Effects of potassium management on enzyme activity and cotton fiber cellulose content

Effects of potassium management on enzyme activity and cotton fiber cellulose content | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Effects of potassium management on enzyme activity and cotton fiber cellulose content Fabio Rafael Echer, Vinicius José Souza Perez, Giuliano Oliveira Carnevalli Baltazar, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2325912/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Potassium (K) is prone to be washed out of plant tissues independent of mineralization since it is not strongly bound to organic structures in the plant. Therefore, cover crops can enhance K cycling in cropping systems increasing the nutrient use efficiency by taking it up deep in the soil profile and releasing it on the soil surface. However, it is not clear if this cycling would have an effect on cotton morphophysiology, enzyme activity, and eventually on fiber quality. Results Cotton leaf area index was increased late in the season by K, with small differences between fertilized treatments, but was highest at full bloom when at least part of the K was applied to cotton Consequently, the enzymatic activity and accumulation of cellulose in the cotton fiber were also increased. Conclusions Potassium fertilization improves cotton physiological parameters such as leaf area index, but the effect on enzyme activity depends on the enzyme and on the cotton cultivar. Early cellulose accumulation in the fiber is favored by potassium fertilization and cotton rotation with ruzigrass. Gossypium hirsutum L. enzyme regulations leaf area index stomata conductance Figures Figure 1 Figure 2 Figure 3 Figure 4 Background Depending on crop yield, cotton K uptake ranges from 190 to 415 kg ha − 1 (Vieira et al. 2018; Rosolem et al. 2012 ; Rochester et al. 2007). The maximum uptake rate of 3.2 kg ha − 1 day − 1 was observed during boll filing stage (~ 115 DAE), but around 61% of the K was taken up during flowering in a high yielding field in Australia (Rochester et al. 2012). Potassium exports in fibers and seeds ranges from 15–21% of the total taken up, considering lint yields from 1,000 to 2,400 kg ha − 1 (Rochester et al. 2007). The fruit is the dominant K drain in the plant (Rosolem and Mikkelsen 1991 ). K translocation to the reproductive organs peaks during fruit development (Ali et al. 2018 )d accumulates in cotton burs. Potassium plays an important role in plant metabolism, growth, development and yield. It is essential for the optimal functioning of the plant's photosynthetic apparatus due to its role in stomata regulation, enzyme activation, RuBisCO activity and chlorophyl concentration (Dana et al. 2016 ; Wang et al. 2017; Shabala 2017 ; Parveen et al. 2020). Potassium also activates enzymes related to sucrose and starch, which is mainly responsible for carbon metabolism (Kahrizi et al. 2010 ; Ali et al. 2018 ; Parveen et al. 2020). The deficiency of K impairs leaf area expansion and CO 2 assimilation capacity (Gerardeaux et al. 2010 ), as well as numerous physiological functions, including water relations, enzymatic activation, charge balance, stress resistance an eventually cotton growth and yield (Oosterhuis et al. 2013 ). Fiber quality is essential for cotton comercialization, and K deficiency can result in less cellulose deposition on the secondary fiber wall, harming fiber maturity, micronaire, length, and uniformity (Hu et al. 2018 ). The deficiency of K results in an early maturing plant, with shorter cycle (Silva et al. 1995), decreased seed and boll weights and fiber yield (Pettigrew et al. 1996 ; Yang et al. 2012 ). Fiber strength can be decreased by K deficiency due to the nutrient role in building “bridges” between cellulose chains in the cotton fiber (Lima and Bélot 2019). There are three important enzymes related to fiber development in cotton: sucrose synthase (SuSy), sucrose phosphate synthase (SPS) and the soluble acid invertase (SAI). A decrease in activity of key enzymes such as sucrose synthase (SuSy), can affect cellulose deposition in the fiber, and consequently, fiber strength, short fiber index and maturity (Raphael et al. 2019). Sucrose synthase (SuSy) plays two fundamental roles: sucrose synthesis and decomposition (Tung et al. 2018 ). Acid invertase acts on the hydrolysis of sucrose to glucose and fructose (Hu et al. 2015 ) and sucrose phosphate synthase (SPS) is linked to the regulation of the carbon partition between sucrose and starch in the leaves (Huber and Huber 1996). The activity of these enzymes is dependent on K nutrition (Hafeez et al. 2019 ; Hu et al. 2015 ). Therefore, K regulates photoassimilation and translocation simultaneously with the enzyme activities (Zahoor et al. 2017 ). When K deficiency occurs during fiber elongation, the decrease in turgor pressure results in shorter fibers (Rosolem and Bogiani 2014 ). As this nutrient is associated with sugar transport in the plant, it is likely that K deficiency may affect the deposition of cellulose microfibrils on the secondary wall in cotton fibers, thus decreasing fiber resistance and micronaire. Sandy soils show low natural fertility, water retention, and cation exchange capacity (CEC) due to the low levels of organic matter and clay, and are prone to K leaching. Potassium chloride, the main source of K for agriculture, was shown to have high mobility in the soil profile, mainly in sandy soils with low CEC (Werle et al. 2008 ) because K adsorption to soil colloids is low (Duiker and Bleeg 2006). Since drainage is fast in sandy soils, K percolation in the soil profile below the rooting zone can impair fertilizer use efficiency during the rainy season (Rosolem et al. 2006 ). To avoid K loss, it has been traditionally recommended to split rates above 50 kg ha − 1 of K 2 O (Foloni and Rosolem 2008 ; Bernardi et al. 2009 ). Antoher strategy suggested to improve fertilizer use efficiency in sandy soils is applying fertilizer to cover crops such as grasses of the genera Urochloa grown before cotton, because the K taken up returns to the soil mimicking a slow-release fertilizer (Echer et al. 2020 ). Therefore, we hypothesize that the application of K to the cover crop grown before cotton is as efficient as that applied during the growing crop in the physiological aspects and in the efficient use of fertilizer. The application of K to ruzigrass grown as a cover crop before cotton has been shown to be a valid tool to enhance K use efficiency in the system. Now, we hypothetised that this modification in the managemnet of K fertilization in cotton has no effect on enzimatic activity and cotton fiber cellulose content compared to K applied to cotton. The aim of this work was to assess the leaf area index, enzymatic activity of sucrose metabolism related enzymes and cellulose content in two cotton cultivars under different K fertilizer managements and how the use of ruzigrass as a cover crop would interfere in these processes. Results Cultivars had no significant effect on LAI; hence, the results in Fig. 2 are averaged over cultivars FM 913GLT and FM 983GLT. In the first season, at 60 DAE LAI was higher when K was applied to cotton without ruzigrass, just to ruzigrass or split into ruzigrass and cotton as compared with the other tratments (Fig. 2 a). In the second year, there was no difference between treatments at 30 DAE, but at 60 and 90 DAE K fertilization in cotton without ruzigrass LAI was higher, and lower in the presence of ruzigrass without K (Fig. 2 b). At 120 DAE, a reduction in LAI was observed in the treatment where there was no K and ruzigrass, and it was lower when K was applied to ruzigrass. SAI activity in cotton leaves was higher when K fertilization was applied on ruzigrass + cotton (58K on RZ + 58 K on C) and when it was performed fully on cotton without ruzigrass on early cultivar (FM 913GLT) but for the late cultivar (FM 983GLT), SAI activity was increased only by K fertilization on cotton without ruzigrass (Fig. 4 a FM 913GLT). In both cultivars, the lowest SAI activity was observed in the absence of K and ruzigrass. Early cultivar FM 913GLT had higher SAI activity when K was split in ruzigrass and cotton, but the full K application on cotton without ruzigrass resulted in higher SAI activity in the late cultivar (FM 983GLT). The greatest SPS activity was found where K fertilization was applied entirely on cotton and it was slightly higher in the presence of ruzigrass for the late cultivar. The lowest activity was observed in the absence of K and in ruzigrass (0K + RZ) (Fig. 3 b). SPS activity in the early cultivar was improved by K fertilization on cotton after ruzigrass (116K + RZ). Furthermore, the early cultivar FM 913GLT showed greater SPS activity in most K managements. For the late cultivar (FM 983GLT), full K fertilization with (116K + RZ) or without ruzigrass (116K) resulted in higher SPS activity. The highest SuSy activity in both cultivars was found when K was applied to cotton in the absence of ruzigrass (116K) (Fig. 4 c), while the lowest was observed in the absence of K fertilization and ruziziensis (0K). Also, late cultivar FM 983GLT had higher SuSy activity in most treatments, but the early cultivar showed higher SuSy activity when receiving K in the absence of ruzigrass (116K). In both cultivars, when K was applied on ruzigrass and cotton, Susy activity increased. Splitting K fertilitazion half on ruzigrass and half on cotton increased the cellulose content in the cotton fiber 24 DAA. It is interesting that even applying 116 kg ha − 1 of K to cotton in the absence of ruzigrass, the fiber cellulose content was similar to those in the absecence of K (Fig. 5a). At 48 DAE, when the cellulose contents were higher for both cultivars, there was no difference in cellulose content between treatments (Fig. 5b). However, the early cultivar (FM 913GLT) accumulated more cellulose in the fiber at 24 DAA than FM 983 GLT. Discussion Potassium management did not affect LAI early in the cycle in both seasons (Fig. 2 ), probably because cotton canopy growth is slow at this stage, as the plant invests most of the carbohydrates to develop its root system (Echer et al. 2019 ). However, at 60 and 90 DAE in the first season and 60, 90 and 120 DAE in the second season, LAI was higher when the plant was fertilized with K, as a result of the increased leaf area and life span, as the leaf's life is reduced by K deficiency (Wrigth 1999). SAI catalyzes the hydrolysis of sucrose into glucose and fructose (Winter Huber 2000); SPS is directly related to sucrose synthesis from carbon fixed by photosynthesis (Mendicino 1960 ), and SuSy's main function is to cleave sucrose for starch synthesis and cell wall construction (Déjardin et al. 1997; Nakai et al. 1999 ). Our results show that potassium fertilization was essential to keep the activities of enzymes involved in carbohydrate metabolism (SAI, SPS and SuSy) (Fig. 4 ). In addition, the increase in the activity of these enzymes is potentially linked to K leaf concentration (Hu et al. 2017 ; Zahoor et al. 2017 ; Tung et al. 2018 , Ali et al. 2018 ). Studies have reported changes in the leaf sucrose or starch contents and increased enzyme activity and carbohydrate metabolism by K application in cotton (Wang et al. 2012 ; Hu et al. 2015 ; Zahoor et al. 2017 ; Ali et al. 2018 ). There is a strong relationship between cell elongation and leaf K concentration, since the hormones that stimulate cell elongation are highly dependent on adequate levels of K in plant tissues (Cakmak 2005 ). The qualitative characteristics of cotton fibers are positively influenced by an adequate supply of K, as this nutrient regulates the crop cycle, maintains the leaf area, and provides greater cellulose deposition on the inner walls of the fibers improving micronaire index (Carvalho et al. 2006; Hafeez et al. 2019 ). Indeed, during the fiber-thickening process, SAI, SPS and SuSy serve as the main enzymes for cellulose synthesis, and their activities are highly dependent upon K application rate (Zahoor et al. 2017 ; Tung et al. 2018 ; Ali et al. 2018 ), corroborating our results and showing that K application in cotton resulted in increased enzymatic activity concomitantly with the increase in cellulose deposition in the fibers (Figs. 4 and 5). Conclusion Potassium fertilization improves physiological parameters such as LAI in a year with a regular rainfall distribution. The absence of K impairs activity of the enzymes SAI, SPS and SuSy, but the effect is cultivar dependent. Early cellulose accumulation in the fiber is favored when cotton is grown after ruzigrass. Methods Field experiments were conducted in the 2016/17 and 2017/18 cropping seasons in Presidente Bernardes, São Paulo, Brazil, 22º07'32" S and 51º23'20" W, 475 m asl. The soil is a typic Rhodustult, sandy loam (USDA 2010). The climate is tropical with dry winters and wet, hot summers. Soil samples were taken at the depths of 0 to 20 cm and 20 to 40 cm on May 05, 2016, for chemical analysis as in Raij et al. (2001). Selected chemical and particle size distribution of the soil are in Table 1 . Lime (45% of CaO and 4.9% of MgO) was broadcast on the soil surface at 1,400 kg ha − 1 in September 2016 and 2,000 kg ha − 1 in October 2017. Rainfall, maximum and minimum temperatures, and vapor pressure deficit during the experiment are shown in Fig. 1 . Table 1 Selected chemical properties and particle size distribution of the soil depth pH (CaCl 2 ) SOM P (Resin) S Al 3+ H + Al K + Ca 2+ Mg 2+ CEC cm g dm − 3 mg dm − 3 mmol c dm − 3 0–20 4.7 13.6 2.8 4.0 0.6 17.6 0.8 7.3 5.1 30.7 20–40 4.8 11.6 2.0 3.3 2.3 18.6 0.8 6.5 4.4 30.3 B Cu Fe Mn Zn m BS sand Silt clay ------------------mg dm − 3 ------------------- ---%--- --------g kg − 1 --------- 0–20 0.34 2.0 26.0 0.9 0.4 4.3 42.6 848 36 116 20–40 0.41 1.4 31.5 1.0 0.3 16.4 38.6 841 23 137 The treatments were an early (FM 913GLT) and a late (FM 983GLT) cotton cultivar and six K fertilization schemes (Table 2 ). Treatments were repeated in the same plots in both seasons. The experimental design was a 2 x 6 factorial in complete randomized blocks with five replicates. Each plot had four 7.0-m cotton rows spaced 0.8 m from each other. The two outer rows and 1.0 at the end of each row were considered borders and not included in evaluations. Table 2 Scheme of cotton K fertilization Treatments Ruzigrass (RZ) K rate Time of K fertilization 0K no 0 - 116K no 116 kg ha − 1 58 kg ha − 1 applied 30 DAE and 58 kg ha − 1 at 45 DAE 0K + RZ yes 0 - 116K on RZ yes 116 kg ha − 1 applied on RZ vegetative stage (90 DAE) 58K on RZ + 58K on C yes 116 kg ha − 1 58 kg ha − 1 applied on RZ vegetative stage and 58 kg ha − 1 on cotton 30 DAE 116K on C + RZ yes 116 kg ha − 1 58 kg ha − 1 30 DAE and 58 kg ha − 1 45 DAE DAE: days after emergence Table 3 Eigenvalues of all variables analyzed of FM 913GLT and FM 983GLT under different K management and the use of ruzigrass Total variance explained (%) FM 913GLT FM 983GLT LAI 30 − 0.6417 -0.0285 LAI 60 -0.4406 -0.3578 LAI 90 -0.8885 -0.7625 LAI 120 -0.9217 -0.7661 Gs F1 -0.4848 -0.0170 Gs F7 -0.0224 -0.5170 Gs C2 -0.6766 -0.2506 SAI -0.7899 -0.8911 SPS -0.8047 -0.6714 SUSY -0.7150 -0.8713 Cellulose -0.6132 -0.5821 Ruzigrass was sown on May 05, 2016, and June 06, 2017 using 14 kg ha − 1 pure viable seeds. Potassium fertilizer was applied to the grass in the corresponding treatments early September each year, using potassium chloride. Ruzigrass was desiccated on November 1, 2016 and November 6, 2017, using glyphosate (1.92 g ha − 1 a.i.). Ruzigrass averaged 5.6 Mg ha − 1 of dry biomass. Cotton was sown on December 9, 2016, and November 23, 2017. Phosphorus was applied at 56 kg ha − 1 and N at 30 kg ha − 1 as mono ammonium phosphate at cotton planting. The rate of 140 kg ha − 1 of N was side dressed and equally split 35 and 45 days after plant emergence (DAE), using ammonium sulphate and urea, respectively. Boric acid was sprayed at 2.0 kg ha − 1 split into 4 weekly applications from the first flower. Weed, pests, and diseases were controlled according to standard farm practices in São Paulo State. Seven days before harvest plants were defoliated with Tidiazurom (60 g ha − 1 a.i.) + Diuron (30 g ha − 1 a.i). Cotton was handpicked 141 and 132 DAE in 2016/17 and 2017/18, respectively. Leaf area index 1st and 2nd season Leaf area index was measured at 30, 60, 90, and 120 days after emergence using a ceptometer (Accupar LP-80 – Decagon Devices) in three sub-samples per plot in both seasons. Enzyme extraction and assay – 2nd season At mid flowering (F6/F7 stage – Marur and Ruano 2001 ), twelve plants per plot had their first position flowers tagged, and 24 days later (24 DAA – days after anthesis) four bolls and their leaves were collected. At 48 DAA only bolls were collected since leaves were absent. This material was ground to a fine powder in liquid nitrogen. Leaf samples (0.5 fresh weight) and 3.5 mL of extraction buffer (50 mM Hepes-KOH, pH 7.5, 10 mM MgCl 2 , 2 mM EDTA, 5 mM DTT, 2% (w/v) PVP) were ground into a homogenate in an ice bath (Grof et al. 2007). The samples were centrifuged subsequently at 12,000 xg for 20 minutes at 4 ºC. The supernatant was gradually added with Dowex 1x4 and then centrifuged at 12,000 xg for 10 minutes at 4 ºC. The supernatant was collected and the Sucrose Phosphate Synthase (SPS - EC 2.4.1.14 ), Sucrose Synthase (SuSy - EC 2.4.1.13 ) and Soluble Acid Invertase (SAI - EC 3.2.7.26 ) were analyzed. All procedures were done at 4 ºC. Protein measurement was performed as in Bradford ( 1976 ), using bovine serum albumin as standard. SPS activity was determined as in Huber and Huber ( 1991 ). A 50 µL enzyme solution alicote was added to 50 µL solution contained (100 mM Hepes-NaOH buffer, 50 mM MgCl 2 , 20 mM UDPG, 5 mM fructose 6-phosphate, and 17.5 mM glucose 6-phosphate. The reaction was started by the addition of extract and incubated at 25°C for 10 min. After stopping the reaction with 100 µL of 5 M KOH and 10 min of heating at 100°C, followed by 1 mL of 0.14% (w/v) anthrone in 80% (v/v) H 2 SO 4 , was added before 40 min of incubation at 40°C (King et al. 1997 ). SUC-6-P (and SUC) content was determined by comparing the A 628 to that of a standard curve (0-200 nmol of SUC). SuSy activity (synthetic direction) was determined by replacing fructose 6-phosphate with fructose in the same way as SPS activity. The unit of enzyme activity was expressed as µmol µmol Suc min –1 mg –1 prot. The SAI activity was determined as in King et al ( 1997 ). Shortly, 0.2 mL enzyme solution was added into 0.8 mL reaction solution (pH 4.8 0.1M Na2HPO4–0.1 M sodium citrate, 0.1 M sucrose), and reacted at 37°C for 30min. Determination of cellulose in cotton fiber – 2nd season Fruit samples were taken from the first position (P1) of the 10th sympodial branch 24 and 48 DAA and dried in a forced-air oven at 65 ºC for 96 hours. Determinations were conducted in three replications, according to Van Soest et al. ( 1991 ). The acid-detergent fiber (ADF) content was determined using an acid detergent (trimethylammonium bromide, standardized sulfuric acid. After examining the ADF content, the cellulose content was assayed in cotton samples using a standardized solution of sulfuric acid. Statistical analysis After testing for homogeneity and normality, data were submitted to ANOVA. The experiment was arranged in a complete randomized block design in a 2 x 6 factorial scheme (cultivars x K management) and five replicates. The data were analyzed with three-way (cultivar, K management and year) analysis of variance and Tukey test ( P < 0.05) was used to compare treatment means. When the differences between cultivars were not significant, their averages were presented and discussed. Multivariate analysis was performed via principal component analysis (PCA) to verify the grouping of the different responses to K fertilizer management and the use of ruzigrass in the second year (2017/2018). Considering that the measurement units differed between variables, the data were log-transformed to reduce the effect of the numeric scale (McGarigal et al. 2000 ). The ordination graphic (with two major components) was demarcated by two axes designated as the first (PC1) and second (PC2) principal components. Declarations Ethics approval and consent to participate : Not applicable Consent for publication : Not applicable Availability of data and materials : Not applicable Competing interests: The authors declare that they have no competing interests. Funding: Foundation for Research Support of the State of São Paulo (FAPESP) (grant 2016/16736-4). Fundação Agrisus (grant PA 1918/16) and by APPA (São Paulo Cotton Grower´s Association). Authors' contributions: FRE methodology, writing original draft, formal analysis, data curation, visualization and supervision. VJSP, GOCB, and GRAS methodology, writing original draft, formal analysis, data curation. ALM writing original draft. PHG writing original draft, formal analysis. CAR writing original draft, formal analysis. Acknowledgements: The authors thank the Foundation for Research Support of the State of São Paulo (FAPESP) for their support through a Master´s scholarship granted to Peres, V.J.S. (grant 2016/16736-4). This work was partially funded by Fundação Agrisus (grant PA 1918/16) and by APPA (São Paulo Cotton Grower´s Association). References Amorim JSL. Correlação de Potássio Mehlich-1 com Potássio da solução de solos sob diferentes níveis de adubação. https://releia.ifsertao-pe.edu.br/jspui/bitstream/123456789/573/1/JANICLECIA%20SANTOS%20LIMA%20AMORIM.pdf (2019). Accessed 17 Mar 2022. Ali S, Hafeez A, Ma X, et al. Potassium relative ratio to nitrogen considerably favors carbon metabolism in late-planted cotton at high planting density. Field Crops Res. 2018;223:48–56. https://doi.org/10.1016/j.fcr.2018.04.005 . Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976;72:248–54. https://doi.org/10.1016/0003-2697(76)90527-3 . Bernardi ACC, de Oliveira Júnior JP, Leandro WM, et al. Doses e formas de aplicação da adubação potássica na rotação soja, milheto e algodão em sistema plantio direto. Pesqui Agropecu Trop. 2009;39:158–67. Cakmak I. The role of potassium in alleviating detrimental effects of abiotic stresses in plants. J Plant Nutr Soil Sci. 2005;168:521–30. https://doi.org/10.1002/jpln.200420485 . Carvalho MCS, Ferreira ACB. Manejo de solos aptos à cotonicultura no cerrado. In: Freire EC, editor. Algodão no cerrado do Brasil. 2. ed.: Aparecida de Goiânia: Associação Brasileira dos Produtores de Algodão; 2007. pp. 193–224. Cassman KG, Kerby TA, Roberts BA, et al. Potassium nutrition effects on lint yield and fiber quality of Acala cotton. Crop Sci. 1990;30:672–7. https://doi.org/10.2135/cropsci1990.0011183X003000030039x . Clement-Bailey J, Gwathmey CO. Potassium effects on partitioning, yield, and earliness of contrasting cotton cultivars. Agron J. 2007;99:1130–6. https://doi.org/10.2134/agronj2006.0288 . Copeland L. (1990) Enzymes of sucrose metabolism. In: Lea, PJ, editor. Methods in Plant Biochemistry. 1990. p. 73–85. https://doi.org/10.1016/B978-0-12-461013-2.50011-3 . Dana S, Herdean A, Lundin B, et al. Retracted: Each of the chloroplast potassium efflux antiporters affects photosynthesis and growth of fully developed Arabidopsis rosettes under short-day photoperiod. Physiol Plant. 2016;158:483–91. https://doi.org/10.1111/ppl.12452 . Dejardin A, Rochat C, Wuillème S, et al. Contribution of sucrose synthase, ADP-glucose pyrophosphorylase and starch synthase to starch synthesis in developing pea seeds. Plant Cell Environ. 1997;20:1421–30. https://doi.org/10.1046/j.1365-3040.1997.d01-32.x . Duiker SW, Beegle DB. Soil fertility distributions in long-term no-till, chisel/disk and moldboard plow/disk systems. Soil Till Res. 2006;88:30–41. https://doi.org/10.1016/j.still.2005.04.004 . Echer FR, Peres VJS, Rosolem CA. Potassium application to the cover crop prior to cotton planting as a fertilization strategy in sandy soils. Sci Rep. 2020;10:20404. https://doi.org/10.1038/s41598-020-77354-x . Echer FR, Zanfolin PRL, Moreira ACM, et al. Root growth and carbohydrate partitioning in cotton subjected to shading in the initial phase. Cienc Rural. 2019;49:e20180749. https://doi.org/10.1590/0103-8478cr20180749 . Furlani E Jr, Silva NM, Buzetti S, et al. Extração de macronutrientes e acúmulo de massa seca de algodão cv. IAC 22. Cult Agron. 2001;10:71–87. Foloni JSS, Rosolem CA. Produtividade e acúmulo de potássio na soja em função da antecipação da adubação potássica no sistema plantio direto. Rev Bras Cienc Solo. 2008;32:1549–61. https://doi.org/10.1590/S0100-06832008000400019 . Gerardeaux E, Jordan-Meille L, Constantin J, et al. Changes in plant morphology and dry matter partitioning caused by potassium deficiency in Gossypium hirsutum L. Environ Exp Bot. 2010;67:451–9. https://doi.org/10.1016/j.envexpbot.2009.09.008 . Gormus O, El-Sabagh A, Islam MS. Optimizing yield and fiber quality of cotton under Mediterranean environment: managing nitrogen and potassium nutrition. J Exp Biol Agric Sci. 2016; 4:572–580. http://dx.doi.org/10.18006/2016.4(5 S).572.580Grof CP, Albertson PL, Bursle J, et al. Sucrose-phosphate synthase, a biochemical marker of high sucrose accumulation in sugarcane. Crop Sci. 2007; 47:1530–1539. https://doi.org/10.2135/cropsci2006.12.0825. Hafeez A, Ali S, Ma X, et al. Sucrose metabolism in cotton subtending leaves influenced by potassium-to-nitrogen ratios. Nutr Cycl Agroecosyst. 2019;113:201–16. https://doi.org/10.1007/s10705-019-09976-1 . Hu W, Yang J, Meng Y, et al. Potassium application affects carbohydrate metabolism in the leaf subtending the cotton ( Gossypium hirsutum L.) boll and its relationship with boll biomass. Field Crops Res. 2015;179:120–31. https://doi.org/10.1016/j.fcr.2015.04.017 . Hu W, Coomer TD, Loka DA, et al. Potassium deficiency affects the carbon-nitrogen balance in cotton leaves. Plant Physiol Biochem. 2017;115:408–17. https://doi.org/10.1016/j.plaphy.2017.04.005 . Hu W, Loka DA, Fitzsimons TR, et al. Potassium deficiency limits reproductive success by altering carbohydrate and protein balances in cotton ( Gossypium hirsutum L.). Environ Exp Bot. 2018;145:87–94. https://doi.org/10.1016/j.envexpbot.2017.10.024 . Huber SC, Huber JL. Regulation of maize leaf sucrosephosphate synthase by protein phosphorylation. Plant Cell Physiol. 1991;32:319–26. https://doi.org/10.1093/oxfordjournals.pcp.a078083 . Kahrizi D, Cheghamirza K, Kakaei M, et al. Heritability and genetic gain of some morphophysiological variables of durum wheat ( Triticum turgidum var. durum ). Afr J Biotechnol. 2010;9:4469–687. King SP, Lunn JE, Furbank RT. Carbohydrate content and enzyme metabolism in developing canola siliques. Plant Physiol. 1997;114:153–60. https://doi.org/10.1104/pp.114.1.153 . Langer K, Levchenko V, Fromm J, et al. The poplar K + channel KPT1 is associated with K + uptake during stomatal opening and bud development. Plant J. 2004;37:828–38. https://doi.org/10.1111/j.0960-7412.2003.02008.x . Lima JJ, Bélot JS. A fibra de algodão: qualidade e classificação. In: Bélot JS, Vilela PMCA, editors. Manual de boas práticas de manejo do algodoeiro em Mato Grosso. Cuiabá: Instituto Matogrossense do Algodão; 2020. pp. 382–99. McGarigal K, Stafford S, Cushman S. Multivariate Statistics for Wildlife Ecology Research. New York: Springer; 2000. p. 283. https://doi.org/10.1007/978-1-4612-1288-1 . Marur CJ, Ruano O. A reference system for determination of developmental stages of upland cotton. Revis Bras Oleag Fibr. 2001;5:313–7. Mendicino J. Sucrose phosphate synthesis in wheat germ and green leaves. J Biol Chem. 1960;235:3347–52. https://doi.org/10.1016/S0021-9258(18)64469-2 . Nakai T, Tonouchi N, Konishi T, et al. Enhancement of cellulose production by expression of sucrose snthase in Acetobacter xylinum . Proc Natl Acad Sci. 1999;96:14–8. https://doi.org/10.1073/pnas.96.1.14 . Oosterhuis DM, Loka DA, Raper TB. Potassium and stress alleviation: physiological functions and management of cotton. J Plant Nutr Soil Sci 2013; 176:331–43. https://doi.org/10.1002/jpln.20120 0414 . Parveen, Anwar-Ul-Haq M, Aziz T, et al. Potassium induces carbohydrates accumulation by enhancing morpho-physiological and biochemical attributes in soybean under salinity. Arch Agron Soil Sci. 2020;67:946–59. https://doi.org/10.1080/03650340.2020.1769075 . Pereira JRA, Rossi P Jr. Manual Prático de Avaliação Nutricional de Alimentos. Piracicaba: FEALQ; 1995. 34p. Pettigrew WT, Heitholt JJ, Meredith WR Jr. Genotypic interactions with potassium and nitrogen in cotton of varied maturity. Agron J. 1996;88:89–93. https://doi.org/10.2134/agronj1996.00021962008800010019x . Raphael JPA, Rosolem CA, Echer FR. Distribuição da produção no algodoeiro: conceitos, fatores ecofisiológicos, e implicações sobre a produtividade e sobre a qualidade da fibra. In: Bélot JS, Vilela PMCA, editors. Manual de boas práticas do algodoeiro em Mato Grosso. Cuiabá: Instituto Matogrossense do Algodão; 2020. pp. 112–34. Raij. Bvan.Análise química para avaliação da fertilidade de solos tropicais. Campinas. Instituto Agronômico de Campinas; 2001. 285p. Rosolem CA, Bogiani JC. Nutrição e estresses nutricionais em algodoeiro. In: Echer FR, editor. O algodoeiro e os estresses abióticos: temperatura, luz, água e nutrientes. Cuiabá: Instituto Matogrossense do Algodão; 2014. pp. 103–21. Rosolem CA, Mikkelsen DS. Potassium absorption ans partitioning in cotton as affected by periods of potassium deficiency. J Plant Nutr. 1991;14:1001–16. https://doi.org/10.1080/01904169109364259 . Rosolem CA, Echer FR, Lisboa IP, et al. Acúmulo de Nitrogênio, fósforo e potássio pelo Algodoeiro Sob Irrigação Cultivado em Sistemas Convencional e Adensado. Rev Bras Cienc Solo. 2012;36:427–66. https://doi.org/10.1590/S0100-06832012000200015 . Rosolem CA, Almeida DS, Rocha KF, et al. Potassium fertilization with humic acid coated KCl in a sandy clay loam tropical soil. Soil Res. 2017;56:244–51. https://doi.org/10.1071/SR17214 . Rosolem CA, Santos FPD, Foloni JSS, et al. Potássio no solo em conseqüência da adubação sobre a palha de milheto e chuva simulada. Pesq Agropec Bras. 2006;41:1033–40. https://doi.org/10.1590/S0100-204X2006000600020 . Saparov A, Eleshev R, Suleimenov B, et al. Effect of potassium chloride application for rice, cotton and potato in the irrigated zone of Kazakhstan. Better Crops Plant Food. 2013;97:23–5. Shabala L, Zhang J, Pottosin I, et al. Cell-type specific H + -ATPase activity in root tissues enables K + retention and mediates acclimation of barley ( Hordeum vulgare L.) to salinity stress. Plant Physiol. 2016;172:2445–58. https://doi.org/10.1104/pp.16.01347 . Shabala S. Signalling by potassium: another second messenger to add to the list? J Exp Bot. 2017;68:4003–7. https://doi.org/10.1093/jxb/erx238 . Silva NM, Carvalho LH, Cia E, et al. Seja doutor do seu algodoeiro. Informações Agronômicas, Piracicaba, 1995, n. 69, mar. (Encarte, Arquivo do Agrônomo n. 8). Tung SA, Huang Y, Ali S, et al. Mepiquat chloride application does not favor leaf photosynthesis and carbohydrate metabolism as well as lint yield in late-planted cotton at high plant density. Field Crops Res. 2018;221:108–18. https://doi.org/10.1016/j.fcr.2018.02.027 . Van Soest PV, Robertson JB, Lewis BA. Methods for Dietary Fiber, Neutral Detergent Fiber, and Nonstarch Polysaccharides in Relation to Animal Nutrition. J Dairy Sci. 1991;74:3583–97. https://doi.org/10.3168/jds.S0022-0302(91)78551-2 . Wang N, Hua H, Eneji AE, et al. Genotypic variations in photosynthetic and physiological adjustment to potassium deficiency in cotton ( Gossypium hirsutum ). J Photochem Photobiol B: Biol. 2012;110:1–8. https://doi.org/10.1016/j.jphotobiol.2012.02.002 . Wang Y, Wu WH. Regulation of potassium transport and signaling in plants. Curr Opin Plant Biol. 2017;39:123–8. https://doi.org/10.1016/j.pbi.2017.06.006 . Winter H, Huber SC. Regulation of sucrose metabolism in higher plants: localization and regulation of activity of key enzymes. Crit Rev Plant Sci. 2000; 31–67. https://doi.org/10.1080/07352680091139178 . Yang G, Tang H, Tong J, et al. Effect of fertilization frequency on cotton yield and biomass accumulation. Field Crops Res. 2012;125:161–6. https://doi.org/10.1016/j.fcr.2011.08.008 . Werle R, Garcia RA, Rosolem CA. Potassium leaching as affected by soil texture and potassium availability. Rev Bras Cienc Solo. 2008;32:2297–305. https://doi.org/10.1590/S0100-06832008000600009 . Zhao D, Oosterhuis DM, Bednarz CW. Influence of potassium deficiency on photosynthesis, chlorophyll content, and chloroplast ultrastructure of cotton plants. Photosynthetica. 2001;39:103–9. https://doi.org/10.1023/A:1012404204910 . Zahoor R, Dong H, Abid M, et al. Potassium fertilizer improves drought stress alleviation potential in cotton by enhancing photosynthesis and carbohydrate metabolism. Environ Exp Bot. 2017;137:73–83. https://doi.org/10.1016/j.envexpbot.2017.02.002 . 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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-2325912","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research","associatedPublications":[],"authors":[{"id":161383856,"identity":"9b139936-7695-4558-8a82-b5ce00a22b04","order_by":0,"name":"Fabio Rafael Echer","email":"","orcid":"","institution":"Unoeste: Universidade do Oeste Paulista","correspondingAuthor":false,"prefix":"","firstName":"Fabio","middleName":"Rafael","lastName":"Echer","suffix":""},{"id":161383857,"identity":"9d06af1c-9248-47ee-994e-6e428600f0b5","order_by":1,"name":"Vinicius José Souza Perez","email":"","orcid":"","institution":"Unoeste: Universidade do Oeste Paulista","correspondingAuthor":false,"prefix":"","firstName":"Vinicius","middleName":"José Souza","lastName":"Perez","suffix":""},{"id":161383858,"identity":"20dd55bd-aa49-4811-b56a-d197aaecfca0","order_by":2,"name":"Giuliano Oliveira Carnevalli Baltazar","email":"","orcid":"","institution":"Unoeste: Universidade do Oeste Paulista","correspondingAuthor":false,"prefix":"","firstName":"Giuliano","middleName":"Oliveira Carnevalli","lastName":"Baltazar","suffix":""},{"id":161383859,"identity":"f995f032-3dfa-4852-8a85-ee81129a4af3","order_by":3,"name":"Gustavo Ricardo Aguiar Silva","email":"","orcid":"","institution":"Unoeste: Universidade do Oeste Paulista","correspondingAuthor":false,"prefix":"","firstName":"Gustavo","middleName":"Ricardo Aguiar","lastName":"Silva","suffix":""},{"id":161383860,"identity":"7cfbb6ac-a59d-45fb-94df-46a7d3296aba","order_by":4,"name":"Adriana Lima Moro","email":"","orcid":"","institution":"Unoeste: Universidade do Oeste Paulista","correspondingAuthor":false,"prefix":"","firstName":"Adriana","middleName":"Lima","lastName":"Moro","suffix":""},{"id":161383861,"identity":"4c0a3b7b-3ecd-4b7d-a724-4acb277e1b87","order_by":5,"name":"Pedro Henrique Gorni","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAs0lEQVRIiWNgGAWjYNACAxsgwdh4gBQtaSAtDaRoYTgMJonTYs6/+NjngoLzdmvbDwNtqbGJJqjFcsaz5NkzDG4nbzuTCNRyLC23gZAWgxtnjJl5gFrMDgC1MDYcJlrLuWSz8w+J1XK+B6TlgJ3ZDWJtsZzBlgzUkpxgdgNoSwIxfjHnP3yYmeePnb3Z+fSHDz7U2BDhMIkEMJ0IVplASDlYC/8BMG1PjOJRMApGwSgYoQAA07ZE7xYhWawAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0002-3866-9215","institution":"UNESP: Universidade Estadual Paulista Julio de Mesquita Filho","correspondingAuthor":true,"prefix":"","firstName":"Pedro","middleName":"Henrique","lastName":"Gorni","suffix":""},{"id":161383862,"identity":"2ba7cf52-bab0-4c1f-b105-c7b7d072ff46","order_by":6,"name":"Ciro Antonio Rosolem","email":"","orcid":"","institution":"UNESP: Universidade Estadual Paulista Julio de Mesquita Filho","correspondingAuthor":false,"prefix":"","firstName":"Ciro","middleName":"Antonio","lastName":"Rosolem","suffix":""}],"badges":[],"createdAt":"2022-11-29 14:56:50","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2325912/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2325912/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":30632890,"identity":"859714be-ea17-4fff-9c87-3edf68c1dd9f","added_by":"auto","created_at":"2022-12-21 15:40:37","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":658661,"visible":true,"origin":"","legend":"\u003cp\u003eRainfall, maximum and minimum temperatures, and vapor pressure deficit during the experiment.\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-2325912/v1/4ad7877e433a5e538e714301.png"},{"id":30632891,"identity":"c50700b0-bf98-4b50-a842-97554fb97e05","added_by":"auto","created_at":"2022-12-21 15:40:37","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":265005,"visible":true,"origin":"","legend":"\u003cp\u003eCotton leaf area index (LAI) as affected by K management in the 2016/17 (a) and 2017/18 (b) seasons. Vertical bars show the least significant difference (Tukey test, \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-2325912/v1/132abd5315bc1764d2ba9f03.jpeg"},{"id":30633511,"identity":"3d6409a8-7067-4426-acf0-bdbeda093a91","added_by":"auto","created_at":"2022-12-21 15:48:37","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":205149,"visible":true,"origin":"","legend":"\u003cp\u003eActivity of soluble acid invertase (SAI), sucrose phosphate synthase (SPS), and sucrose synthase (SuSy) as affected by K fertilization management and cotton cultivars. Uppercase letters compare K management, and lowercase letters compare cultivars in each K management. (Tukey test, \u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-2325912/v1/346bb0067c644baa5685ff9e.jpeg"},{"id":30632889,"identity":"d88ea471-afb9-47ea-8b7c-fc4c19de6c0e","added_by":"auto","created_at":"2022-12-21 15:40:37","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":104527,"visible":true,"origin":"","legend":"\u003cp\u003eCellulose content in cotton fibers in the middle third of the plants (10\u003csup\u003eth \u003c/sup\u003enode) at 24 and 48 days after anthesis (DAA) as affected by K fertilizer management (a) and cotton cultivar (b). Uppercase letters compare K management (DAA) and lowercase letters compare boll age in each K management (a) or cultivar (b). (Tukey test,\u0026nbsp; \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-2325912/v1/ccdce54ef5aef3bc35e46244.jpeg"},{"id":33822934,"identity":"30a40f9f-609d-43ee-a587-6d398234bb87","added_by":"auto","created_at":"2023-03-06 08:14:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":758415,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2325912/v1/489902fc-9c8d-462a-89a2-e9f7437254be.pdf"}],"financialInterests":"","formattedTitle":"Effects of potassium management on enzyme activity and cotton fiber cellulose content","fulltext":[{"header":"Background","content":"\u003cp\u003eDepending on crop yield, cotton K uptake ranges from 190 to 415 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Vieira et al. 2018; Rosolem et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Rochester et al. 2007). The maximum uptake rate of 3.2 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e day\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was observed during boll filing stage (~\u0026thinsp;115 DAE), but around 61% of the K was taken up during flowering in a high yielding field in Australia (Rochester et al. 2012). Potassium exports in fibers and seeds ranges from 15\u0026ndash;21% of the total taken up, considering lint yields from 1,000 to 2,400 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Rochester et al. 2007). The fruit is the dominant K drain in the plant (Rosolem and Mikkelsen \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1991\u003c/span\u003e). K translocation to the reproductive organs peaks during fruit development (Ali et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e)d accumulates in cotton burs.\u003c/p\u003e \u003cp\u003ePotassium plays an important role in plant metabolism, growth, development and yield. It is essential for the optimal functioning of the plant's photosynthetic apparatus due to its role in stomata regulation, enzyme activation, RuBisCO activity and chlorophyl concentration (Dana et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Wang et al. 2017; Shabala \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Parveen et al. 2020). Potassium also activates enzymes related to sucrose and starch, which is mainly responsible for carbon metabolism (Kahrizi et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Ali et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Parveen et al. 2020). The deficiency of K impairs leaf area expansion and CO\u003csub\u003e2\u003c/sub\u003e assimilation capacity (Gerardeaux et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2010\u003c/span\u003e), as well as numerous physiological functions, including water relations, enzymatic activation, charge balance, stress resistance an eventually cotton growth and yield (Oosterhuis et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFiber quality is essential for cotton comercialization, and K deficiency can result in less cellulose deposition on the secondary fiber wall, harming fiber maturity, micronaire, length, and uniformity (Hu et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The deficiency of K results in an early maturing plant, with shorter cycle (Silva et al. 1995), decreased seed and boll weights and fiber yield (Pettigrew et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1996\u003c/span\u003e; Yang et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Fiber strength can be decreased by K deficiency due to the nutrient role in building \u0026ldquo;bridges\u0026rdquo; between cellulose chains in the cotton fiber (Lima and B\u0026eacute;lot 2019).\u003c/p\u003e \u003cp\u003eThere are three important enzymes related to fiber development in cotton: sucrose synthase (SuSy), sucrose phosphate synthase (SPS) and the soluble acid invertase (SAI). A decrease in activity of key enzymes such as sucrose synthase (SuSy), can affect cellulose deposition in the fiber, and consequently, fiber strength, short fiber index and maturity (Raphael et al. 2019). Sucrose synthase (SuSy) plays two fundamental roles: sucrose synthesis and decomposition (Tung et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Acid invertase acts on the hydrolysis of sucrose to glucose and fructose (Hu et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) and sucrose phosphate synthase (SPS) is linked to the regulation of the carbon partition between sucrose and starch in the leaves (Huber and Huber 1996). The activity of these enzymes is dependent on K nutrition (Hafeez et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Hu et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Therefore, K regulates photoassimilation and translocation simultaneously with the enzyme activities (Zahoor et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). When K deficiency occurs during fiber elongation, the decrease in turgor pressure results in shorter fibers (Rosolem and Bogiani \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). As this nutrient is associated with sugar transport in the plant, it is likely that K deficiency may affect the deposition of cellulose microfibrils on the secondary wall in cotton fibers, thus decreasing fiber resistance and micronaire.\u003c/p\u003e \u003cp\u003eSandy soils show low natural fertility, water retention, and cation exchange capacity (CEC) due to the low levels of organic matter and clay, and are prone to K leaching. Potassium chloride, the main source of K for agriculture, was shown to have high mobility in the soil profile, mainly in sandy soils with low CEC (Werle et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) because K adsorption to soil colloids is low (Duiker and Bleeg 2006). Since drainage is fast in sandy soils, K percolation in the soil profile below the rooting zone can impair fertilizer use efficiency during the rainy season (Rosolem et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). To avoid K loss, it has been traditionally recommended to split rates above 50 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of K\u003csub\u003e2\u003c/sub\u003eO (Foloni and Rosolem \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Bernardi et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Antoher strategy suggested to improve fertilizer use efficiency in sandy soils is applying fertilizer to cover crops such as grasses of the genera \u003cem\u003eUrochloa\u003c/em\u003e grown before cotton, because the K taken up returns to the soil mimicking a slow-release fertilizer (Echer et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Therefore, we hypothesize that the application of K to the cover crop grown before cotton is as efficient as that applied during the growing crop in the physiological aspects and in the efficient use of fertilizer.\u003c/p\u003e \u003cp\u003eThe application of K to ruzigrass grown as a cover crop before cotton has been shown to be a valid tool to enhance K use efficiency in the system. Now, we hypothetised that this modification in the managemnet of K fertilization in cotton has no effect on enzimatic activity and cotton fiber cellulose content compared to K applied to cotton. The aim of this work was to assess the leaf area index, enzymatic activity of sucrose metabolism related enzymes and cellulose content in two cotton cultivars under different K fertilizer managements and how the use of ruzigrass as a cover crop would interfere in these processes.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eCultivars had no significant effect on LAI; hence, the results in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e are averaged over cultivars FM 913GLT and FM 983GLT. In the first season, at 60 DAE LAI was higher when K was applied to cotton without ruzigrass, just to ruzigrass or split into ruzigrass and cotton as compared with the other tratments (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). In the second year, there was no difference between treatments at 30 DAE, but at 60 and 90 DAE K fertilization in cotton without ruzigrass LAI was higher, and lower in the presence of ruzigrass without K (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). At 120 DAE, a reduction in LAI was observed in the treatment where there was no K and ruzigrass, and it was lower when K was applied to ruzigrass.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSAI activity in cotton leaves was higher when K fertilization was applied on ruzigrass\u0026thinsp;+\u0026thinsp;cotton (58K on RZ\u0026thinsp;+\u0026thinsp;58 K on C) and when it was performed fully on cotton without ruzigrass on early cultivar (FM 913GLT) but for the late cultivar (FM 983GLT), SAI activity was increased only by K fertilization on cotton without ruzigrass (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003ea FM 913GLT). In both cultivars, the lowest SAI activity was observed in the absence of K and ruzigrass. Early cultivar FM 913GLT had higher SAI activity when K was split in ruzigrass and cotton, but the full K application on cotton without ruzigrass resulted in higher SAI activity in the late cultivar (FM 983GLT).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe greatest SPS activity was found where K fertilization was applied entirely on cotton and it was slightly higher in the presence of ruzigrass for the late cultivar. The lowest activity was observed in the absence of K and in ruzigrass (0K\u0026thinsp;+\u0026thinsp;RZ) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). SPS activity in the early cultivar was improved by K fertilization on cotton after ruzigrass (116K\u0026thinsp;+\u0026thinsp;RZ). Furthermore, the early cultivar FM 913GLT showed greater SPS activity in most K managements. For the late cultivar (FM 983GLT), full K fertilization with (116K\u0026thinsp;+\u0026thinsp;RZ) or without ruzigrass (116K) resulted in higher SPS activity.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe highest SuSy activity in both cultivars was found when K was applied to cotton in the absence of ruzigrass (116K) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003ec), while the lowest was observed in the absence of K fertilization and ruziziensis (0K). Also, late cultivar FM 983GLT had higher SuSy activity in most treatments, but the early cultivar showed higher SuSy activity when receiving K in the absence of ruzigrass (116K). In both cultivars, when K was applied on ruzigrass and cotton, Susy activity increased.\u003c/p\u003e \u003cp\u003eSplitting K fertilitazion half on ruzigrass and half on cotton increased the cellulose content in the cotton fiber 24 DAA. It is interesting that even applying 116 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of K to cotton in the absence of ruzigrass, the fiber cellulose content was similar to those in the absecence of K (Fig.\u0026nbsp;5a). At 48 DAE, when the cellulose contents were higher for both cultivars, there was no difference in cellulose content between treatments (Fig.\u0026nbsp;5b). However, the early cultivar (FM 913GLT) accumulated more cellulose in the fiber at 24 DAA than FM 983 GLT.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003ePotassium management did not affect LAI early in the cycle in both seasons (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e), probably because cotton canopy growth is slow at this stage, as the plant invests most of the carbohydrates to develop its root system (Echer et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). However, at 60 and 90 DAE in the first season and 60, 90 and 120 DAE in the second season, LAI was higher when the plant was fertilized with K, as a result of the increased leaf area and life span, as the leaf's life is reduced by K deficiency (Wrigth 1999).\u003c/p\u003e \u003cp\u003eSAI catalyzes the hydrolysis of sucrose into glucose and fructose (Winter Huber 2000); SPS is directly related to sucrose synthesis from carbon fixed by photosynthesis (Mendicino \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1960\u003c/span\u003e), and SuSy's main function is to cleave sucrose for starch synthesis and cell wall construction (D\u0026eacute;jardin et al. 1997; Nakai et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e1999\u003c/span\u003e). Our results show that potassium fertilization was essential to keep the activities of enzymes involved in carbohydrate metabolism (SAI, SPS and SuSy) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e). In addition, the increase in the activity of these enzymes is potentially linked to K leaf concentration (Hu et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Zahoor et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Tung et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e, Ali et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Studies have reported changes in the leaf sucrose or starch contents and increased enzyme activity and carbohydrate metabolism by K application in cotton (Wang et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Hu et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Zahoor et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Ali et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThere is a strong relationship between cell elongation and leaf K concentration, since the hormones that stimulate cell elongation are highly dependent on adequate levels of K in plant tissues (Cakmak \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). The qualitative characteristics of cotton fibers are positively influenced by an adequate supply of K, as this nutrient regulates the crop cycle, maintains the leaf area, and provides greater cellulose deposition on the inner walls of the fibers improving micronaire index (Carvalho et al. 2006; Hafeez et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Indeed, during the fiber-thickening process, SAI, SPS and SuSy serve as the main enzymes for cellulose synthesis, and their activities are highly dependent upon K application rate (Zahoor et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Tung et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Ali et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), corroborating our results and showing that K application in cotton resulted in increased enzymatic activity concomitantly with the increase in cellulose deposition in the fibers (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e and 5).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003ePotassium fertilization improves physiological parameters such as LAI in a year with a regular rainfall distribution. The absence of K impairs activity of the enzymes SAI, SPS and SuSy, but the effect is cultivar dependent. Early cellulose accumulation in the fiber is favored when cotton is grown after ruzigrass.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eField experiments were conducted in the 2016/17 and 2017/18 cropping seasons in Presidente Bernardes, S\u0026atilde;o Paulo, Brazil, 22\u0026ordm;07'32\" S and 51\u0026ordm;23'20\" W, 475 m asl. The soil is a typic Rhodustult, sandy loam (USDA 2010). The climate is tropical with dry winters and wet, hot summers. Soil samples were taken at the depths of 0 to 20 cm and 20 to 40 cm on May 05, 2016, for chemical analysis as in Raij et al. (2001). Selected chemical and particle size distribution of the soil are in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Lime (45% of CaO and 4.9% of MgO) was broadcast on the soil surface at 1,400 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in September 2016 and 2,000 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in October 2017. Rainfall, maximum and minimum temperatures, and vapor pressure deficit during the experiment are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" 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\u003eSelected chemical properties and particle size distribution of the soil\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"12\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003edepth\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003epH\u003c/p\u003e \u003cp\u003e(CaCl\u003csub\u003e2\u003c/sub\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSOM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003cp\u003e(Resin)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAl\u003csup\u003e3+\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eH\u0026thinsp;+\u0026thinsp;Al\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eK\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eCa\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eMg\u003csup\u003e2+\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eCEC\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ecm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eg dm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003emg dm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c12\" namest=\"c7\"\u003e \u003cp\u003emmol\u003csub\u003ec\u003c/sub\u003e dm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u0026ndash;20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e17.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e7.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e5.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e30.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u0026ndash;40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e18.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e6.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e30.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eZn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003em\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eBS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003esand\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eSilt\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eclay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c6\" namest=\"c2\"\u003e \u003cp\u003e------------------mg dm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e-------------------\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003e---%---\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c11\" namest=\"c9\"\u003e \u003cp\u003e--------g kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e---------\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u0026ndash;20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e42.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e848\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e116\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u0026ndash;40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e31.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e16.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e38.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e841\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e137\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe treatments were an early (FM 913GLT) and a late (FM 983GLT) cotton cultivar and six K fertilization schemes (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Treatments were repeated in the same plots in both seasons. The experimental design was a 2 x 6 factorial in complete randomized blocks with five replicates. Each plot had four 7.0-m cotton rows spaced 0.8 m from each other. The two outer rows and 1.0 at the end of each row were considered borders and not included in evaluations.\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\u003eScheme of cotton K fertilization\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \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\u003eRuzigrass (RZ)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eK rate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTime of K fertilization\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e116K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e116 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e58 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003eapplied 30 DAE and 58 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 45 DAE\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0K\u0026thinsp;+\u0026thinsp;RZ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e116K on RZ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e116 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eapplied on RZ vegetative stage (90 DAE)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e58K on RZ\u0026thinsp;+\u0026thinsp;58K on C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e116 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e58 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003eapplied on RZ vegetative stage and 58 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e on cotton 30 DAE\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e116K on C\u0026thinsp;+\u0026thinsp;RZ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e116 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e58 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e 30 DAE and 58 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e 45 DAE\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eDAE: days after emergence\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \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\u003eEigenvalues of all variables analyzed of FM 913GLT and FM 983GLT under different K management and the use of ruzigrass\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal variance explained (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFM 913GLT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFM 983GLT\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLAI 30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;\u0026thinsp;0.6417\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.0285\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLAI 60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.4406\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.3578\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLAI 90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.8885\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.7625\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLAI 120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.9217\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.7661\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGs F1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.4848\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.0170\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGs F7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.0224\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.5170\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGs C2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.6766\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.2506\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSAI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.7899\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.8911\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSPS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.8047\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.6714\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSUSY\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.7150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.8713\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCellulose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.6132\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-0.5821\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\u003eRuzigrass was sown on May 05, 2016, and June 06, 2017 using 14 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e pure viable seeds. Potassium fertilizer was applied to the grass in the corresponding treatments early September each year, using potassium chloride. Ruzigrass was desiccated on November 1, 2016 and November 6, 2017, using glyphosate (1.92 g ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e a.i.). Ruzigrass averaged 5.6 Mg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of dry biomass. Cotton was sown on December 9, 2016, and November 23, 2017. Phosphorus was applied at 56 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and N at 30 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e as mono ammonium phosphate at cotton planting. The rate of 140 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of N was side dressed and equally split 35 and 45 days after plant emergence (DAE), using ammonium sulphate and urea, respectively. Boric acid was sprayed at 2.0 kg ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e split into 4 weekly applications from the first flower. Weed, pests, and diseases were controlled according to standard farm practices in S\u0026atilde;o Paulo State. Seven days before harvest plants were defoliated with Tidiazurom (60 g ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e a.i.)\u0026thinsp;+\u0026thinsp;Diuron (30 g ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e a.i). Cotton was handpicked 141 and 132 DAE in 2016/17 and 2017/18, respectively.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eLeaf area index 1st and 2nd season\u003c/h2\u003e \u003cp\u003eLeaf area index was measured at 30, 60, 90, and 120 days after emergence using a ceptometer (Accupar LP-80 \u0026ndash; Decagon Devices) in three sub-samples per plot in both seasons.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eEnzyme extraction and assay \u0026ndash; 2nd season\u003c/h2\u003e \u003cp\u003eAt mid flowering (F6/F7 stage \u0026ndash; Marur and Ruano \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2001\u003c/span\u003e), twelve plants per plot had their first position flowers tagged, and 24 days later (24 DAA \u0026ndash; days after anthesis) four bolls and their leaves were collected. At 48 DAA only bolls were collected since leaves were absent. This material was ground to a fine powder in liquid nitrogen. Leaf samples (0.5 fresh weight) and 3.5 mL of extraction buffer (50 mM Hepes-KOH, pH 7.5, 10 mM MgCl\u003csub\u003e2\u003c/sub\u003e, 2 mM EDTA, 5 mM DTT, 2% (w/v) PVP) were ground into a homogenate in an ice bath (Grof et al. 2007). The samples were centrifuged subsequently at 12,000 \u003cem\u003exg\u003c/em\u003e for 20 minutes at 4 \u0026ordm;C. The supernatant was gradually added with Dowex 1x4 and then centrifuged at 12,000 \u003cem\u003exg\u003c/em\u003e for 10 minutes at 4 \u0026ordm;C. The supernatant was collected and the Sucrose Phosphate Synthase (SPS - \u003cem\u003eEC 2.4.1.14\u003c/em\u003e), Sucrose Synthase (SuSy - \u003cem\u003eEC 2.4.1.13\u003c/em\u003e) and Soluble Acid Invertase (SAI - \u003cem\u003eEC 3.2.7.26\u003c/em\u003e) were analyzed. All procedures were done at 4 \u0026ordm;C. Protein measurement was performed as in Bradford (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1976\u003c/span\u003e), using bovine serum albumin as standard.\u003c/p\u003e \u003cp\u003eSPS activity was determined as in Huber and Huber (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1991\u003c/span\u003e). A 50 \u0026micro;L enzyme solution alicote was added to 50 \u0026micro;L solution contained (100 mM Hepes-NaOH buffer, 50 mM MgCl\u003csub\u003e2\u003c/sub\u003e, 20 mM UDPG, 5 mM fructose 6-phosphate, and 17.5 mM glucose 6-phosphate. The reaction was started by the addition of extract and incubated at 25\u0026deg;C for 10 min. After stopping the reaction with 100 \u0026micro;L of 5 M KOH and 10 min of heating at 100\u0026deg;C, followed by 1 mL of 0.14% (w/v) anthrone in 80% (v/v) H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e, was added before 40 min of incubation at 40\u0026deg;C (King et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). SUC-6-P (and SUC) content was determined by comparing the A\u003csub\u003e628\u003c/sub\u003e to that of a standard curve (0-200 nmol of SUC).\u003c/p\u003e \u003cp\u003eSuSy activity (synthetic direction) was determined by replacing fructose 6-phosphate with fructose in the same way as SPS activity. The unit of enzyme activity was expressed as \u0026micro;mol \u0026micro;mol Suc min\u003csup\u003e\u0026ndash;1\u003c/sup\u003e mg\u003csup\u003e\u0026ndash;1\u003c/sup\u003e prot. The SAI activity was determined as in King et al (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). Shortly, 0.2 mL enzyme solution was added into 0.8 mL reaction solution (pH 4.8 0.1M Na2HPO4\u0026ndash;0.1 M sodium citrate, 0.1 M sucrose), and reacted at 37\u0026deg;C for 30min.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eDetermination of cellulose in cotton fiber \u0026ndash; 2nd season\u003c/h2\u003e \u003cp\u003eFruit samples were taken from the first position (P1) of the 10th sympodial branch 24 and 48 DAA and dried in a forced-air oven at 65 \u0026ordm;C for 96 hours. Determinations were conducted in three replications, according to Van Soest et al. (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e1991\u003c/span\u003e). The acid-detergent fiber (ADF) content was determined using an acid detergent (trimethylammonium bromide, standardized sulfuric acid. After examining the ADF content, the cellulose content was assayed in cotton samples using a standardized solution of sulfuric acid.\u003cspan type=\"BoldItalic\" class=\"BoldItalic\" name=\"Emphasis\"\u003eStatistical analysis\u003c/span\u003e\u003c/p\u003e \u003cp\u003eAfter testing for homogeneity and normality, data were submitted to ANOVA. The experiment was arranged in a complete randomized block design in a 2 x 6 factorial scheme (cultivars x K management) and five replicates. The data were analyzed with three-way (cultivar, K management and year) analysis of variance and Tukey test (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) was used to compare treatment means. When the differences between cultivars were not significant, their averages were presented and discussed.\u003c/p\u003e \u003cp\u003eMultivariate analysis was performed via principal component analysis (PCA) to verify the grouping of the different responses to K fertilizer management and the use of ruzigrass in the second year (2017/2018). Considering that the measurement units differed between variables, the data were log-transformed to reduce the effect of the numeric scale (McGarigal et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). The ordination graphic (with two major components) was demarcated by two axes designated as the first (PC1) and second (PC2) principal components.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEthics approval and consent to participate\u003c/em\u003e\u003c/strong\u003e\u003cem\u003e: Not applicable\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/strong\u003e\u003cem\u003e: Not applicable\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/strong\u003e\u003cem\u003e: Not applicable\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCompeting interests:\u003c/em\u003e\u003c/strong\u003e The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFunding:\u003c/em\u003e\u003c/strong\u003e Foundation for Research Support of the State of São Paulo (FAPESP) (grant 2016/16736-4). Funda\u0026ccedil;\u0026atilde;o Agrisus (grant PA 1918/16) and by APPA (S\u0026atilde;o Paulo Cotton Grower\u0026acute;s Association).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthors\u0026apos; contributions:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eFRE methodology, writing original draft, formal analysis, data curation, visualization and supervision. VJSP, GOCB, and GRAS methodology, writing original draft, formal analysis, data curation. ALM writing original draft. PHG writing original draft, formal analysis. CAR writing original draft, formal analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAcknowledgements:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eThe authors thank the Foundation for Research Support of the State of São Paulo (FAPESP) for their support through a Master\u0026acute;s scholarship granted to Peres, V.J.S. (grant 2016/16736-4). This work was partially funded by Funda\u0026ccedil;\u0026atilde;o Agrisus (grant PA 1918/16) and by APPA (S\u0026atilde;o Paulo Cotton Grower\u0026acute;s Association).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAmorim JSL. Correla\u0026ccedil;\u0026atilde;o de Pot\u0026aacute;ssio Mehlich-1 com Pot\u0026aacute;ssio da solu\u0026ccedil;\u0026atilde;o de solos sob diferentes n\u0026iacute;veis de aduba\u0026ccedil;\u0026atilde;o. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://releia.ifsertao-pe.edu.br/jspui/bitstream/123456789/573/1/JANICLECIA%20SANTOS%20LIMA%20AMORIM.pdf\u003c/span\u003e\u003cspan address=\"https://releia.ifsertao-pe.edu.br/jspui/bitstream/123456789/573/1/JANICLECIA%20SANTOS%20LIMA%20AMORIM.pdf\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2019). Accessed 17 Mar 2022.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAli S, Hafeez A, Ma X, et al. Potassium relative ratio to nitrogen considerably favors carbon metabolism in late-planted cotton at high planting density. Field Crops Res. 2018;223:48\u0026ndash;56. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.fcr.2018.04.005\u003c/span\u003e\u003cspan address=\"10.1016/j.fcr.2018.04.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976;72:248\u0026ndash;54. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0003-2697(76)90527-3\u003c/span\u003e\u003cspan address=\"10.1016/0003-2697(76)90527-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBernardi ACC, de Oliveira J\u0026uacute;nior JP, Leandro WM, et al. Doses e formas de aplica\u0026ccedil;\u0026atilde;o da aduba\u0026ccedil;\u0026atilde;o pot\u0026aacute;ssica na rota\u0026ccedil;\u0026atilde;o soja, milheto e algod\u0026atilde;o em sistema plantio direto. Pesqui Agropecu Trop. 2009;39:158\u0026ndash;67.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCakmak I. The role of potassium in alleviating detrimental effects of abiotic stresses in plants. J Plant Nutr Soil Sci. 2005;168:521\u0026ndash;30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/jpln.200420485\u003c/span\u003e\u003cspan address=\"10.1002/jpln.200420485\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarvalho MCS, Ferreira ACB. Manejo de solos aptos \u0026agrave; cotonicultura no cerrado. In: Freire EC, editor. Algod\u0026atilde;o no cerrado do Brasil. 2. ed.: Aparecida de Goi\u0026acirc;nia: Associa\u0026ccedil;\u0026atilde;o Brasileira dos Produtores de Algod\u0026atilde;o; 2007. pp.\u0026nbsp;193\u0026ndash;224.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCassman KG, Kerby TA, Roberts BA, et al. Potassium nutrition effects on lint yield and fiber quality of Acala cotton. Crop Sci. 1990;30:672\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2135/cropsci1990.0011183X003000030039x\u003c/span\u003e\u003cspan address=\"10.2135/cropsci1990.0011183X003000030039x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClement-Bailey J, Gwathmey CO. Potassium effects on partitioning, yield, and earliness of contrasting cotton cultivars. Agron J. 2007;99:1130\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2134/agronj2006.0288\u003c/span\u003e\u003cspan address=\"10.2134/agronj2006.0288\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCopeland L. (1990) Enzymes of sucrose metabolism. In: Lea, PJ, editor. Methods in Plant Biochemistry. 1990. p.\u0026nbsp;73\u0026ndash;85. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/B978-0-12-461013-2.50011-3\u003c/span\u003e\u003cspan address=\"10.1016/B978-0-12-461013-2.50011-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDana S, Herdean A, Lundin B, et al. Retracted: Each of the chloroplast potassium efflux antiporters affects photosynthesis and growth of fully developed Arabidopsis rosettes under short-day photoperiod. Physiol Plant. 2016;158:483\u0026ndash;91. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/ppl.12452\u003c/span\u003e\u003cspan address=\"10.1111/ppl.12452\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDejardin A, Rochat C, Wuill\u0026egrave;me S, et al. Contribution of sucrose synthase, ADP-glucose pyrophosphorylase and starch synthase to starch synthesis in developing pea seeds. Plant Cell Environ. 1997;20:1421\u0026ndash;30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1046/j.1365-3040.1997.d01-32.x\u003c/span\u003e\u003cspan address=\"10.1046/j.1365-3040.1997.d01-32.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuiker SW, Beegle DB. Soil fertility distributions in long-term no-till, chisel/disk and moldboard plow/disk systems. Soil Till Res. 2006;88:30\u0026ndash;41. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.still.2005.04.004\u003c/span\u003e\u003cspan address=\"10.1016/j.still.2005.04.004\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEcher FR, Peres VJS, Rosolem CA. Potassium application to the cover crop prior to cotton planting as a fertilization strategy in sandy soils. Sci Rep. 2020;10:20404. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41598-020-77354-x\u003c/span\u003e\u003cspan address=\"10.1038/s41598-020-77354-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEcher FR, Zanfolin PRL, Moreira ACM, et al. Root growth and carbohydrate partitioning in cotton subjected to shading in the initial phase. Cienc Rural. 2019;49:e20180749. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1590/0103-8478cr20180749\u003c/span\u003e\u003cspan address=\"10.1590/0103-8478cr20180749\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFurlani E Jr, Silva NM, Buzetti S, et al. Extra\u0026ccedil;\u0026atilde;o de macronutrientes e ac\u0026uacute;mulo de massa seca de algod\u0026atilde;o cv. IAC 22. Cult Agron. 2001;10:71\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFoloni JSS, Rosolem CA. Produtividade e ac\u0026uacute;mulo de pot\u0026aacute;ssio na soja em fun\u0026ccedil;\u0026atilde;o da antecipa\u0026ccedil;\u0026atilde;o da aduba\u0026ccedil;\u0026atilde;o pot\u0026aacute;ssica no sistema plantio direto. Rev Bras Cienc Solo. 2008;32:1549\u0026ndash;61. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1590/S0100-06832008000400019\u003c/span\u003e\u003cspan address=\"10.1590/S0100-06832008000400019\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGerardeaux E, Jordan-Meille L, Constantin J, et al. Changes in plant morphology and dry matter partitioning caused by potassium deficiency in \u003cem\u003eGossypium hirsutum\u003c/em\u003e L. Environ Exp Bot. 2010;67:451\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envexpbot.2009.09.008\u003c/span\u003e\u003cspan address=\"10.1016/j.envexpbot.2009.09.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGormus O, El-Sabagh A, Islam MS. Optimizing yield and fiber quality of cotton under Mediterranean environment: managing nitrogen and potassium nutrition. J Exp Biol Agric Sci. 2016; 4:572\u0026ndash;580. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.18006/2016.4(5\u003c/span\u003e\u003cspan address=\"10.18006/2016.4(5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003eS).572.580Grof CP, Albertson PL, Bursle J, et al. Sucrose-phosphate synthase, a biochemical marker of high sucrose accumulation in sugarcane. Crop Sci. 2007; 47:1530\u0026ndash;1539. https://doi.org/10.2135/cropsci2006.12.0825.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHafeez A, Ali S, Ma X, et al. Sucrose metabolism in cotton subtending leaves influenced by potassium-to-nitrogen ratios. Nutr Cycl Agroecosyst. 2019;113:201\u0026ndash;16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10705-019-09976-1\u003c/span\u003e\u003cspan address=\"10.1007/s10705-019-09976-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHu W, Yang J, Meng Y, et al. Potassium application affects carbohydrate metabolism in the leaf subtending the cotton (\u003cem\u003eGossypium hirsutum\u003c/em\u003e L.) boll and its relationship with boll biomass. Field Crops Res. 2015;179:120\u0026ndash;31. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.fcr.2015.04.017\u003c/span\u003e\u003cspan address=\"10.1016/j.fcr.2015.04.017\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHu W, Coomer TD, Loka DA, et al. Potassium deficiency affects the carbon-nitrogen balance in cotton leaves. Plant Physiol Biochem. 2017;115:408\u0026ndash;17. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.plaphy.2017.04.005\u003c/span\u003e\u003cspan address=\"10.1016/j.plaphy.2017.04.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHu W, Loka DA, Fitzsimons TR, et al. Potassium deficiency limits reproductive success by altering carbohydrate and protein balances in cotton (\u003cem\u003eGossypium hirsutum\u003c/em\u003e L.). Environ Exp Bot. 2018;145:87\u0026ndash;94. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envexpbot.2017.10.024\u003c/span\u003e\u003cspan address=\"10.1016/j.envexpbot.2017.10.024\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuber SC, Huber JL. Regulation of maize leaf sucrosephosphate synthase by protein phosphorylation. Plant Cell Physiol. 1991;32:319\u0026ndash;26. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/oxfordjournals.pcp.a078083\u003c/span\u003e\u003cspan address=\"10.1093/oxfordjournals.pcp.a078083\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKahrizi D, Cheghamirza K, Kakaei M, et al. Heritability and genetic gain of some morphophysiological variables of durum wheat (\u003cem\u003eTriticum turgidum\u003c/em\u003e var. \u003cem\u003edurum\u003c/em\u003e). Afr J Biotechnol. 2010;9:4469\u0026ndash;687.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKing SP, Lunn JE, Furbank RT. Carbohydrate content and enzyme metabolism in developing canola siliques. Plant Physiol. 1997;114:153\u0026ndash;60. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1104/pp.114.1.153\u003c/span\u003e\u003cspan address=\"10.1104/pp.114.1.153\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLanger K, Levchenko V, Fromm J, et al. The poplar K\u003csup\u003e+\u003c/sup\u003e channel KPT1 is associated with K\u003csup\u003e+\u003c/sup\u003e uptake during stomatal opening and bud development. Plant J. 2004;37:828\u0026ndash;38. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.0960-7412.2003.02008.x\u003c/span\u003e\u003cspan address=\"10.1111/j.0960-7412.2003.02008.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLima JJ, B\u0026eacute;lot JS. A fibra de algod\u0026atilde;o: qualidade e classifica\u0026ccedil;\u0026atilde;o. In: B\u0026eacute;lot JS, Vilela PMCA, editors. Manual de boas pr\u0026aacute;ticas de manejo do algodoeiro em Mato Grosso. Cuiab\u0026aacute;: Instituto Matogrossense do Algod\u0026atilde;o; 2020. pp.\u0026nbsp;382\u0026ndash;99.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcGarigal K, Stafford S, Cushman S. Multivariate Statistics for Wildlife Ecology Research. New York: Springer; 2000. p.\u0026nbsp;283. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/978-1-4612-1288-1\u003c/span\u003e\u003cspan address=\"10.1007/978-1-4612-1288-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMarur CJ, Ruano O. A reference system for determination of developmental stages of upland cotton. Revis Bras Oleag Fibr. 2001;5:313\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMendicino J. Sucrose phosphate synthesis in wheat germ and green leaves. J Biol Chem. 1960;235:3347\u0026ndash;52. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0021-9258(18)64469-2\u003c/span\u003e\u003cspan address=\"10.1016/S0021-9258(18)64469-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakai T, Tonouchi N, Konishi T, et al. Enhancement of cellulose production by expression of sucrose snthase in \u003cem\u003eAcetobacter xylinum\u003c/em\u003e. Proc Natl Acad Sci. 1999;96:14\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1073/pnas.96.1.14\u003c/span\u003e\u003cspan address=\"10.1073/pnas.96.1.14\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOosterhuis DM, Loka DA, Raper TB. Potassium and stress alleviation: physiological functions and management of cotton. J Plant Nutr Soil Sci 2013; 176:331\u0026ndash;43. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/jpln.20120 0414\u003c/span\u003e\u003cspan address=\"10.1002/jpln.20120 0414\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParveen, Anwar-Ul-Haq M, Aziz T, et al. Potassium induces carbohydrates accumulation by enhancing morpho-physiological and biochemical attributes in soybean under salinity. Arch Agron Soil Sci. 2020;67:946\u0026ndash;59. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/03650340.2020.1769075\u003c/span\u003e\u003cspan address=\"10.1080/03650340.2020.1769075\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePereira JRA, Rossi P Jr. Manual Pr\u0026aacute;tico de Avalia\u0026ccedil;\u0026atilde;o Nutricional de Alimentos. Piracicaba: FEALQ; 1995. 34p.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePettigrew WT, Heitholt JJ, Meredith WR Jr. Genotypic interactions with potassium and nitrogen in cotton of varied maturity. Agron J. 1996;88:89\u0026ndash;93. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2134/agronj1996.00021962008800010019x\u003c/span\u003e\u003cspan address=\"10.2134/agronj1996.00021962008800010019x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRaphael JPA, Rosolem CA, Echer FR. Distribui\u0026ccedil;\u0026atilde;o da produ\u0026ccedil;\u0026atilde;o no algodoeiro: conceitos, fatores ecofisiol\u0026oacute;gicos, e implica\u0026ccedil;\u0026otilde;es sobre a produtividade e sobre a qualidade da fibra. In: B\u0026eacute;lot JS, Vilela PMCA, editors. Manual de boas pr\u0026aacute;ticas do algodoeiro em Mato Grosso. Cuiab\u0026aacute;: Instituto Matogrossense do Algod\u0026atilde;o; 2020. pp.\u0026nbsp;112\u0026ndash;34.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRaij. Bvan.An\u0026aacute;lise qu\u0026iacute;mica para avalia\u0026ccedil;\u0026atilde;o da fertilidade de solos tropicais. Campinas. Instituto Agron\u0026ocirc;mico de Campinas; 2001. 285p.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosolem CA, Bogiani JC. Nutri\u0026ccedil;\u0026atilde;o e estresses nutricionais em algodoeiro. In: Echer FR, editor. O algodoeiro e os estresses abi\u0026oacute;ticos: temperatura, luz, \u0026aacute;gua e nutrientes. Cuiab\u0026aacute;: Instituto Matogrossense do Algod\u0026atilde;o; 2014. pp.\u0026nbsp;103\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosolem CA, Mikkelsen DS. Potassium absorption ans partitioning in cotton as affected by periods of potassium deficiency. J Plant Nutr. 1991;14:1001\u0026ndash;16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/01904169109364259\u003c/span\u003e\u003cspan address=\"10.1080/01904169109364259\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosolem CA, Echer FR, Lisboa IP, et al. Ac\u0026uacute;mulo de Nitrog\u0026ecirc;nio, f\u0026oacute;sforo e pot\u0026aacute;ssio pelo Algodoeiro Sob Irriga\u0026ccedil;\u0026atilde;o Cultivado em Sistemas Convencional e Adensado. Rev Bras Cienc Solo. 2012;36:427\u0026ndash;66. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1590/S0100-06832012000200015\u003c/span\u003e\u003cspan address=\"10.1590/S0100-06832012000200015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosolem CA, Almeida DS, Rocha KF, et al. Potassium fertilization with humic acid coated KCl in a sandy clay loam tropical soil. Soil Res. 2017;56:244\u0026ndash;51. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1071/SR17214\u003c/span\u003e\u003cspan address=\"10.1071/SR17214\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosolem CA, Santos FPD, Foloni JSS, et al. Pot\u0026aacute;ssio no solo em conseq\u0026uuml;\u0026ecirc;ncia da aduba\u0026ccedil;\u0026atilde;o sobre a palha de milheto e chuva simulada. Pesq Agropec Bras. 2006;41:1033\u0026ndash;40. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1590/S0100-204X2006000600020\u003c/span\u003e\u003cspan address=\"10.1590/S0100-204X2006000600020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaparov A, Eleshev R, Suleimenov B, et al. Effect of potassium chloride application for rice, cotton and potato in the irrigated zone of Kazakhstan. Better Crops Plant Food. 2013;97:23\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShabala L, Zhang J, Pottosin I, et al. Cell-type specific H\u003csup\u003e+\u003c/sup\u003e-ATPase activity in root tissues enables K\u003csup\u003e+\u003c/sup\u003e retention and mediates acclimation of barley (\u003cem\u003eHordeum vulgare\u003c/em\u003e L.) to salinity stress. Plant Physiol. 2016;172:2445\u0026ndash;58. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1104/pp.16.01347\u003c/span\u003e\u003cspan address=\"10.1104/pp.16.01347\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShabala S. Signalling by potassium: another second messenger to add to the list? J Exp Bot. 2017;68:4003\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/jxb/erx238\u003c/span\u003e\u003cspan address=\"10.1093/jxb/erx238\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSilva NM, Carvalho LH, Cia E, et al. Seja doutor do seu algodoeiro. Informa\u0026ccedil;\u0026otilde;es Agron\u0026ocirc;micas, Piracicaba, 1995, n. 69, mar. (Encarte, Arquivo do Agr\u0026ocirc;nomo n. 8).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTung SA, Huang Y, Ali S, et al. Mepiquat chloride application does not favor leaf photosynthesis and carbohydrate metabolism as well as lint yield in late-planted cotton at high plant density. Field Crops Res. 2018;221:108\u0026ndash;18. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.fcr.2018.02.027\u003c/span\u003e\u003cspan address=\"10.1016/j.fcr.2018.02.027\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVan Soest PV, Robertson JB, Lewis BA. Methods for Dietary Fiber, Neutral Detergent Fiber, and Nonstarch Polysaccharides in Relation to Animal Nutrition. J Dairy Sci. 1991;74:3583\u0026ndash;97. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3168/jds.S0022-0302(91)78551-2\u003c/span\u003e\u003cspan address=\"10.3168/jds.S0022-0302(91)78551-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang N, Hua H, Eneji AE, et al. Genotypic variations in photosynthetic and physiological adjustment to potassium deficiency in cotton (\u003cem\u003eGossypium hirsutum\u003c/em\u003e). J Photochem Photobiol B: Biol. 2012;110:1\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jphotobiol.2012.02.002\u003c/span\u003e\u003cspan address=\"10.1016/j.jphotobiol.2012.02.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang Y, Wu WH. Regulation of potassium transport and signaling in plants. Curr Opin Plant Biol. 2017;39:123\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.pbi.2017.06.006\u003c/span\u003e\u003cspan address=\"10.1016/j.pbi.2017.06.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWinter H, Huber SC. Regulation of sucrose metabolism in higher plants: localization and regulation of activity of key enzymes. Crit Rev Plant Sci. 2000; 31\u0026ndash;67. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/07352680091139178\u003c/span\u003e\u003cspan address=\"10.1080/07352680091139178\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang G, Tang H, Tong J, et al. Effect of fertilization frequency on cotton yield and biomass accumulation. Field Crops Res. 2012;125:161\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.fcr.2011.08.008\u003c/span\u003e\u003cspan address=\"10.1016/j.fcr.2011.08.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWerle R, Garcia RA, Rosolem CA. Potassium leaching as affected by soil texture and potassium availability. Rev Bras Cienc Solo. 2008;32:2297\u0026ndash;305. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1590/S0100-06832008000600009\u003c/span\u003e\u003cspan address=\"10.1590/S0100-06832008000600009\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao D, Oosterhuis DM, Bednarz CW. Influence of potassium deficiency on photosynthesis, chlorophyll content, and chloroplast ultrastructure of cotton plants. Photosynthetica. 2001;39:103\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1023/A:1012404204910\u003c/span\u003e\u003cspan address=\"10.1023/A:1012404204910\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZahoor R, Dong H, Abid M, et al. Potassium fertilizer improves drought stress alleviation potential in cotton by enhancing photosynthesis and carbohydrate metabolism. Environ Exp Bot. 2017;137:73\u0026ndash;83. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envexpbot.2017.02.002\u003c/span\u003e\u003cspan address=\"10.1016/j.envexpbot.2017.02.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Gossypium hirsutum L., enzyme regulations, leaf area index, stomata conductance","lastPublishedDoi":"10.21203/rs.3.rs-2325912/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2325912/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePotassium (K) is prone to be washed out of plant tissues independent of mineralization since it is not strongly bound to organic structures in the plant. Therefore, cover crops can enhance K cycling in cropping systems increasing the nutrient use efficiency by taking it up deep in the soil profile and releasing it on the soil surface. However, it is not clear if this cycling would have an effect on cotton morphophysiology, enzyme activity, and eventually on fiber quality.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eCotton leaf area index was increased late in the season by K, with small differences between fertilized treatments, but was highest at full bloom when at least part of the K was applied to cotton Consequently, the enzymatic activity and accumulation of cellulose in the cotton fiber were also increased.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003ePotassium fertilization improves cotton physiological parameters such as leaf area index, but the effect on enzyme activity depends on the enzyme and on the cotton cultivar. Early cellulose accumulation in the fiber is favored by potassium fertilization and cotton rotation with ruzigrass.\u003c/p\u003e","manuscriptTitle":"Effects of potassium management on enzyme activity and cotton fiber cellulose content","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-12-21 15:32:32","doi":"10.21203/rs.3.rs-2325912/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b660f75d-44db-45c3-a873-de17e3b8984c","owner":[],"postedDate":"December 21st, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-03-06T08:14:12+00:00","versionOfRecord":[],"versionCreatedAt":"2022-12-21 15:32:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2325912","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2325912","identity":"rs-2325912","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}