight/plant\u003c/p\u003e\u003cp\u003e(g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRoot dry weight/plant\u003c/p\u003e\u003cp\u003e(g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eRoot length\u003c/p\u003e\u003cp\u003e(cm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eShoot length\u003c/p\u003e\u003cp\u003e(cm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eShoot fresh weight/plant\u003c/p\u003e\u003cp\u003e(g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eShoot dry weight/plant\u003c/p\u003e\u003cp\u003e(g)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.020a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e28.2 3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.16\u0026thinsp;\u0026plusmn;\u0026thinsp;1.16 ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e13.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.55c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e2.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e500 \u0026micro;M SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.81\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0 4a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e26.43\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40. 83\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0 ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.49ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e2.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0 8a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e150 \u0026micro;M SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.024a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e25.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e39.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.69b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e15.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87 abc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e29.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e42.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.55 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25 a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35 cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e25.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31 e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e9.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87 de\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1..32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e +SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.023b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e22.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e28.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.61 d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e14.23\u0026thinsp;\u0026plusmn;\u0026thinsp;1.07bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 bc\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.46 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.43\u0026thinsp;\u0026plusmn;\u0026thinsp;0.023c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e25.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e29.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62 d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19bc\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24 c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.43\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.028c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e26.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e32.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e13.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.92\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.03b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20 e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.12\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.030e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e14.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e16.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.73h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e3.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30 f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.416\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.04d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.012d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e18.5\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.76 f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e23.96\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.54ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e8.18\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.46e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.649\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.020e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28 f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e20.6 3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.63 g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.69\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64 f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.569\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.34\u0026thinsp;\u0026plusmn;\u0026thinsp;0.024d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e22.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e23..13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59 f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.044\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThree different letters indicate a significant difference at the 5% level based on Duncan's test.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eResults of Malondialdehyde Content, Hydrogen Peroxide Levels, and Cell Death\u003c/h3\u003e\n\u003cp\u003eThis study revealed that Cu stress significantly increased H₂O₂ levels and MDA content in shoots and roots, peaking in the 1200 \u0026micro;M Cu treatment and lowest in the control. However, applying SA and SNP, alone or combined, significantly lowered these parameters in stressed plants. The greatest H₂O₂ reduction occurred in the Cu600\u0026thinsp;+\u0026thinsp;SA treatment (26.93% in shoots), Cu600\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP (18.79% in roots), while MDA decreased most in Cu600\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP for shoots (15.42%) and Cu600\u0026thinsp;+\u0026thinsp;SA for roots (14.99%) compared to Cu-only treatments. Under non-stress conditions, SA, SNP, or their combination showed no significant impact on H₂O₂ or MDA levels \u003cb\u003e(\u003c/b\u003eTables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e Increasing Cu in the nutrient solution elevated root cell death, but SA and SNP, applied individually or in combination, mitigated this effect. The highest cell death was observed in the 1200 \u0026micro;M Cu treatment, while SA and SNP proved effective across various Cu concentrations. The combination of SA and SNP in the CuSO\u003csub\u003e4\u003c/sub\u003e (600 \u0026micro;M)\u0026thinsp;+\u0026thinsp;SA treatment resulted in the reduction (45%). Under non-stress conditions, these compounds had no effect \u003cb\u003e(\u003c/b\u003eTables\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e\n\u003ch3\u003eResults of Soluble Sugar, Proline and Protein Content\u003c/h3\u003e\n\u003cp\u003eThe analysis of copper stress effects on okra showed a significant increase in soluble carbohydrate content in both shoot and root tissues compared to the control, with the highest increase observed in the 1200 \u0026micro;M copper treatment. The use of SA, SNP, and their combination under both copper stress levels resulted in a significant reduction in carbohydrate content. The greatest reduction was observed in the CuSO₄ (600 \u0026micro;M)\u0026thinsp;+\u0026thinsp;SA treatment, with decreases of 10.04% in the shoots and 9.70% in the roots compared to copper treatments alone. When SNP was co-applied with copper, carbohydrate content decreased further, with reductions of 4.77% and 5.94% in the shoots and 7.08% and 6.15% in the roots under Cu 600\u0026thinsp;+\u0026thinsp;SNP and Cu 1200\u0026thinsp;+\u0026thinsp;SNP treatments, respectively. Under non-stress conditions, SA and SNP treatments had no effect on soluble carbohydrate content in the shoots. However, in the roots, SNP treatment significantly increased carbohydrate content in the 600 \u0026micro;M treatment \u003cb\u003e(\u003c/b\u003eTables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e\u003cp\u003eOur research findings demonstrated that copper stress led to an increase in proline content in both the shoots and roots of the plant. The highest proline accumulation was observed in the shoots of the 1200 \u0026micro;M Cu treatment, showing a sixfold increase compared to the control. The application of SA reduced proline content in okra plants under copper stress. However, SNP treatment, in combination with 600 and 1200 \u0026micro;M Cu stress, significantly increased proline content in the shoots by 81.96% and 85.51%, respectively, and in the roots by 37.53% and 47.31% compared to the control group. Under non-stress conditions, SNP application did not affect proline content \u003cb\u003e(\u003c/b\u003eTables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe results of the (Cu) effect assessment revealed that protein content significantly increased in shoots by 34.82% and 59.95% at 600 and 1200 \u0026micro;M Cu treatments, respectively, and by 47.47% in roots at 1200 \u0026micro;M Cu, while no significant change was observed in roots at 600 \u0026micro;M Cu. The application of (SA) and (SNP), individually or in combination, further increased protein content in shoots and roots under Cu stress. The greatest increases were recorded in the Cu1200\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP treatment for shoots (63.65%) and in the Cu1200\u0026thinsp;+\u0026thinsp;SNP treatment for roots (57.63%). Under non-stress conditions, protein content in treated plants also rose compared to the control \u003cb\u003e(\u003c/b\u003eTables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInteractive Effects of Copper Stress, SA, and SNP on MDA Content, H₂O₂ Levels, and Proline, Sugar, and Protein Content in Shoot\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatments\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMDAShoot\u003c/p\u003e\u003cp\u003e(\u0026micro;mol/g FW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\u003cp\u003eShoot\u003c/p\u003e\u003cp\u003e(\u0026micro;mol/g FW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSoluble Sugar\u003c/p\u003e\u003cp\u003eShoot\u003c/p\u003e\u003cp\u003e(mg/g FW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eProline\u003c/p\u003e\u003cp\u003eShoot\u003c/p\u003e\u003cp\u003e(nmol/g FW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTotal Proteins\u003c/p\u003e\u003cp\u003eShoot\u003c/p\u003e\u003cp\u003e(mg/g FW)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.445\u0026thinsp;\u0026plusmn;\u0026thinsp;0.022e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.03e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e32.05\u0026thinsp;\u0026plusmn;\u0026thinsp;1.05f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.903\u0026thinsp;\u0026plusmn;\u0026thinsp;0.071d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e7.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.415f\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e500 \u0026micro;M SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.454\u0026thinsp;\u0026plusmn;\u0026thinsp;0.019e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04 e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e32.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.151d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e9.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.231e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e150 \u0026micro;M SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0467\u0026thinsp;\u0026plusmn;\u0026thinsp;0.020e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07 e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e34.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.053\u0026thinsp;\u0026plusmn;\u0026thinsp;0.103d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e9.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0389e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.454\u0026thinsp;\u0026plusmn;\u0026thinsp;0.012e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07 e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e32.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.416f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.069d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e9.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.410e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.662\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0402c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.013c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e40.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.458c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.081b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.289d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e +SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.595\u0026thinsp;\u0026plusmn;\u0026thinsp;0.024 cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.07\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e36.91\u0026thinsp;\u0026plusmn;\u0026thinsp;0.471d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.07\u0026thinsp;\u0026plusmn;\u0026thinsp;0.133c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e13.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.170 c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.616\u0026thinsp;\u0026plusmn;\u0026thinsp;0.035 cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.92\u0026thinsp;\u0026plusmn;\u0026thinsp;0.09d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e38.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.54d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.156b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e12.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.612c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.573 1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.028d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11 d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e38.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.428d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.223b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e13.49\u0026thinsp;\u0026plusmn;\u0026thinsp;1.075c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.949\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0201a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e49.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.858a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.138a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e18.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.252 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.848\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0287b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e45.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.103b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.248b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e18.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.470 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.858\u0026thinsp;\u0026plusmn;\u0026thinsp;0.204b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e47.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.585b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.107a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e18.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.967 b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.848\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0315b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14 bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e46.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.409b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.285a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e19.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.537a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThree different letters indicate a significant difference at the 5% level based on Duncan's test.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInteractive Effects of Copper Stress, SA, and SNP on MDA, H₂O₂, Proline, Sugar, Protein Content, and Cell Death Percentage in Roots\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatments\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMDA\u003c/p\u003e\u003cp\u003eRoot\u003c/p\u003e\u003cp\u003e(\u0026micro;mol/g FW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\u003cp\u003eRoot\u003c/p\u003e\u003cp\u003e(\u0026micro;mol/g FW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCell death\u003c/p\u003e\u003cp\u003eRoot\u003c/p\u003e\u003cp\u003e(% of control)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eSoluble sugar\u003c/p\u003e\u003cp\u003eRoot\u003c/p\u003e\u003cp\u003e(mg/g FW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eProline\u003c/p\u003e\u003cp\u003eRoot\u003c/p\u003e\u003cp\u003e(nmol/g FW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTotal Proteins\u003c/p\u003e\u003cp\u003eRoot\u003c/p\u003e\u003cp\u003e(mg/g FW)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.209\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0012 e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.087\u0026thinsp;\u0026plusmn;\u0026thinsp;0.030d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e91.35\u0026thinsp;\u0026plusmn;\u0026thinsp;7.42g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e23.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.408 gh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.265f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e2.97\u0026thinsp;\u0026plusmn;\u0026thinsp;0.433f\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e500 \u0026micro;M SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.198\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0013e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.072\u0026thinsp;\u0026plusmn;\u0026thinsp;0.073d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e109.50\u0026thinsp;\u0026plusmn;\u0026thinsp;8.79g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e22.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.577g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.099 def\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e4.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.217d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e150 \u0026micro;M SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.201\u0026thinsp;\u0026plusmn;\u0026thinsp;0.009e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.087\u0026thinsp;\u0026plusmn;\u0026thinsp;0.004d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e134.73\u0026thinsp;\u0026plusmn;\u0026thinsp;3.93g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e22.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.360h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.315de\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3.37\u0026thinsp;\u0026plusmn;\u0026thinsp;0.301ef\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.195\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0009e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.085\u0026thinsp;\u0026plusmn;\u0026thinsp;0.008d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e96.56\u0026thinsp;\u0026plusmn;\u0026thinsp;16.21 g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e24.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.451gh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.188ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e4.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.304de\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.2 95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.014c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.138\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e398.52\u0026thinsp;\u0026plusmn;\u0026thinsp;10.10c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e28.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.927cde\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e6.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.223c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.422ef\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e +SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.251\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0121d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.121\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e212.23\u0026thinsp;\u0026plusmn;\u0026thinsp;20.20f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e25.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.508fg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.291\u0026thinsp;\u0026plusmn;\u0026thinsp;0.118d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.238ef\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.265\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0128 cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.123\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e319.40\u0026thinsp;\u0026plusmn;\u0026thinsp;24.59de\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e26.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.608ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e7.346\u0026thinsp;\u0026plusmn;\u0026thinsp;0.192b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e4.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.158de\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.281\u0026thinsp;\u0026plusmn;\u0026thinsp;0.009cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.112\u0026thinsp;\u0026plusmn;\u0026thinsp;0.006c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e274.26\u0026thinsp;\u0026plusmn;\u0026thinsp;21.09ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e27.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.459def\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.248d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e4.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.307d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.414\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0138a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.163\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e736.07\u0026thinsp;\u0026plusmn;\u0026thinsp;48.90a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e32.76\u0026thinsp;\u0026plusmn;\u0026thinsp;1.240a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e8.212\u0026thinsp;\u0026plusmn;\u0026thinsp;0.164a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e5.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.423c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.356\u0026thinsp;\u0026plusmn;\u0026thinsp;0.008b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.144\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e372.57\u0026thinsp;\u0026plusmn;\u0026thinsp;30.71cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e28.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.266bcd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e7.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.280b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.207b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.379\u0026thinsp;\u0026plusmn;\u0026thinsp;0005b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.148\u0026thinsp;\u0026plusmn;\u0026thinsp;0.005b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e537.13\u0026thinsp;\u0026plusmn;\u0026thinsp;23.28b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e30.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.526b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e8.564\u0026thinsp;\u0026plusmn;\u0026thinsp;0.262a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e7.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.408a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.378\u0026thinsp;\u0026plusmn;\u0026thinsp;0.011 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.144\u0026thinsp;\u0026plusmn;\u0026thinsp;0.004b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e400.84\u0026thinsp;\u0026plusmn;\u0026thinsp;21.09c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e29.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.440bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e7.984\u0026thinsp;\u0026plusmn;\u0026thinsp;0.248ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.239ab\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThree different letters indicate a significant difference at the 5% level based on Duncan's test.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eResults of Antioxidant Enzymes Activity\u003c/h2\u003e\u003cp\u003eAccording to the results obtained from Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, SOD enzyme activity increased by 35.55% and 53.59% in the shoots and by 73.93% and 89.52% in the roots under 600 and 1200 \u0026micro;M Cu treatments, respectively, compared to the control. Foliar spraying of SA and SNP, either individually or in combination, further enhanced SOD activity under Cu stress. The highest SOD activity was observed in the Cu1200\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP treatment, with increases of 67.11% in shoots and 92.17% in roots compared to the control. With increasing Cu concentrations, POD enzyme activity rose by 59.18% and 84.17% in shoots and by 73.44% and 84.79% in roots. Application of SA and SNP, either separately or together, significantly enhanced POD activity in Cu-treated plants compared to the control. The greatest increases were recorded in the Cu1200\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP treatment for shoots 88.40% and in the Cu1200\u0026thinsp;+\u0026thinsp;SA treatment for roots 86.80%. In non-stress conditions, foliar application of SA and SNP had no significant effect on POD activity in shoots; however, in roots, the combined SA\u0026thinsp;+\u0026thinsp;SNP treatment resulted in an increased POD activity. The results for CAT enzyme activity indicated increases at both Cu levels, with rises of 29.68% and 57.94% in shoots and 19.54% and 27.61% in roots compared to the control. In plants subjected to foliar application of SA and SNP (either individually or in combination), CAT activity was higher compared to plants exposed to Cu stress alone. The highest increases in CAT activity were observed in the Cu1200\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP treatment, with enhancements of 67.04% in shoots and 67.02% in roots relative to the control \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInteractive Effects of Copper Stress, SA, and SNP on Antioxidant Enzyme Activity in Shoots and Roots\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatments\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSOD Shoot\u003c/p\u003e\u003cp\u003eunit mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e protein\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCAT Shoot\u003c/p\u003e\u003cp\u003eunit mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003eprotein\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePOD Shoot\u003c/p\u003e\u003cp\u003eunit mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003eprotein\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eSOD Root\u003c/p\u003e\u003cp\u003eunitmg\u003csup\u003e1\u003c/sup\u003eprotein\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eCAT Root\u003c/p\u003e\u003cp\u003eunit mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003eprotein\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003ePOD Root\u003c/p\u003e\u003cp\u003eunit mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e protein\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12.63\u0026thinsp;\u0026plusmn;\u0026thinsp;1.33e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e18.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.533i\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.789\u0026thinsp;\u0026plusmn;\u0026thinsp;0.058g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.417g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.572h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.073f\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e500 \u0026micro;M SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.481f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.440 h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.997\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0827g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.736 g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e12.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.449gh\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.231ef\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e150 \u0026micro;M SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10.83\u0026thinsp;\u0026plusmn;\u0026thinsp;1.03f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.768 h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.799\u0026thinsp;\u0026plusmn;\u0026thinsp;0.085 fg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.92\u0026thinsp;\u0026plusmn;\u0026thinsp;0.499g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e14.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.811fg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.305f\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.576 e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21.44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.446h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.136f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e5.66\u0026thinsp;\u0026plusmn;\u0026thinsp;1.94g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e15.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.751f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.408e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e19.61\u0026thinsp;\u0026plusmn;\u0026thinsp;1.92d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.881g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.211e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e19.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.66f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e19.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.443e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e5.561\u0026thinsp;\u0026plusmn;\u0026thinsp;0.149d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e22.78\u0026thinsp;\u0026plusmn;\u0026thinsp;1.37d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e28.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.548f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.292d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e29.75\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e22.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.09d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6.708\u0026thinsp;\u0026plusmn;\u0026thinsp;0.733c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e26.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.885c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e30.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.580ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.219d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e28.29\u0026thinsp;\u0026plusmn;\u0026thinsp;2.60e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e24.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.846d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.414c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e29.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.735bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e32.01\u0026thinsp;\u0026plusmn;\u0026thinsp;1.01ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.374d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e37.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.55d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e24.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.554d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e7.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.210c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e27.23\u0026thinsp;\u0026plusmn;\u0026thinsp;1.51c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e42.84\u0026thinsp;\u0026plusmn;\u0026thinsp;1.31d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.313c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e51.17\u0026thinsp;\u0026plusmn;\u0026thinsp;3.39c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e27.61\u0026thinsp;\u0026plusmn;\u0026thinsp;1.05c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e9.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.182b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e32.18\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e45.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.843c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.351ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e59.29\u0026thinsp;\u0026plusmn;\u0026thinsp;.2.29b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e32.96\u0026thinsp;\u0026plusmn;\u0026thinsp;.1.03b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e11.197\u0026thinsp;\u0026plusmn;\u0026thinsp;0.678a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e36.21\u0026thinsp;\u0026plusmn;\u0026thinsp;1.62a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e51.15\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.239b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e60.58\u0026thinsp;\u0026plusmn;\u0026thinsp;2.26b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e33.78\u0026thinsp;\u0026plusmn;\u0026thinsp;0.874ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e10.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.232ab\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e38.43\u0026thinsp;\u0026plusmn;\u0026thinsp;1.71a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e54.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.187a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e68.48\u0026thinsp;\u0026plusmn;\u0026thinsp;2.20a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e35.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.572a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e11.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.400a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThree different letters indicate a significant difference at the 5% level based on Duncan's test.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eResults of Elemental Levels (Cu, Zn, Mg, and Fe) and TF\u003c/h2\u003e\u003cp\u003eThe results showed that Cu stress reduced Zn, Mg, and Fe contents in the shoots and roots of okra plants at 600 and 1200 \u0026micro;M Cu levels. However, applying SA and SNP significantly elevated these elements in specific treatments. The largest increases were recorded for Zn in the Cu600\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP treatment (50.40%) and Mg in the Cu600\u0026thinsp;+\u0026thinsp;SA treatment (41.78%). Likewise, Fe content increased in the Cu600\u0026thinsp;+\u0026thinsp;SA (38.37%) and Cu600\u0026thinsp;+\u0026thinsp;SNP (51.38%) treatments. In contrast, Cu content in plants under 1200 \u0026micro;M Cu stress rose substantially compared to the control, yet SA and SNP application significantly lowered Cu levels in shoots (58.46%) and roots (73.42%) in the Cu600\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP treatment. Data of Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e indicated that the translocation factor (TF) decreased with higher Cu concentrations, due to Cu-induced stress and reduced plant ability to transfer Cu from roots to shoots. These results suggest that okra is not a hyperaccumulator under Cu stress, as its TF remained below 1 \u003cb\u003e(\u003c/b\u003eTables\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003e\u003cb\u003eInteractive Effects of Copper Stress, SA, and SNP on Elemental Content in Okra Shoots\u003c/b\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatments\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMg Shoot\u003c/p\u003e\u003cp\u003e(mg/g DW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eFe Shoot\u003c/p\u003e\u003cp\u003e(mg/g DW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCu Shoot\u003c/p\u003e\u003cp\u003e(\u0026micro;g/g DW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eZn Shoot\u003c/p\u003e\u003cp\u003e(mg/g DW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTF\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.065b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.151\u0026thinsp;\u0026plusmn;\u0026thinsp;0.005a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e36\u0026thinsp;\u0026plusmn;\u0026thinsp;1.616g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.028\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0003a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.393\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e500 \u0026micro;M SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.140a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.152\u0026thinsp;\u0026plusmn;\u0026thinsp;0.006 a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e35.73\u0026thinsp;\u0026plusmn;\u0026thinsp;2.082g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.029\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0007a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.273\u0026thinsp;\u0026plusmn;\u0026thinsp;0.023b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e150 \u0026micro;M SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.110a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.147\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e36.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.890fg\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.028\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0007a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.276\u0026thinsp;\u0026plusmn;\u0026thinsp;0.027b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.153\u0026thinsp;\u0026plusmn;\u0026thinsp;0.008a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e38.13\u0026thinsp;\u0026plusmn;\u0026thinsp;3.014gf\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.030\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0004a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.273\u0026thinsp;\u0026plusmn;\u0026thinsp;0.039b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.109d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.07\u0026thinsp;\u0026plusmn;\u0026thinsp;0.005 d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e130.6\u0026thinsp;\u0026plusmn;\u0026thinsp;6.150d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.018. \u0026plusmn;0.0004de\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.206\u0026thinsp;\u0026plusmn;\u0026thinsp;0.012 bc\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.072c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.002b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e99.6\u0026thinsp;\u0026plusmn;\u0026thinsp;11.60e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.021\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0004bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.161\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.104c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.007 b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e54.26\u0026thinsp;\u0026plusmn;\u0026thinsp;2.755gf\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.020\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0003bcd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.202\u0026thinsp;\u0026plusmn;\u0026thinsp;0.005 bc\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;MCuSO4\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.096c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.007b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e65.33\u0026thinsp;\u0026plusmn;\u0026thinsp;5.871f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.023\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0008b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.182\u0026thinsp;\u0026plusmn;\u0026thinsp;0.023 bc\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200 \u0026micro;M CuSO4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.69\u0026thinsp;\u0026plusmn;\u0026thinsp;0.065e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.052\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003 e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e265.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.340a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.014\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0004f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.206\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003bc\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO4\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.080d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.108\u0026thinsp;\u0026plusmn;\u0026thinsp;0.006bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e182.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.33c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.019\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.0002cde\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.156\u0026thinsp;\u0026plusmn;\u0026thinsp;0.012c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO4\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.293\u0026thinsp;\u0026plusmn;\u0026thinsp;0.153d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.092\u0026thinsp;\u0026plusmn;\u0026thinsp;0.008cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e224.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.66b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.016\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0003ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.220\u0026thinsp;\u0026plusmn;\u0026thinsp;0.015 bc\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO4\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.382\u0026thinsp;\u0026plusmn;\u0026thinsp;0.167d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.096\u0026thinsp;\u0026plusmn;\u0026thinsp;0.006c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e203.2\u0026thinsp;\u0026plusmn;\u0026thinsp;20.38bc\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.018\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0003cde\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.203\u0026thinsp;\u0026plusmn;\u0026thinsp;0.017bc\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThree different letters indicate a significant difference at the 5% level based on Duncan's test.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eInteractive Effects of Copper Stress, SA, and SNP on Elemental Content in Okra Roots\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTreatments\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMg Root\u003c/p\u003e\u003cp\u003e(mg/g DW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eFe Root\u003c/p\u003e\u003cp\u003e(mg/g DW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCu Root\u003c/p\u003e\u003cp\u003e(\u0026micro;g/g DW)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eZn Root\u003c/p\u003e\u003cp\u003e(mg/g DW)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eControl\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.86\u0026thinsp;\u0026plusmn;\u0026thinsp;0.035b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.059a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e93.73\u0026thinsp;\u0026plusmn;\u0026thinsp;7.62g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.047\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0005a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e500 \u0026micro;M SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.183\u0026thinsp;\u0026plusmn;\u0026thinsp;0.084a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.151\u0026thinsp;\u0026plusmn;\u0026thinsp;0.063a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e130.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.34g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.045 83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.005a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e150 \u0026micro;M SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.109ab\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.034a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e135.7\u0026thinsp;\u0026plusmn;\u0026thinsp;10.55g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.047.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0018a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.087a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.57\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e142.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.873g\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.048.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0012a\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.052de\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.864\u0026thinsp;\u0026plusmn;\u0026thinsp;0.036c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e628.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.75d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.024.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0016cd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600 \u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.34\u0026thinsp;\u0026plusmn;\u0026thinsp;0.116cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.031b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e595\u0026thinsp;\u0026plusmn;\u0026thinsp;66.36 d\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.035\u0026thinsp;\u0026plusmn;\u0026thinsp;0.001b\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;M CuSO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.59\u0026thinsp;\u0026plusmn;\u0026thinsp;0.117c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.07\u0026thinsp;\u0026plusmn;\u0026thinsp;0.059b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e269.8\u0026thinsp;\u0026plusmn;\u0026thinsp;22.28f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.029\u0026thinsp;\u0026plusmn;\u0026thinsp;0.001cd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e600\u0026micro;MCuSO4\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.167cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.074b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e360\u0026thinsp;\u0026plusmn;\u0026thinsp;16.16e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.029\u0026thinsp;\u0026plusmn;\u0026thinsp;0.003c\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200 \u0026micro;M CuSO4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.083f\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.438\u0026thinsp;\u0026plusmn;\u0026thinsp;0.061e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1290.9\u0026thinsp;\u0026plusmn;\u0026thinsp;40.31a\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.017\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0008e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO4\u0026thinsp;+\u0026thinsp;SA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.037e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.695\u0026thinsp;\u0026plusmn;\u0026thinsp;0.074cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1151\u0026thinsp;\u0026plusmn;\u0026thinsp;20.24b\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.026\u0026thinsp;\u0026plusmn;\u0026thinsp;.0.0005cd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO4\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.061e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.596\u0026thinsp;\u0026plusmn;\u0026thinsp;0.073de\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1025\u0026thinsp;\u0026plusmn;\u0026thinsp;47.20c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.027\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0004d\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1200\u0026micro;MCuSO4\u0026thinsp;+\u0026thinsp;SA\u0026thinsp;+\u0026thinsp;SNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.91\u0026thinsp;\u0026plusmn;\u0026thinsp;0.058e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.689\u0026thinsp;\u0026plusmn;\u0026thinsp;0.070cd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e878\u0026thinsp;\u0026plusmn;\u0026thinsp;11.93c\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.026\u0026thinsp;\u0026plusmn;\u0026thinsp;0.001cd\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThree different letters indicate a significant difference at the 5% level based on Duncan's test\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eCopper exposure substantially reduced growth, height, and both the fresh and dry biomass of shoots and roots in okra plants. These detrimental effects arise from the heightened sensitivity of roots to copper toxicity, as they are the first organs exposed to contaminants and consequently sustain the greatest damage. The presence of copper in the rhizosphere causes morphological alterations in the root apex, leading to shorter and thicker roots. Additionally, copper stress impairs root growth and the absorption of water and nutrients by decreasing the rate of mitotic division (\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e). Comparable effects were observed in Indian jute (\u003cem\u003eCorchorus capsularis\u003c/em\u003e L.) and \u003cem\u003eAegilops tauschii\u003c/em\u003e under copper stress (\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e). Foliar application of SA enhanced plant growth and markedly improved the fresh and dry biomass of shoots and roots in okra, which is consistent with similar findings observed in bean and \u003cem\u003eSalvia officinalis\u003c/em\u003e L. under copper stress (\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e). SA likely promotes vegetative growth by stimulating indole acetic acid (IAA) and gibberellin synthesis, while boosting stem and root development through improved nutrient uptake (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e). Foliar SNP mitigated copper toxicity, enhancing okra growth and yield. SNP\u0026rsquo;s role in alleviating HM stress and improving growth was also noted in perennial ryegrass and Chinese cabbage under cadmium toxicity (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e). Hajihashem et al. (2022) found that combined SA\u0026thinsp;+\u0026thinsp;SNP treatment enhanced plant growth by increasing metabolite synthesis and carbon fixation, while stimulating growth via cell wall acidification (\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e). In this study, simultaneous SNP\u0026thinsp;+\u0026thinsp;SA application increased okra growth, biomass, and height. In this study, copper toxicity markedly elevated the levels of H₂O₂, MDA, and cell death in both the shoots and roots of okra plants. Despite higher Cu accumulation in the roots, the shoot tissues exhibited greater MDA content, indicating their heightened sensitivity to Cu-induced oxidative damage. Similar increases in H₂O₂ and MDA under copper stress have been reported in \u003cem\u003eBoehmeria nivea\u003c/em\u003e (\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e) and \u003cem\u003eBrassica juncea\u003c/em\u003e (\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e), along with enhanced cell death in pea (\u003cem\u003ePisum sativum\u003c/em\u003e) roots (\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e). The application of 500 and 150 \u0026micro;M levels of SA and SNP significantly reduced cell death, MDA, and H₂O₂ levels in both the shoots and roots of okra plants exposed to copper toxicity. These findings highlight the effectiveness of these treatments in alleviating copper-induced oxidative stress. SA is believed to confer protection by inhibiting lipid peroxidation, maintaining membrane integrity, and enhancing the antioxidant defense system (\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e). Similar protective effects of SA have been reported in cotton under copper stress (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e), in soybean roots under aluminum toxicity (\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e), and in Canola subjected to arsenic stress (\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e), where reductions in MDA, H₂O₂, and cell death were observed. SNP functions as a signaling molecule that regulates the expression of antioxidant defense genes, thereby enhancing the production of enzymes that neutralize ROS. This action contributes to reduced oxidative damage, improved membrane stability, and a decrease in cell death (\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e). These findings align with similar results observed in plants such as soybean (\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e) and rice (\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e) under HMs stress. Additionally, the simultaneous application of SA and SNP in safflower under zinc stress led to a significant reduction in H₂O₂ and MDA levels in both the roots and shoots of okra (\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e). Under copper stress conditions, okra plants exhibited an effective adaptive response by increasing proline and soluble sugar content in both roots and shoots, with a more prominent increase observed in the roots. Proline accumulation, as an osmotic and oxidative stress protectant (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e), has been previously reported in \u003cem\u003eBoehmeria nivea\u003c/em\u003e (\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e) and \u003cem\u003eLinum usitatissimum\u003c/em\u003e (\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e). Additionally, an elevation in soluble carbohydrates, contributing to osmotic osmotic regulation and carbon storage, has been observed in \u003cem\u003eSpartina alterniflora\u003c/em\u003e under copper stress (\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e, \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e). The increase in soluble sugars may result from factors such as growth cessation, breakdown of polysaccharides like starch, non-photosynthetic sugar synthesis, and reduced exchange of photosynthetic products between plant parts. These results underscore the essential role of these compounds in plant adaptation to HMs stress(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). The evaluation of individual and joint treatments of SA and SNP in the roots and shoots of okra under copper stress, compared to the control, showed an increase in proline and soluble sugars. However, a noticeable decline in osmolyte levels under SA treatment was observed compared to the stress levels. This decrease in proline in the SA treatment is likely due to the fact that, in the presence of SA, there is less need for free proline as a stress protectant. A reduction in soluble sugars in plants such as \u003cem\u003eOryza sativa\u003c/em\u003e L. (Rice) (\u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e) and \u003cem\u003eHelianthus annuus\u003c/em\u003e L. (\u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e) treated with SA under copper stress has been reported. Ahmad et al. (2016) (\u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e) indicated that NO helps maintain cell turgor and water retention in plants by stimulating the accumulation of osmotic regulators, including proline and soluble sugars, thereby enhancing plant resilience against environmental stressors. In our study, the separate and combined application of SNP to the roots and leaves of okra under copper stress resulted in increased proline and soluble carbohydrates levels relative to the control. Our findings are consistent with those reported for tomato (\u003cem\u003eSolanum lycopersicum\u003c/em\u003e) (\u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e72\u003c/span\u003e). The increase in protein content in the shoot and root organs of okra plants under copper stress may be attributed to the compensatory synthesis of proteins that have been inactivated by binding to HMs, or to the enhanced production of stress-related proteins such as heat shock proteins (HSPs) and enzymes involved in antioxidative defense (\u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e73\u003c/span\u003e). This result has similarly been documented for wheat variety (\u003cem\u003eTriticum aestivum\u003c/em\u003e L.) (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). In the present study, both separate and combined applications of SNP and SA led to an increase in protein content in the shoot and root organs of okra plants under copper stress. This increase seems to be related to the role of SA in strengthening the antioxidant system and membrane protection, in addition to the effect of NO released from SNP in reducing oxidative stress and maintaining cellular redox homeostasis. The results are consistent with findings reported in \u003cem\u003eOryza sativa\u003c/em\u003e L. (\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e). Antioxidants, both enzymatic and non-enzymatic, are integral components of the plant defense system, developed to eliminate excess ROS and preserve cellular redox homeostasis (\u003cspan citationid=\"CR74\" class=\"CitationRef\"\u003e74\u003c/span\u003e, \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e75\u003c/span\u003e). In the present study, copper stress led to an increased activities of CAT, POD, and SOD in both shoot and root tissues of okra, which is consistent with findings reported for \u003cem\u003eHibiscus cannabinus\u003c/em\u003e L. under similar conditions (\u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e76\u003c/span\u003e). Similarly, a study by Wang et al. (2024) revealed that copper toxicity triggered a significant increase in antioxidant enzyme activity in both the shoots and roots of \u003cem\u003eAegilops tauschii\u003c/em\u003e (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e). Exposure of okra plants to SA and SNP, either individually or in combination, significantly enhanced the activity of antioxidant enzymes (CAT, POD, and SOD) in both shoot and root tissues under copper-induced stress. This enhancement was particularly pronounced in the combined Cu\u0026thinsp;+\u0026thinsp;SA treatment, highlighting the protective role of SA in reducing oxidative stress induced by HMs exposure. Previous studies have also demonstrated that SA improves the efficiency of the plant\u0026rsquo;s antioxidant system by suppressing ROS generation and mitigating lipid oxidative stress (\u003cspan citationid=\"CR77\" class=\"CitationRef\"\u003e77\u003c/span\u003e), in addition to inducing antioxidant enzymes or regulation of their gene expression (\u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e78\u003c/span\u003e). A similar increase in antioxidant enzyme activity in response to SA treatment has also been reported in wheat (\u003cspan citationid=\"CR79\" class=\"CitationRef\"\u003e79\u003c/span\u003e). SNP as a NO donor enhances the plant's defense mechanisms and mitigates damage caused by various abiotic factors by inducing the expression of antioxidant-related genes (\u003cspan citationid=\"CR80\" class=\"CitationRef\"\u003e80\u003c/span\u003e). In the present study, SNP application in okra under copper stress led to an increase in antioxidant enzyme activity, a response that has also been observed in sorghum under copper stress (\u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e72\u003c/span\u003e). In our study, the simultaneous application of SA and SNP led to an increase in antioxidant enzyme activity in okra plants, a finding that aligns with the results reported by Mostofa et al. (2019) (\u003cspan citationid=\"CR81\" class=\"CitationRef\"\u003e81\u003c/span\u003e) in rice plants under cadmium stress. This current research demonstrated that copper accumulation in okra plants under copper stress was significantly greater in the roots compared to the shoots. This indicates a slow movement of copper upward from roots to shoots and suggests that okra is not a hyperaccumulator species. These findings are consistent with those of Ibrahim (2017) (\u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e82\u003c/span\u003e) who reported greater copper accumulation in the root system than in the stem tissues of \u003cem\u003eGynura procumbens\u003c/em\u003e (Lour). Furthermore, in okra, increasing copper concentrations in the growth medium led to a reduction in essential nutrients such as Mg, Zn and Fe likely due to competitive uptake mechanisms. These observations align with those of Es-sbihi et al. 2020 (\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e), who investigated \u003cem\u003eSalvia officinalis\u003c/em\u003e under copper stress. In this research, foliar application of SA, SNP and their combination SA\u0026thinsp;+\u0026thinsp;SNP significantly increased the content of Mg, Zn, and Fe while reducing Cu accumulation in the roots and shoot parts of okra plants under Cu stress. These results indicate the inhibitory effect of SA and SNP on the process of Cu uptake and transfer to different plant parts. Moreover, treatment with SA and SNP reduced Cu toxicity by decreasing the transfer of this element and enhancing antioxidant enzyme activity in the plant. Similar results have been confirmed in cotton (\u003cem\u003eGossypium hirsutum\u003c/em\u003e) and rice (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e, \u003cspan citationid=\"CR83\" class=\"CitationRef\"\u003e83\u003c/span\u003e). A research by Bai et al. 2015 (\u003cspan citationid=\"CR84\" class=\"CitationRef\"\u003e84\u003c/span\u003e) showed that SA treatment increased the levels of Mg, Zn, Mn, and Fe in \u003cem\u003eLolium perenne\u003c/em\u003e under cadmium stress. It has been reported that SNP reduced heavy metal accumulation and increased the levels of Fe, Mn, and Zn in soybean plants under mercury stress (\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e). This effect was likely due to an increase in internal NO content, which activates membrane transporters, leading to metal removal and increased absorption of essential mineral elements (\u003cspan citationid=\"CR85\" class=\"CitationRef\"\u003e85\u003c/span\u003e). In another research, it was confirmed that the combination of SA and SNP significantly increased the levels of essential elements such as K, Ca, Zn, Fe, and Mn in rose plants under alkaline stress (\u003cspan citationid=\"CR86\" class=\"CitationRef\"\u003e86\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrated that foliar application of SA and SNP whether applied individually or in combination significantly enhanced the tolerance of okra plants to copper stress. These protective effects were associated with reduced copper accumulation in plant tissues, mitigation of copper-induced oxidative stress, and improved regulation of nutrient uptake. Treatment with SA and SNP led to a decrease in cellular damage markers (e.g., MDA and H₂O₂), preservation of membrane integrity, enhancement of the antioxidant defense system, and improved uptake of essential nutrients. Overall, the results of the comparative analysis indicated that SA was more effective than SNP in alleviating copper toxicity and enhancing okra\u0026rsquo;s physiological tolerance.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eApproval for plant experiments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll experimental procedures involving plants were carried out in accordance with institutional, national, and international regulations and ethical standards.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and /or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eDantas, T. L., Alonso Buriti, F. C., \u0026amp; Florentino, E. R. (2021). 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Plant Physiol\u003c/em\u003e. \u003cstrong\u003e62(2):\u003c/strong\u003e 237-245. http://doi.org/10.1134/S1021443715020028. \u003c/li\u003e\n\u003cli\u003eXu, J., Wang, W., Yin, H., Liu, X., Sun, H., \u0026amp; Mi, Q. (2010). Exogenous nitric oxide improves antioxidative capacity and reduces auxin degradation in roots of \u003cem\u003eMedicago truncatula\u003c/em\u003e seedlings under cadmium stress. \u003cem\u003ePlant Soil. \u003c/em\u003e\u003cstrong\u003e326,\u003c/strong\u003e 321-330. http://doi.org/10.1007/s11104-009-0011-4.\u003c/li\u003e\n\u003cli\u003eMoazam Babasheikhali, M., Jabbarzadeh, Z., Amiri, J., \u0026amp; Barin, M. (2020). Impact of salicylic acid and nitric oxide on improving growth and nutrients uptake of rose in alkaline soil conditions\u003cem\u003e. J. Plant Nutr.\u003c/em\u003e \u003cstrong\u003e43(5),\u003c/strong\u003e 667-681. http://doi.org/10.1080/01904167.2019.1701023.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"antioxidant enzymes, essential elements, nitric oxide, oxidative stress","lastPublishedDoi":"10.21203/rs.3.rs-6651901/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6651901/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCopper (Cu) stress is one of the \u003cem\u003eabiotic stressors\u003c/em\u003e that can severely damage plant cells. At elevated concentrations, copper becomes a toxic element within plants, triggering the generation of oxidative molecules and disrupting enzymatic activities. Salicylic acid (SA) is a plant growth regulator, while sodium nitroprusside (SNP) is a nitric oxide-releasing compound. Both play critical function\u003cb\u003es\u003c/b\u003e in modulating plant metabolism, growth, development, and mechanisms.They also influence gene expression and signaling pathways, with effects that may be either beneficial or detrimental depending on the context. The application of these compounds at appropriate doses significantly contributes to alleviating abiotic stresses in various plant species, particularly by counteracting the toxic effects. In this study, the individual and simultaneous effects of SA (500 \u0026micro;M) and SNP (150 \u0026micro;M), alongside varying concentrations of copper sulfate (600 and 1200 \u0026micro;M), were evaluated on the physiological and morphological responses of the Clemson variety of okra (\u003cem\u003eAbelmoschus esculentus\u003c/em\u003e) in a hydroponic culture system. The experiments were conducted using a completely randomized design with three replicates per treatment. The results revealed that high copper concentrations reduced growth parameters and essential nutrient levels, while increasing malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and cell death, protein content, proline, soluble carbohydrates, and activities of enzymes, along with copper content in the shoots and roots of okra plants compared to the control. In contrast, foliar application of SA and SNP improved the uptake of essential elements, increasing Mg (up to 41%), Fe (51%), and Zn (50%). It also enhanced antioxidant enzyme activities (67\u0026ndash;92%) and significantly reduced copper concentration (58%), MDA content (15%), H₂O₂ levels (26%), and cell death (49%) in the shoots and roots of okra plants. Therefore, based on the results, the individual and combined application of SA and SNP significantly mitigated the adverse effects of copper sulfate stress, improving tolerance of okra plants. According to the findings of this study SA demonstrated a considerably greater effect compared to SNP in in enhancing the resistance of okra plants to copper-induced stress.\u003c/p\u003e","manuscriptTitle":"Protective Role of Salicylic Acid and Sodium Nitroprusside Foliar Application Against Copper Stress in Okra (Abelmoschus esculentus)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-21 18:11:40","doi":"10.21203/rs.3.rs-6651901/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-08-05T06:14:42+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-01T01:54:33+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"267237065286465002888076561517098889425","date":"2025-07-19T05:55:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-18T10:02:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"161903523756513122391702882017582514280","date":"2025-07-17T12:36:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"31068857724422041759426876821234879086","date":"2025-07-17T11:47:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"65738716929530148123776738289413591800","date":"2025-07-17T05:31:46+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-17T05:14:14+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-06-19T10:54:59+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-29T13:57:26+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-22T20:24:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-05-22T20:23:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3dc2217d-f9ce-4555-b759-43b160166ed5","owner":[],"postedDate":"July 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":51860853,"name":"Biological sciences/Plant sciences"},{"id":51860854,"name":"Biological sciences/Plant sciences/Plant physiology"},{"id":51860855,"name":"Biological sciences/Plant sciences/Plant stress responses"}],"tags":[],"updatedAt":"2025-09-08T16:01:55+00:00","versionOfRecord":{"articleIdentity":"rs-6651901","link":"https://doi.org/10.1038/s41598-025-17608-8","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2025-09-01 15:57:16","publishedOnDateReadable":"September 1st, 2025"},"versionCreatedAt":"2025-07-21 18:11:40","video":"","vorDoi":"10.1038/s41598-025-17608-8","vorDoiUrl":"https://doi.org/10.1038/s41598-025-17608-8","workflowStages":[]},"version":"v1","identity":"rs-6651901","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6651901","identity":"rs-6651901","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}