Factors Influencing the Development and Accumulation of Heavy Metals in Hop Plants Grown in Tropical Regions

Factors Influencing the Development and Accumulation of Heavy Metals in Hop Plants Grown in Tropical Regions | 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 Article Factors Influencing the Development and Accumulation of Heavy Metals in Hop Plants Grown in Tropical Regions Mariana Ferreira Santa Cruz Coimbra, Ingrid Lobo da Silva Coêlho, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7285459/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 The aim of this study was to evaluate heavy metal contamination in an area of Humulus lupulus L. production, as well as to identify the main factors that help enrich the soil and plants with these elements. The study was conducted in one of the largest hop-producing properties in Brazil, located in a mountain agroecosystem. Samples of soil and plant tissue were collected at 42 points throughout the study area. Soil fertility and particle size were analyzed, in addition to determining the levels of heavy metals in the samples using acid digestion, as per EPA methods 3050 and 3050B. This was followed by atomic absorption spectrometry. The Pollution Index (PI) was then calculated, based on the results. The relationship between the variables was investigated using principal component analysis (PCA) and cluster analysis. Cadmium (Cd) was the only element that showed moderate to severe enrichment in the soil. The terrain, parent material and management practices adopted on the property had a significant influence on the enrichment of metals in both the soil and the plants, as well as impacting hop productivity. These factors were therefore mainly responsible for the transfer and accumulation of metals in the plants. Despite this, the levels of metals detected in hop inflorescences show no risk of being transferred to derivative products, such as beer. environmental monitoring soil quality soil pollution Humulus lupulus L. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Hops are a plant of family Cannabaceae, genus Humulus, species Humulus lupulus L., which has been cultivated for centuries in countries with temperate climates and a marked photoperiod (14-16h), such as Germany and Belgium, where they are harvested annually (Bocquet et al., 2018). It is characterized as a perennial, herbaceous, dioecious, anemophilous and rhizomatous climbing plant, which produces inflorescences that, when mature, are known as cones (Durello et al., 2019). In the basal area of the cones, glands that are responsible for secreting a type of yellowish pollen (called lupulin), synthesize and store volatile compounds, such as essential oils and alpha and beta acids (Almaguer et al., 2014; Durello et al., 2019). These compounds are important raw materials for the brewing industry, affording beer its bitterness, aroma and flavor; while in the pharmaceutical industry, they have a beneficial effect in treating disorders and diseases such as cancer (Jiang et al., 2018; Alonso-Esteban et al., 2019; Spósito et al., 2019). According to the Beer Yearbook 2022, published by the Ministry of Agriculture and Livestock, Brazil is the third largest producer and consumer of beer in the world (Brasil, 2023). However, production of the ingredients needed to make beer remains low, meaning the country is a major importer of these raw materials, especially hops (Dagostin, 2019). Given the demand, it is extremely important to conduct studies that evaluate the adaptation and production of this ingredient to meet the needs of the domestic market. Hop cultivation is relatively new to Brazil, but has already proven viable in several areas, giving two harvests per year in various regions, including the states of Rio Grande do Sul, Santa Catarina, Paraná, São Paulo, Rio de Janeiro, Minas Gerais and the Federal District (Spósito et al., 2019; Aquino et al., 2022). Although the latitudes are not considered ideal for the crop, proper management and the selection of varieties that are adapted to tropical environments mean that such initiatives are relatively successful (Aquino et al., 2022; Durello et al., 2019). According to Aquino et al. (2022), the nutritional requirement of hops is high due to their rapid growth and large size, resulting in the accumulation of significant amounts of shoot biomass. In hop cultivation, N is normally applied at a rate of between 180 and 220 kg ha -1 (Teixeira et al, 2022), depending on the organic matter content of the soil. However, its P requirement is relatively low, estimated at 7.5 to 9 kg P 2 O 5 ha -1 (Gingrich et al., 1994). Another basic macronutrient for hop growth is potassium (K), which helps in adjusting turgor and controlling osmotic pressure, membrane polarization and protein biosynthesis (Chen et al., 2008). The crop demand for K, applied as K 2 O, ranges from 80 to 138 kg ha -1 , and the use of K significantly reduces the occurrence of pests and diseases (Barker and Pilbeam, 2015),. Considerable quantities of nutrients are exported from the soil during the crop cycle through successive cone harvests and pruning of the foliage. It is therefore crucial to replace these nutrients using strategies that favor the productive capacity of the soil (Aquino et al., 2022). However, there is still little information regarding specific management strategies for cultivating hops in tropical regions, particularly in relation to fertilization, and especially under the soil and climate conditions of Brazil (Stein, 2020). Many of these strategies are still in the experimental phase, where doses of mineral and organic fertilizers are tested with a view to increasing cone productivity, thereby reducing dependence on inputs that are generally imported by the beer industry. According to Spósito et al. (2019), almost all knowledge of the crop and management practices are based on research carried out in regions with a temperate climate, similar to that of its place of origin, with little research in regions with a subtropical or tropical climate. As soil fertility is fundamental to hop cultivation, effective crop management requires a combination of strategies to ensure adequate plant nutrition without compromising the quality of the end product (the cone) or the environment, especially regarding the accumulation of potentially toxic elements in the soil and plants (Teixeira et al., 2022).. It is therefore essential to consider not only the amount of fertilizer, but also sustainable methods of ensuring soil fertility. Various studies have demonstrated an increase in the concentration of heavy metals in agricultural areas in the mountainous region of Rio de Janeiro (Franco et al., 2020), and point out that one of the main sources of contaminants in areas of agricultural production is linked to the intensive use of such inputs as synthetic and soluble fertilizers, as well as organic waste, i.e. poultry litter, which include these elements due to impurities from the production process (Sousa et al., 2020; Gonçalves et al., 2022). It should be noted that heavy metals can enter the soil through natural processes (Jia et al., 2018) and the excessive use of chemical products, and can lead to contamination and significant environmental problems (Akter et al., 2023) due to the toxicity and persistence of these elements in the environment (Ali et al., 2019). In view of the above, the aim of this study was to characterize a reference area for Humulus lupulus L. production in Brazil in terms of contamination by heavy metals (Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al) and their transfer to the plants, especially to the cones, as well as identifying the environmental factors that most influence development and production in the crop. 2. Materials and Methods 2.1 Study area Soil and plant samples were collected from a property used for hop production (Fazenda São Francisco Farm) in the district of Teresópolis in the mountainous region of Rio de Janeiro, belonging to the Grupo Petrópolis national beverage company (GP). Four areas were studied (Figure 1) that present different types of relief and cultivar production, and are managed using soluble mineral fertilizers and organic waste (poultry litter). The study area has a history of dairy cattle production, and for many years was covered by pasture, which led to a level of chemical and physical degradation of the soil. However, in 2018, the GP Hop Program was initiated, which currently includes more than 21,000 plants at the Fazenda São Francisco Farm in an area of approximately 5 ha (Freitas, 2022). 2.2 Collecting the samples, with information on the management of each area Single soil samples were collected from 42 points at depths of 0-0.2 m and 0.2-0.4 m, with the plant samples collected at the same locations. It should be noted that some plants had not completed their cycle, making it impossible to collect cones in areas 2 and 3. Nitrogen, phosphate and potassium mineral fertilizers as well as organic fertilizer (poultry litter) were applied to each area considering a spacing between plants of 2 m x 1 m and 3 m x 1 m. In addition, products were periodically applied to control pests and diseases, such as Bordeaux mixture to control mildew, a recurrent disease in the crop. It should be noted that the areas were set up at different times (Table 1). Table 1. Set up, altitude and area of hop-production Areas 1, 2, 3 and 4 in Teresópolis in the mountainous region of Rio de Janeiro. Samples of chemical fertilizer (nitrogen, potassium and phosphate) and organic fertilizer (chicken litter) were also collected in the study area. The samples were dried in a forced air circulation oven at 60°C to constant weight then ground and macerated. After preparation, they were digested and analyzed as per method 3050B of the United States Environmental Protection Agency (US EPA, 1996) to determine the levels of Cd, Cr, Cu, Mn, Ni, Pb and Zn. The extracts were quantified by atomic absorption spectrometry using the Varian SpectrAA 55B (Agilent Technologies) (Table 2). Table 2. Average levels of heavy metals present in the mineral fertilizers and organic manure (chicken litter) used in the study area. 2.3 Preparing and analyzing the soil samples The soil samples were air-dried, crushed, sieved through a 2-mm mesh and homogenized to determine the chemical and physical attributes of the soil. They were then macerated in an agate mortar and sieved through a 0.150-mm mesh to determine the levels of metal bioavailability (F1+F2). The soil samples were analyzed in triplicate for organic carbon (Corg); pH (H 2 0); pH (KCl); exchangeable bases such as calcium (Ca), magnesium (Mg), sodium (Na) and potassium (K); exchangeable aluminum (Al); assimilable phosphorus (P); potential acidity (H+Al); sum of bases (SB); base saturation (V%) and cation exchange capacity (CEC), as per EMBRAPA methodology (Teixeira et al., 2017). The 3050B method proposed by the United States Environmental Protection Agency (US EPA, 1996) was used to determine the pseudo-total metal content (Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al). The extracts were quantified by atomic absorption spectrometry using the Varian SpectrAA 55B (Agilent Technologies). SRM 2709 San Joaquin Soil, certified by the National Institute of Standards and Technology (NIST, USA), was used as the reference to validate the analytical method. The results for recovery of the reference material were within the ranges accepted by NIST as normal for soil samples, with recovery values greater than 95%. 2.4 Preparing the plant samples The collected plants were harvested at the peak of cone maturation, albeit at different times in the four areas under analysis. The plants were cut at the base of the stem and the shoots carefully removed in the field. They were then separated, stored in paper bags and properly identified. The plant material was weighed to determine the fresh weight and then dried in a forced circulation oven at 60°C to constant weight to obtain the dry weight. After weighing, the samples were crushed in an IKA A11 analytical mill and stored in paper bags for later chemical analysis. 2.5 Determining the levels of Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al in the plant material. To determine the total metal and nutrient content of the shoots (leaves and stems) and cones, the prepared samples were weighed in triplicate and then digested using EPA method 3050 (United States Environmental Protection Agency - US EPA, 2008). The resulting extracts were analyzed by atomic absorption spectrometry to determine the metal content. Na and K were analyzed using flame photometry. The quality of the analytical procedures was verified using the SRM 1573a reference material (tomato leaves), certified by the National Institute of Standards and Technology (NIST, 2018). The recovery rates for Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al were considered adequate, with recovery values greater than 90%. 2.6 Pollution Index (PI) The pollution index (PI) was determined to assess the enrichment or depletion of the soil in relation to the presence of metals (Khan et al., 2008). The PI was obtained from the ratio between the current pseudo-total concentration of each metal (Cn) in the soil sample and its respective quality reference value, also known as the geochemical background (PI = Cn/QRV) (USERO et al., 1997), where PI is the pollution index, Cn is the concentration of heavy metal in the soil and QRV is the quality reference value. The reference values used in this study were based on Lima et al. (2018). The PI indicates the degree of metal contamination of the soil, classified as per Wu et al. (2015): a) PI ≤ 1 (not contaminated); b) 1 < PI ≤ 3 (low contamination); c) 3 5 (severe contamination). 2.7 Statistical analysis The statistical analysis included both descriptive and multivariate analysis tools. Descriptive analysis of the metal content of the soil and plants, fresh and dry plant weight, soil attributes, bioaccumulation factor and pollution index was carried out using positional (mean and median) and amplitude parameters (minimum, maximum and standard deviation) in Microsoft ® Office Excel ® . Box plots were generated using the SigmaPlot 12.5 software. The multivariate procedures included cluster analysis and discriminant analysis. For the cluster analysis, the Euclidean distance was used as a measure of similarity, while the Ward hierarchical method was adopted as the clustering algorithm, which minimizes the sum of squares (SQ) within each group, generating more homogeneous groups with each grouping (Hair et al., 2005). For this, the pseudo-total values of the elements Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al were used as grouping variables. The results were standardized to mean 0 and variance + or -1. To interpret and form the groups, a value equal to 1.25 times the standard deviation of the linkage distance of all the observations was adopted as the cut-off point for the dendrogram (Milligan & Cooper, 1985). Validation and the appropriate number of groups were performed by cross-validation in discriminant analysis, using the same discriminating variables used in the grouping, assuming equality of the covariance matrix and an equal likelihood of classification for the groups. Principal component analysis (PCA) using the R software (R Core Team, version 3.4.4) was used to relate the data on soil fertility (P, pH, Ca, Mg, Na, K, H+Al, V, CEC, SB and CO), particle size, elevation, pseudo-total values for Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al in the soil, bioaccumulation factor (BAF) in the shoots (Pa) and cones (Cn), pollution index (PI), and total accumulated levels of Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al, Ca and Mg in the shoots and cones of the plants. 3. Results 3.1 Assessing enrichment of the pollution index When analyzing Figure 2, the median values of the pollution index (PI) for each of the metals under analysis are below 3 (green line) indicating no contamination (PI ≤ 1) or very little contamination (1 < PI <3) at most of the points where the soil samples were collected. However, for Cd, despite most of the samples showing low contamination, there was a wide range of PI values (0 to 41), with some points showing severe contamination (PI > 5), which may represent a risk to the environment and to any plants grown in these areas. Figure 3 shows the percentage of soil samples within each class proposed by Wu et al. (2015) for each metal. For Ni, Co and Cr, 100% of the samples had PI values of less than one. As a result, it is thought that the levels of these elements remaining in the soil after the hop harvest are of lithogenic origin. PI values greater than one were seen for Cd, Cu, Mn, Pb and Zn at certain points, confirming enrichment of these metals in some areas, albeit poor for most of the samples. Therefore, for a better understanding of the factors involved in the dynamics of these metals in the soil and their enrichment in areas of hop production, Principal Component Analysis (PCA) was carried out between the PI for Cd, Cu, Mn, Pb and Zn and the soil attributes (Figure 4). According to the biplot graph obtained with the PCA between the soil attributes and the pollution indices (PI) for the metals (Figure 4), it can be seen that in CP1 (the component that explains 47.65% of the variance in the data), PICd shows a positive relationship with the potential acidity of the soil (H+Al), CEC, pseudo-total levels of Al and Fe, clay content and elevation (Elev), and an inverse relationship with soil pH. CP2 shows a possible, albeit poorer, relationship with COrg, which is related to the CEC. It should be noted that these two components together explain 59.82% of the accumulated variance in the data. Furthermore, there was no relationship between Ca, Mg, K or P and PICd. For Cu, Mn, Pb and Zn, the PI showed a close positive relationship with the Ca, Mg, P and K content, and an inverse relationship with elevation, demonstrating the influence of the soluble fertilizers and correctives used in the area on the enrichment of these metals; as well as the influence of the terrain, which possibly favored soil being dragged from the surface layer, exposing the sub-surface layer and facilitating the transport of these elements from the highest to the lowest point in the landscape. 3.2 Characterization of groups of soil samples from an area of hop-production in the mountainous region of Rio de Janeiro Cluster analysis was carried out to identify groups of samples with a similar metal content in the areas of hop-production, and to determine the characteristics that contribute to the differences. The analysis was based on the pseudo-total levels of Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al. Figure 5 shows the dendrogram obtained from the cluster analysis. To define the number of groups to be adopted, a linkage distance of 0.045 was used as the cut-off point in the dendrogram, this value being 1.25 times the standard deviation of the linkage distance of all the observations (Milligan and Cooper, 1985), and suggests the formation of up to seven groups. To help choose the appropriate number of groups, cross-validation in discriminant analysis (DA) was applied, which indicated the formation of two groups to be the most appropriate, as this had the lowest rate of error (< 0.1 per cent) and made it easier to explain the variability in the samples. The two groups were Group 1 (G1) with 37 observations and Group 2 (G2) with 47 observations, giving a total of 84 soil samples. According to the data shown in Figure 6 and Table 1S, the two groups presented different characteristics in terms of elevation, chemical and physical attributes and pseudo-total content of heavy metals in the soil. Group 1 was characterized by the smallest number of samples (37), and was formed by soil samples located at the lowest point of the landscape, with a sandy loam texture and higher values for sand, silt, pH, P, Ca, Mg, Na and K, organic carbon, and the metals Zn, Pb, Cu and Mn (48.84, 276.08, 15.18 and 17.85 mg kg -1 , respectively), probably due to the greater input of mineral and organic fertilizers in the area, reflecting the effect of the management practices. The average P and K levels in the representative soils of G1 are worth highlighting, as they are up to six and three times greater, respectively, than those found in the soils of G2 (see Table 1S). According to Freire et al. (2013), these levels are classified as 'very high' for P (>30 mg kg-1) and 'high' for K (91–135 mg kg-1), possibly due to the intense application of soluble phosphate and potassium fertilizers in these areas. The areas in G1 had an average pH value in water of 5.69, a value that is very close to 5.5, considered ideal for hop cultivation (Spósito et al., 2019). It should be noted that the average pH values (in water and KCl) in G1 show a negative charge balance, i.e. a negative ∆pH (∆pH = pH KCl 1 mol L-1 – pH in water), indicating a predominance of negative charges in these soils and, therefore, a greater cation exchange capacity, which affords more favorable conditions for plant development, as can be seen in Table 3 and Figure 7b. G2 grouped 47 samples, collected in areas with the highest elevation and the highest clay content (53%), with the soil texture classified as clayey. G2 presented higher values for CEC and the metals Fe, Al, Ni, Co, Cd and Cr compared to the soil samples from G1. This group also exhibited higher levels of organic matter and clay, both of which affect metal retention and the CEC. The lithology of the mountainous region of the state of Rio de Janeiro mostly comprises gneissic (44.4%) and granitic (24.6%) massifs, which give rise to acidic soils, with a diverse mineralogy dominated by clay minerals such as kaolinite, as well as oxides, hydroxides and oxyhydroxides of Fe, Al and Mn (Guimarães, 2020), which may also have favored the lithogenic enrichment of Cr, Co and Ni. Over 50% of the soil samples from G2 exhibited more pronounced acidity (median = 5.17), which may be critical for crop development and possibly reflected in the poor shoot dry matter production (leaves + steams + cones) (Table 3 and Figure 7b). Figure 7 and Tables 3, 2S and 3S show the set of standardized mean values and the descriptive analysis of the bioavailable metal content of the soil, the fresh and dry weight of the aerial part of the plantass, and the number of cones for each group (G1 and G2). In terms of metal bioavailability, figure 7a shows that G1 had the highest levels of Cr, Cu, Mn, Pb and Zn, while G2 had the highest levels of Cd and Ni, which, in general, favored increased accumulation of these elements by the plants. It should be noted that Pb and Ni showed no relationship between the bioavailable soil content and that accumulated in the plants. All the results relating to the fresh and dry weight of aerial part of the plants (Figure 7b) were higher in the representative samples from G1. However, it was not possible to compare the number or fresh and dry weight of the cones, since the plants in G2 did not produce any cones, as shown in Table 3. This may have been due to the limitations of soil and terrain discussed above. Table 3 Mean, median, minimum and maximum values for fresh and dry weight of the aerial part of the plantas (FAPW and DAPW) and cones (FCnW and FCnW), with the number (NCn) of cones for each group formed in the cluster analysis. As shown in Table 3, G1 had the highest values for fresh and dry shoot weight compared to G2. Rodolfi et al. (2021) found very similar values in a study conducted in Italy with the ‘Cascade’ hop cultivar. Based on the levels of each element in the leaves and steams of the plantas (Figure 7c and Table 2S), it can be seen that the samples from G1 exhibited higher average levels of P, Mg, Ca, Zn, Ni, Mn, Fe, Cu, Cr and Al, in the following order: Ca > Mg > K > P > Na > Al > Fe > Mn > Zn > Pb > Cu > Co > N > Cr. However, when analyzing the accumulated content (Figure 7d) of each element in the aerial part of the plant (leaves, steams and cones), only K showed different behavior to that seen with the accumulated elements, since the samples from G1 accumulated more K in the plants than did those from G2. The levels of Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn, Al, Na, P, K, Ca and Mg in the cones (Table 4) showed significant variation, with the following order for the median values: Ca > Mg > P > Fe > Al > Zn > Mn > K > Cu > Pb > Na. Median levels of Ni, Co, Cr and Cd were not detected. Similar values for Cu (6.32 mg kg -1 ) and Cd (0.04 mg kg -1 ) were found by Liu (2019) when evaluating the heavy metal content of hops grown in China. However, the same research showed much higher values for Fe (772.55 mg kg -1 ) and Co (0.64 mg kg -1 ), and lower values for Al (119.06), K (2635) and Ca (1522.67) compared to the accumulated values in the cones from G1. Ni and Cr were detected in less than 20% of the cone samples. Table 4. Mean, median, minimum and maximum values for the nutrient and heavy metal content in the cones from G1. It should be noted that, as per the National Health Surveillance Agency (ANVISA), there are no reference limits for the metal content of hops. However, metal concentrations in hops are insignificant when it comes to metals contaminating beer (Catelli, 2022), possibly due to the low, albeit essential, percentage contribution of hops to beer production (2%). Nevertheless, metal accumulation in the soil and plants should be monitored, since the use of mineral and organic fertilizers favors the accumulation of these elements, which can lead to a loss of environmental quality when cultivating hops. 4. Discussion The average pseudo-total content for Fe (98.37 g kg -1 ) and Al (189.43 g kg -1 ) in G2 were more marked than those in G1 and may be closely linked to the chemical and physical characteristics of the soils in the region, which are predominantly made up of Cambisols, Argisols and Latosols (EMBRAPA, 2017). The relationship of the soil with the parent material is quite evident when the soil is formed in situ, i.e. directly on the parent material (Fadigas, 2002), resulting in more significant levels of Fe, Al, Ni, Co, Cd and Cr in G2, which were probably added to the soil naturally by weathering of the parent material, especially when formed by rocks rich in oxides and silicates (Oliveira et al., 2010). In terms of Cd, Figure 3 shows that approximately 30% of the samples analyzed exhibit contamination ranging from moderate (35) (22.6%), indicating that, in addition to the lithogenic contribution in these areas, there was also an anthropogenic contribution, possibly associated with the type of management and the characteristics of the soil. Sousa et al. (2020) also saw severe Cd enrichment in areas of tomato-production in the mountainous region of Rio de Janeiro. Using principal component analysis (PCA), the authors found that PICd was closely related to the pseudo-total Al and Fe content, the elevation of the area, and, to a lesser extent, the K content. The authors conclude that any Cd remaining after the tomato harvest is predominantly associated with the levels of Fe and Al oxides, hydroxides and oxyhydroxides in the soil, i.e. is lithogenic in nature. However, the high PI values for cadmium may also reflect an anthropogenic contribution, as evidenced by the observed relationship with K, which suggests a possible contribution from potash and organic fertilizers (Sousa et al., 2020). The results show that Cd remaining after the hop harvest is strongly related to the levels of Fe and Al oxides, hydroxides and oxyhydroxides in the clay fraction of the soil. However, the high level of Cd enrichment seen in certain areas reflects not only a lithogenic contribution, but also an anthropogenic contribution possibly linked to the use of organic fertilizers in these areas and to the higher clay and Corg content, which may have favored greater Cd retention. The results indicate a significant effect from the terrain, a result of the transport and accumulation of metals at lower elevations. The greater elevation of the representative areas in G2 has a direct influence on the mobility of fertilizers and soil particles, which are easily washed away in mountainous areas (Franco et al., 2020; Sousa et al., 2020). According to Grisel and Assis (2015), the greater elevation and steeper slopes make it easier for smaller particles, such as clay, to be transported and accumulate in lower areas of the landscape. As a result, the natural fertility of the soil has decreased over the years, leading to an increased dependence on the use of fertilizers to restore the levels of soil fertility. The soils of G2 are therefore greatly influenced by the terrain, which possibly led to the removal of the surface horizons and exposure of the sub-surface horizons, as shown by the higher clay content in these areas. Amaral Sobrinho et al. (1992) suggest the following typical ranges for heavy metals in phosphate fertilizers: 0.1-170 mg kg -1 Cd, 7-225 mg kg -1 Pb, 7-38 mg kg -1 Ni, 1-300 mg kg -1 Cu and 50-1450 mg kg -1 Zn. Similar results were found by Campos et al. (2005), who evaluated the metal content of eight types of soluble phosphate fertilizer, with results that ranged from 4.2 to 115.0 mg kg -1 for Cu, 17.0 to 234.0 mg kg -1 for Pb, and 20.0 to 1013.0 mg kg -1 for Zn. These results demonstrate the potential of phosphate fertilizers, which are widely used in the study area, to increase the levels of these metals in the soil, particularly Cu, Pb and Zn in the soils of G1. Gonçalves et al. (2022) also found excessive use of phosphate fertilizers when analyzing soil samples from areas of kale-production in Petropolis in the mountainous region of Rio de Janeiro, where 70.5% of the samples had very high levels of P (> 30 mg kg -1 ). Very similar dynamics are seen for Mn, which also showed more pronounced values in G1. Mn oxides are generally more soluble than Fe and Al oxides, facilitating their dissolution and transport from higher to lower elevations. These results suggest a condition that favors metal bioavailability in the soil (Kumar et al., 2020a, 2021). The better performance of the plants in G1 is possibly due to the chemical and physical attributes of the soil, as discussed above, and to the different types of management for some of the plants in G1, which are located at a lower elevation and receive a greater supply of organic and mineral inputs. Although these plants were in their first crop cycle, they come from a different genetic seedling bank to the plants in the other areas, which may have reflected in their superior productive performance. The median values for fresh cone weight (0.370 kg) were very similar to those reported by Fortuna (2021) for a conventional cultivation system in São Paulo, Brazil, indicating good performance in terms of fresh cone production. The poorer development of the plants in G2, as shown by the lower values for fresh weight (Figure 7b and Table 3), is possibly due to the low soil pH (5.26) together with the exchangeable Al content of more than 0.30 cmol c kg -1 presented by 32% of the samples in this group, which is toxic to plants and seen as a threshold for soil correction (Freire et al., 2013). It should be noted that the soil of G2 has a clayey texture (530.2 g kg -1 ), which may have hampered plant development. The textural class of soil best suited to hop cultivation is sandy loam, which has up to 18% clay. Higher levels are detrimental to the crop and can make it more difficult for the hops to establish and produce new roots (Stein, 2020). The metal content of the plants followed the enrichment pattern of the pseudo-total content and/or bioavailable content of the soils, where the Ca, Na, Co, Cr, Cu, Zn and Mg content was greater in the lower part of the landscape (G1), and the Cd content was greater in the higher areas (G2). The median K concentration in the plant shoots was 8583.3 mg kg -1 in G1 and 22820.0 mg kg -1 in G2. Results very similar to those of G2 were found by Lafontaine et al. (2022) when evaluating the K content of different hop cultivars grown in the USA (mean value of 21630.40 mg kg -1 ) and Germany (mean value of 22906.29 mg kg -1 ). The high levels of both groups may be related to the high demand of the hops for this nutrient. K plays a key role in hop growth and controlling osmotic pressure, adjusting turgor, and controlling membrane polarization and protein biosynthesis (Chen et al., 2008), as well as significantly reducing the occurrence of pests and diseases (Ahmad et al., 2018). The K fertilizer (K 2 O) requirement for hops varies from 80 to 138 kg ha -1 (Neve, 1991). The chemical analysis of the soil (Table 1S) indicated a high K content (91-135 mg kg -1 ) in the soil of G1 (0.29 cmol c dm -3 , equivalent to 113.1 mg kg -1 ) and a low content (< 45 mg kg -1 ) in G2 (0.09 mg kg -1 , equivalent to 35.1 mg kg -1 ) (Freire et al., 2017). The low K content in the soil of G2 is possibly due to the nutrient being extracted by the plants. This is evidenced by the soil being collected at the same time as the plants and therefore representing the residual content of the nutrient in the soil. Furthermore, as discussed above, these areas are greatly influenced by the terrain, favoring the loss of K, which is highly soluble, to the lower part of the landscape. However, the importance of potassium fertilization when growing hops should be highlighted, as potassium is a fundamental element, in high demand by the crop for its development. Although the average K content of the plants (Table 2S) in G1 was lower (9637.3 mg kg -1 ) than in G2 (22820.0 mg kg -1 ), the accumulated content (25452.8 mg plant -1 ) was higher (Table 3S). This difference was possibly due to the dilution effect when assessing the total content of the plants, expressed in mg kg -1 . However, directly assessing K accumulation in the plants reflects the extraction potential of the plant in question, enabling more-refined fertilisation management. None of the plant samples exhibited high levels of either Cd or Pb. According to Young (1995), the levels commonly found for Cd and Pb in plants range from 0.2–0.8 and 0.1–10 mg kg -1 , respectively. Levels ranging from 5 to 30 mg kg -1 for Cd and from 30 to 300 mg kg -1 for Pb are considered toxic. Therefore, based on these results, despite the accumulation of these metals being more pronounced in G2, there is no risk of the plants being contaminated by Cd or Pb. The poor accumulation of some elements in the plants of both groups may reflect metal bioaccumulation in the roots, which did not favor translocation to the shoots or cones. However, it was not possible to collect the root system, as the plant is perennial and the research plan involved monitoring subsequent crop cycles at the same points. 5. Conclusion The areas of hop-production showed no significant metal enrichment of the soils, except for Cd, which presented from moderate to severe contamination. The type of terrain and (experimental) soil management in the areas of hop-production are the main factors that contribute to the transfer and accumulation of metals in the plants as well as to their development. This research offers unprecedented data on the behavior of hop cultivation in a mountainous agricultural area of Brazil, strengthening the knowledge base necessary to advance the tropicalization of hops, in addition to investigating the influence of different agricultural management practices on the quality of the soil and inflorescences of hops grown in a tropical region, generating scientific and technological insights to improve production systems. Declarations Funding Special thanks to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior and Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro for the financial support. The authors would like to thank Grupo Petrópolis for providing the experimental area for this research, as well as all the logistical and labor support for the maintenance of the area and team activities. The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Competing Interest The authors have no relevant financial or non-financial interests to disclose . Author Contributions All authors contributed to the study conception and design. The first draft of the manuscript was written by Mariana Ferreira Santa Cruz Coimbra and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Data Availability The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request References Ahmad, Z., Anjum, S.,Waraich, E.A., Ayub, M.M., Mhmad, T., Tariq, R.M.S., Ahmad, R., Iqbal, M.A., 2018. Growth, Physiology, and Biochemical Activities of Plant Responses with Foliar Potassium Application under Drought Stress. Journal of Plant Nutrition. 41, pp. 1734–1743. https://doi.org/10.1080/01904167.2018.1459688 Akter, M., Kabir, M. H., Alam, M. A, Al Mashuk, K., Rahman, M.M., Alam, M.S, Brodie, G., Islã, S. M. M., Gaihre, Y. K, Rahman, GKMM. 2023. Geospatial Visualization and Ecological Risk Assessment of Heavy Metals in Rice Soil of a Newly Developed Industrial Zone in Bangladesh. 15. https://doi.org/10.3390/su15097208 Ali, H., & Khan, E., 2019. Trophic transfer, bioaccumulation, and biomagnification of non-essential hazardous heavy metals and metalloids in food chains/webs—Concepts and implications for wildlife and human health. Human and Ecological Risk Assessment: An International Journal, 25 (6), pp. 1353-1376. Almaguer, C., Schönberger, C., Gastl, M., Arendt, E. K., Becker, T., 2014. Humulus lupulus – a story that begs to be told. Journal of the Institute of Brewing, v. 120, n. 4, pp. 289-314. https://doi.org/10.1002/jib.160 Alonso Esteban, J. I., Pinela, J., Barros, L., Ćirić, A., Soković, M., Calhelha, R. C., Torija-Isasa, E., Sánchez Mata, M. C., Ferreira, I. C. F. R., 2019. Phenolic composition and antioxidant, antimicrobial and cytotoxic properties of hop ( Humulus lupulus L.) seeds. Industrial Crops & Products, 134, 154-159. https://doi.org/10.1016/j.indcrop.2019.04.001 Amaral Sobrinho, N.M.B., Costa, L.M., Oliveira, C., Velloso, A.C.X., 1992. Metais pesados em alguns fertilizantes e corretivos. Revista Brasileira de Ciência do Solo, v.16, pp. 271276. ANVISA, 2023. Agência Nacional de Vigilância Sanitária – Órgão do Governo. Disponível em: https://www.gov.br/anvisa/pt-br (accessed 01 march 2024). Aquino, A. M. D., Teixeira, A. J., Fonseca, M. J. de O., Assis, R. L. D., Ozassa, T. I. "Produção de lúpulo na Região Serrana Fluminense: manual de boas práticas.", 2022. Associação Comercial, Industrial e Agrícola de Nova Friburgo – ACIANF. http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/1144201. (accessed 01 january 2024). Barker, A.V., Pilbeam, D. J.. Handbook of Plant Nutrition; Handbook of Plant Nutritioneds ; CRC Press: Boca Raton, FL, USA, 2015. https://doi.org/10.21273/hortsci.42.2.422b Biendl, M., 2009. Hops and health. Technical Quarterly. https://doi.org/10.1094/tq-46-2-0416-01 Bocquet, L., Sahpaz S., Hilbert J. L., Rambaud C., Rivière C., 2018. Humulus lupulus L., a very popular beer ingredient and medicinal plant: overview of its phytochemistry, its bioactivity, and its biotechnology. Phytochemistry Reviews. https://doi.org/10.1007/s11101-018-9584-y Brasil, 2023. Ministério da Agricultura e Pecuária. Anuário da Cerveja 2022 / Ministério da Agricultura e Pecuária. Secretaria de Defesa Agropecuária. – Brasília: MAPA/DAS. https://www.gov.br/agricultura/pt-br/assuntos/inspecao/produtos-vegetal/publicacoes/anuario-da-cerveja-2022/view. (accessed 01 march 2024). Campos, M. L., Silva, F. N. D. A., Furtini NETO, A. E., Guilherme, L. R. G., Marques, J. J., Antunes, A. S., 2005. Determinação de cádmio, cobre, cromo, níquel, chumbo e zinco em fosfatos de rocha. Pesquisa Agropecuária Brasileira, 40 (4), pp. 361 - 367. https://doi.org/10.1590/S0100-204X2005000400007 Catelli, E. G., 2022. Análise da presença de metais em cervejas artesanais e comercializadas no Paraná (Dissertação de bacharelado, Universidade Tecnológica Federal do Paraná). https://portaldeinformacao.utfpr.edu.br/Record/riut-1-30984/Details (accessed 01 february 2024). Chen, Y.-F., Wang, Y., Wu, W.-H, 2008. Membrane Transporters for Nitrogen, Phosphate and Potassium Uptake in Plants. Journal of Integrative Plant Biology, 50, 835 - 848. https://doi.org/ 10.1111/j.1744-7909.2008.00707.x Durello, R. S., Silva, L. M., Bogusz J. R. S., 2019. Química do lúpulo. Química Nova, São Paulo, 42 (8), pp. 900-919. https://www.scielo.br/pdf/qn/v42n8/0100-4042-qn-42-08-0900.pdf (accessed 02 april 2024). Fadigas, F. D. S., Amaral-Sobrinho, N. M. B. D., Mazur, N., Anjos, L. H. C. D., & Freixo, A. A. (2002). Concentrações naturais de metais pesados em algumas classes de solos brasileiros. Bragantia, 61, pp. 151-159. https://doi.org/10.1590/S0006-87052002000200008 FAO – Food and Agriculture Organization, 2024. https://www.fao.org/land-water/land/en/ (accessed 07 april 2024). Fortuna, G. C., Gomes, J. A. D. O., Campos, O. P., Neves, C. S., & Bonfim, F. P. G. (2023). Desempenho agronômico de variedades de Humulus lupulus L. cultivadas em sistema orgânico e convencional no centro-oeste paulista, Brasil. Ciência Rural, 53. https://doi.org/10.1590/0103-8478cr20210704 Franco, T. F., Lima, E. S. A., Amaral Sobrinho, N. M. B., Carmo, M. G. F., Breda, F. A. F., 2020. Enrichment and bioavailability of toxic lements in intensive vegetable production areas. Revista Caatinga. 33, pp. 124 – 134. https://doi.org/10.1590/1983-21252020v33n114rc Freire, L. R., Balieiro, F. C., Zonta, E., Anjos, L. H. C, Pereira, M. G, Lima, E., Guerra, J. G. M., e Ferreira, M. B. C., 2013. Manual de calagem e adubação do estado do Rio de Janeiro . EDUR. https://www.embrapa.br/busca-de-publicacoes/-/publicacao/963089/manual-de-calagem-e-adubacao-do-estado-do-rio-de-janeiro. (accessed 02 march 2024). Freitas, C. F. Grupo Petrópolis inicia vendas de lúpulo brasileiro em pellets e mira em microcervejarias. Catalisi. https://catalisi.com.br/grupo-petropolis-inicia-vendas-de-lupulo-brasileiro-em-pellets-e-mira-em-microcervejarias/ (accessed 18 january 2024). Fruszecka-Kosowska, A., Baran, A., Wdowin, M., Mazur-Kajta, K., Czech, T., 2020. The contents of the potentially harmful elements in the arable soils of southern Poland, with the assessment of ecological and health risks: a case study. Environmental Geochem Health 42, https://doi.org/10.1007/s10653-019-00372-w Gingrich, G.; Hart, J.; Christensen, N. Hops; Oregon State University, Extension Service: Corvallis, OR, USA, 1994. https://ir.library.oregonstate.edu/concern/administrative_report_or_publications/0g354f82t (accessed 01 february 2025). Grisel, P. N. e Assis, R. N., 2015. Dinâmica agrária da Região Sudoeste do município de Nova Friburgo e os atuais desafios de sua produção hortícola familiar. Documentos nº 299, Embrapa Agrobiologia, Seropédica. http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/1015689. (accessed 15 march 2024). Gonçalves, R. G. M., Santos, C. A., Breda, F. A. F., Lima, E. S. A. L., Carmo, M. G. F., Souza, C. C. B., Amaral Sobrinho, N. M. B., 2022. Cadmium and lead transfer factors to kale plants (Brassica oleracea var. acephala) grown in mountain agroecosystem and its risk to human health. Environmental monitoring and assessment, 194, 366. https://doi.org/10.1007/s10661-022-10035-6 Jia, Y., Wang, L., Qu, Z., Yang, Z., 2018. Distribution, contamination and accumulation of heavy metals in water, sediments, and freshwater shellfish from Liuyang River, Southern China. Environmental Science and Pollution Research, 25(7), pp. 7012-7020. Jiang, C. H., Sun, T. L., Xiang, D. X., Wei, S. S., Li, W. Q., 2018. Anticancer activity and mechanism of xanthohumol: a prenylated flavonoid from hops ( Humulus lupulus L.). Frontiers in Pharmacology, v. 9, n. 530, pp. 1-13. https://doi.org/10.3389/fphar.2018.00530 Johnsen, I. V., Aaneby, J., 2019. Soil intake in ruminants grazing on heavy-metal contaminated shooting ranges. Science of the Total Environment687, pp. 41–49. https://doi.org/10.1016/j.scitotenv.2019.06.086 Kabata-Pendias, A., 2011. Trace Elements in Soils and Plants. CRC Press, Taylor and Francis Group. Boca Raton. https://doi.org/10.1201/b10158 Khan, S., Cao, Q., Zheng, Y. M., Huang, Y. Z., Zhu, Y. G., 2008. Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China. Environmental Pollution 152, 686–692. https://doi.org/10.1016/j.envpol.2007.06.056 Kumar, A., Tripti, Raj, D., Maiti, S. K., Maleva, M., Borisova, G., 2022. Soil Pollution and Plant Efficiency Indices for Phytoremediation of Heavy Metal(loid)s: Two-Decade Study (2002–2021). Metals (Basel). https://doi.org/10.3390/met12081330 Lafontaine, S., Thomson, D., Schubert, C., Müller, I., Kyle, M., Biendl, M., & Rettberg, N., 2022. How deviations in the elemental profile of Humulus lupulus grown throughout the US and Germany influence hop and beer quality. Food chemistry , 395, 133543. https://doi.org/10.1016/j.foodchem.2022.133543 Lima, E.S.A., Matos. T de S., Pinheiro, H. S. K., Guimarães, L. D. D., Pérez, D. V., Amaral Sobrinho, N. M. B., 2018. Soil heavy metal content on the hillslope region of Rio de Janeiro, Brazil: reference values. Environmental monitoring and assessment, 190, nº 6, pp. 1-11. https://doi.org/10.1007/s10661-018-6736-x Liu, Z., Waang, Y., e Liu, Y., 2019. Geographical origins and varieties identification of hops ( Humulus lupulus L.) by multi-metal elements fingerprinting and the relationships with functional ingredients. Food Chemistry, 289, 522–530. https://doi.org/10.1016/j.foodchem.2019.03.099 Neve, R.A., 1991. Hops, Chapman and Hall: London, UK. Oliveira, L. F. C., Lemke-de-Castro, M. L., Rodrigues, C., Borges, J. D., 2010. Isotermas de sorção de metais pesados em solos do cerrado de Goiás. Revista Brasileira de Engenharia Agrícola e Ambiental, v. 14, n. 7, pp. 776-782. https://doi.org/10.1590/s1415-43662010000700014 Sarmento, R. R., 2017. Fracionamento Geoquímico de Zn, Ni e Cd em Solos da Região Serrana – RJ: Valores de Referência de Biodisponibilidade e Avaliação da Contaminação em Áreas Cultivadas com Hortaliças de Folha. https://rima.ufrrj.br/jspui/handle/20.500.14407/15825. (accessed 15 March 2024). Siqueira, J. H., Santana, N. M. T., Pereira, T. S. S., Moreira, A. D., Benseñor, I. M., Barreto, S. M. e Molina, M. D. C. B., 2021. Consumo de bebidas alcoólicas e não alcoólicas: Resultados do ELSA-Brasil. Ciência & Saúde Coletiva, 26, 3825-3837. https://doi.org/10.1590/1413-81232021269.2.30682019 Spósito, M. B, Ismael, R. V., Barbosa, C. M. A., Tagliaferro, A. L., 2019. A cultura do lúpulo. Piracicaba, SP: Esalq - Divisão de Biblioteca, pp. 81. (Série Produtor Rural, 68). https://www.researchgate.net/profile/Caio-Morais-De-Alcantara-Barbosa/publication/334672293_A_Cultura_do_Lupulo/links/5d3dcb5a299bf1995b524c08/A-Cultura-do-Lupulo.pdf (accessed 15 January 2024). Stein, A. J. K., 2020. Lúpulo do Brasil: Introdução ao cultivo e manejo. (SteinHops - Lúpulo do Brasil), 2020, pp. 18. Kindle Edition. Teixeira P. C., Donagemma G. K., Fontana A., Teixeira W. G., 2017. EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária. Manual de métodos de análise de solo. Ed. Brasília, DF: Embrapa. pp. 574. Teixeira, A. J.; Aquino, A. M. de; Macedo, J. R. de, 2022. EMBRAPA. Recomendações preliminares de calagem e adubação para a cultura do lúpulo. https://www.embrapa.br/busca-de-publicacoes/-/publicacao/1144211/recomendacoes-preliminares-de-calagem-e-adubacao-para-a-cultura-do-lupulo?utm_source. (accessed 17 june 2025). USEPA., 1996. Digestão ácida de sedimentos, lamas e solos - método EPA 3050B. Agência de Proteção Ambiental dos Estados Unidos., https://www.epa.gov/sites/production/fles/2015-06/documents/epa-3050b.pdf. (accessed 15 january 2025). USEPA., 2008. Extração ácida de sedimentos, lodos e solos - método EPA 3050. Agência de Proteção Ambiental dos Estados Unidos. http://www.epa.gov/waste/hazard/testmethods. (accessed 15 january 2025). Wu, S., Peng, S., Zhang, X., Wu, D., Luo, W., Zhang, T., Wu, L., 2015. Levels and health risk assessments of heavy metals in urban soils in Dongguan, China. Journal of Geochemical Exploration, 148, pp. 71-78. https://doi.org/10.1016/j.gexplo.2014.08.009 Zoffoli, H. J. O., Do Amaral-Sobrinho, N. M. B., Zonta, E., Luisi, M. V., Marcon, G., Tolón Becerra, A., 2013. Inputs of heavy metals due to agrochemical use in tobacco fields in Brazil’s Southern Region. Environ Monit Assess 185, 2423–2437. https://doi.org/10.1007/s10661-012-2721-y Young, S., 1995. Toxic metals in soil-plant systems. The Journal of Agricultural Science . https://doi.org/10.1017/s0021859600071422 Tables Table 1 Set up, altitude and area of hop-production Areas 1, 2, 3 and 4 in Teresópolis in the mountainous region of Rio de Janeiro. Set up period (semester) Altitude (m) Area (ha) Area 1 5 820 0.4 Area 2 5 848 - 856 1.3 Area 3 5 856 - 923 0.8 Area 4 1 828 0.2 Table 2 Average levels of heavy metals present in the mineral fertilizers and organic manure (chicken litter) used in the study area. Element Mineral Fertilizer Organic Fertilizer ------------------------------- mg kg -1 cp -1 ------------------------------ Cd 1.38 0.55 Co ND 1,72 Cr 2.16 8.06 Cu 2.83 249.08 Mn 7.62 365.14 Ni 0.65 3.87 Pb 15.33 4.56 Zn 3.72 298.20 cp – comercial product; ND – not detectable. Table 3 Mean, median, minimum and maximum values for fresh and dry weight of the aerial part of the plantas (FAPW and DAPW) and cones (FCnW and FCnW), with the number (NCn) of cones for each group formed in the cluster analysis. ------------------------G1--------------------- ----------------------G2------------------ Mean Median Minimum Maximum Mean Median Minimum Maximum FAP (kg) 2.34 0.99 0.31 6.73 1.38 1.51 0.52 2.51 DAPW (kg) 1.14 0.32 0.11 3.73 0.78 1.03 0.17 1.19 NCn (unit) 1141.74 500.00 28.00 3100.00 ND ND ND ND FCnW (kg) 1.06 0.37 0.06 3.70 ND ND ND ND FCnW (kg) 0.38 0.21 0.02 0.98 ND ND ND ND ND = not detectable. Table 4 Mean, median, minimum and maximum values for the nutrient and heavy metal content in the cones from G1. ----------------------------------G1---------------------------------- Mean Median Minimum Maximum AlCn (mg kg -1 ) 227.45 177.33 35.33 519.33 CdCn (mg kg -1 ) 0.04 ND ND 0.50 CoCn (mg kg -1 ) 0.18 ND ND 0.93 CrCn (mg kg -1 ) ND ND ND ND CuCn (mg kg -1 ) 6.01 6.20 3.10 12.20 FeCn (mg kg -1 ) 233.82 219.10 131.10 407.10 MnCn (mg kg -1 ) 36.88 33.60 24.70 58.07 NiCn (mg kg -1 ) 0.37 ND ND 10.80 PbCn (mg kg -1 ) 1.35 1.00 ND 7.00 ZnCn (mg kg -1 ) 45.73 43.09 33.98 89.05 CaCn (mg kg -1 ) 18177.89 16497.60 11832.00 28708.80 MgCn (mg kg -1 ) 6295.10 5745.44 3726.08 12158.88 NaCn (mg kg -1 ) 400.00 0.37 0.20 0.72 KCn (mg kg -1 ) 22350.00 21.15 18.42 30.15 PCn (mg kg -1 ) 325.8 290.7 155.7 533.2 ND = not detectable. Supplementary Files SupplementaryTables.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-7285459","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":495307593,"identity":"b6821e2e-f6bd-41a2-a0cd-c176cb444526","order_by":0,"name":"Mariana Ferreira Santa Cruz Coimbra","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2UlEQVRIiWNgGAWjYDAC5gMgUoLBgIGB8QGQxcNHUAtbAlwLswFICxuRWhhAWtgkwAKEdOi2sT/88KPCItpc+vCzyq85djJsDMwPH93Ao8XsGI+xZM8ZidydfWlmt2W3JQMdxmZsnINPy/0eNmbGNoncDWcYzG5LbmMGauFhk8ar5Rj7M6gW9m/FktvqidHCYAbVwmPG+HHbYWK0wPzSw1MszbjtOA8bMyG/HAOHWF3udh72jR9/bqu252dvfvgYnxYUwMwDJolVDgKMP0hRPQpGwSgYBSMGAACzeUIpOwiCJwAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0003-0335-3533","institution":"UFRRJ: Universidade Federal Rural do Rio de Janeiro","correspondingAuthor":true,"prefix":"","firstName":"Mariana","middleName":"Ferreira Santa Cruz","lastName":"Coimbra","suffix":""},{"id":495307594,"identity":"585083c5-ed47-44f3-af4c-e9e2603f63b9","order_by":1,"name":"Ingrid Lobo da Silva Coêlho","email":"","orcid":"","institution":"UFRRJ: Universidade Federal Rural do Rio de Janeiro","correspondingAuthor":false,"prefix":"","firstName":"Ingrid","middleName":"Lobo da Silva","lastName":"Coêlho","suffix":""},{"id":495307595,"identity":"8b899587-8fe6-4277-b455-c6dfc8584051","order_by":2,"name":"Maria Gabriela Alves da Cruz","email":"","orcid":"","institution":"UFRRJ: Universidade Federal Rural do Rio de Janeiro","correspondingAuthor":false,"prefix":"","firstName":"Maria","middleName":"Gabriela Alves da","lastName":"Cruz","suffix":""},{"id":495307596,"identity":"296f3fc0-26eb-426d-af12-b177cdee1889","order_by":3,"name":"Eduardo Pereira da Rocha","email":"","orcid":"","institution":"UFRRJ: Universidade Federal Rural do Rio de Janeiro","correspondingAuthor":false,"prefix":"","firstName":"Eduardo","middleName":"Pereira da","lastName":"Rocha","suffix":""},{"id":495307597,"identity":"58349dba-09d4-4c16-8502-94890d96a344","order_by":4,"name":"Farley Alexandre da Fonseca Breda","email":"","orcid":"","institution":"UFRRJ: Universidade Federal Rural do Rio de Janeiro","correspondingAuthor":false,"prefix":"","firstName":"Farley","middleName":"Alexandre da Fonseca","lastName":"Breda","suffix":""},{"id":495307598,"identity":"04500b90-88e4-435a-b747-3c79d833bac3","order_by":5,"name":"Nelson Moura Brasil do Amaral Sobrinho","email":"","orcid":"","institution":"UFRRJ: Universidade Federal Rural do Rio de Janeiro","correspondingAuthor":false,"prefix":"","firstName":"Nelson","middleName":"Moura Brasil do Amaral","lastName":"Sobrinho","suffix":""},{"id":495307599,"identity":"cdb7b4dc-2fd0-4409-a3f1-f374702e545f","order_by":6,"name":"Erica Souto Abreu Lima","email":"","orcid":"","institution":"UFRRJ: Universidade Federal Rural do Rio de Janeiro","correspondingAuthor":false,"prefix":"","firstName":"Erica","middleName":"Souto Abreu","lastName":"Lima","suffix":""}],"badges":[],"createdAt":"2025-08-03 21:28:54","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7285459/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7285459/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":88450658,"identity":"3ba1fc0b-e507-43ed-8522-66340b0e0d2b","added_by":"auto","created_at":"2025-08-06 14:24:57","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":108614,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eArea of hop-production in Teresópolis, Rio de Janeiro, showing the areas under study.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/f0be14fc65eaa7f231d7a50f.jpg"},{"id":88451048,"identity":"c672431d-1aaa-419b-8b0a-cc6791fe067a","added_by":"auto","created_at":"2025-08-06 14:32:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":102019,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePollution index (PI) for metals in the soils of areas of hop-production in the mountainous region of Rio de Janeiro.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/32ac87cfd7400ab39f585055.png"},{"id":88450660,"identity":"58b917bf-9ec7-4a66-8521-3cfba723bbf7","added_by":"auto","created_at":"2025-08-06 14:24:57","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":49556,"visible":true,"origin":"","legend":"\u003cp\u003ePollution index for Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al in soil samples from an area of hop-production in the mountainous region of Rio de Janeiro.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/6c0cd53b0a32967280f842dd.jpg"},{"id":88450661,"identity":"6bc1447f-7e76-48a5-b081-44d9d9d597a1","added_by":"auto","created_at":"2025-08-06 14:24:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":58556,"visible":true,"origin":"","legend":"\u003cp\u003eBiplot of the Principal Component Analysis between the pollution indexes (PI) of metals and the soil attributes.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/6f9a34973409e10e6758f774.png"},{"id":88450666,"identity":"82abfb3e-76b9-4328-8451-98bba9c71d02","added_by":"auto","created_at":"2025-08-06 14:24:57","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":25566,"visible":true,"origin":"","legend":"\u003cp\u003eDendrogram based on the cluster analysis of soil samples from hop-growing areas, using Ward's method and the Euclidean distance, as a function of the pseudo-total metal content.\u003c/p\u003e","description":"","filename":"Figure5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/fe9d6fbf4d69fb093c13a67c.jpg"},{"id":88451049,"identity":"cc774776-cfed-465f-921a-4a8725afdbaa","added_by":"auto","created_at":"2025-08-06 14:32:57","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":24974,"visible":true,"origin":"","legend":"\u003cp\u003eStandardized mean values for the pseudo-total levels of heavy metals in the chemical, particle-size and elevation attributes of the soils, considering the two groups (G1 and G2) formed in the cluster analysis of samples collected in areas of hop-production in the Mountainous Region of Rio de Janeiro.\u003c/p\u003e","description":"","filename":"Figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/63cbf20649d3311f9e1a9a6d.png"},{"id":88450667,"identity":"5112606d-2a0f-4e7f-a80f-cbb205b43111","added_by":"auto","created_at":"2025-08-06 14:24:57","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":70839,"visible":true,"origin":"","legend":"\u003cp\u003eStandardized mean values for the bioavailable levels of the elements in the soil (A); fresh and dry aerial part weight of the plants (FAPW and DAPW) (B),; accumulated levels in the leaves and steams of the plant (LS) (C), and accumulated levels in aerial part (AP) of the plant (D), for each group formed in the cluster analysis.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/95614df58363bb4e9e6b03c0.png"},{"id":89845248,"identity":"07ad53cb-1f29-4682-b5ef-4dea38aee111","added_by":"auto","created_at":"2025-08-25 16:06:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1195796,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/5fc93c0e-d854-4491-87d3-80758e66d590.pdf"},{"id":88450677,"identity":"b5be6124-e255-4fe9-b9d7-018b44d1122e","added_by":"auto","created_at":"2025-08-06 14:24:57","extension":"docx","order_by":16,"title":"","display":"","copyAsset":false,"role":"supplement","size":30588,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryTables.docx","url":"https://assets-eu.researchsquare.com/files/rs-7285459/v1/02bc733c41705f9ddbcd94b0.docx"}],"financialInterests":"","formattedTitle":"Factors Influencing the Development and Accumulation of Heavy Metals in Hop Plants Grown in Tropical Regions","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eHops are a plant of family Cannabaceae, genus Humulus, species \u003cem\u003eHumulus lupulus\u0026nbsp;\u003c/em\u003eL., which has been cultivated for centuries in countries with temperate climates and a marked photoperiod (14-16h), such as Germany and Belgium, where they are harvested annually\u0026nbsp;(Bocquet et al., 2018).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIt is characterized as a perennial, herbaceous, dioecious, anemophilous and rhizomatous climbing plant, which produces inflorescences that, when mature, are known as cones (Durello et al., 2019). In the basal area of the cones, glands that are responsible for secreting a type of yellowish pollen (called lupulin), synthesize and store volatile compounds, such as essential oils and alpha and beta acids (Almaguer et al., 2014; Durello et al., 2019). These compounds are important raw materials for the brewing industry, affording beer its bitterness, aroma and flavor; while in the pharmaceutical industry, they have a beneficial effect in treating disorders and diseases such as cancer (Jiang et al., 2018; Alonso-Esteban et al., 2019; Sp\u0026oacute;sito et al., 2019).\u003c/p\u003e\n\u003cp\u003eAccording to the Beer Yearbook 2022, published by the Ministry of Agriculture and Livestock, Brazil is the third largest producer and consumer of beer in the world (Brasil, 2023).\u0026nbsp;However, production of the ingredients needed to make beer remains low, meaning the country is a major importer of these raw materials, especially hops (Dagostin, 2019). Given the demand, it is extremely important to conduct studies that evaluate the adaptation and production of this ingredient to meet the needs of the domestic market.\u003c/p\u003e\n\u003cp\u003eHop cultivation is relatively new to Brazil, but has already proven viable in several areas, giving two harvests per year in various regions, including the states of Rio Grande do Sul, Santa Catarina, Paran\u0026aacute;, S\u0026atilde;o Paulo, Rio de Janeiro, Minas Gerais and the Federal District (Sp\u0026oacute;sito et al., 2019; Aquino et al., 2022). Although the latitudes are not considered ideal for the crop, proper management and the selection of varieties that are adapted to tropical environments mean that such initiatives are relatively successful (Aquino et al., 2022;\u0026nbsp;Durello et al., 2019).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAccording to Aquino et al. (2022), the nutritional requirement of hops is high due to their rapid growth and large size, resulting in the accumulation of significant amounts of shoot biomass.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn hop cultivation, N is normally applied at a rate of between 180 and 220 kg ha\u003csup\u003e-1\u003c/sup\u003e (Teixeira et al, 2022), depending on the organic matter content of the soil. However, its P requirement is relatively low, estimated at 7.5 to 9 kg P\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u0026nbsp;\u003c/sub\u003eha\u003csup\u003e-1\u003c/sup\u003e (Gingrich et al., 1994). Another basic macronutrient for hop growth is potassium (K), which helps in adjusting turgor and controlling osmotic pressure, membrane polarization and protein biosynthesis (Chen et al., 2008). \u0026nbsp;The crop demand for K, applied as K\u003csub\u003e2\u003c/sub\u003eO, ranges from 80 to 138 kg ha\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003e,\u003csup\u003e\u0026nbsp;\u003c/sup\u003eand the use of K significantly reduces the occurrence of pests and diseases (Barker and Pilbeam, 2015),.\u003c/p\u003e\n\u003cp\u003eConsiderable quantities of nutrients are exported from the soil during the crop cycle through successive cone harvests and pruning of the foliage. It is therefore crucial to replace these nutrients using strategies that favor the productive capacity of the soil\u0026nbsp;(Aquino et al., 2022).\u003c/p\u003e\n\u003cp\u003eHowever, there is still little information regarding specific management strategies for cultivating hops in tropical regions, particularly in relation to fertilization, and especially under the soil and climate conditions of Brazil\u0026nbsp;(Stein, 2020). Many of these strategies are still in the experimental phase, where doses of mineral and organic fertilizers are tested with a view to increasing cone productivity, thereby reducing dependence on inputs that are generally imported by the beer industry. According to Sp\u0026oacute;sito et al. (2019), almost all knowledge of the crop and management practices are based on research carried out in regions with a temperate climate, similar to that of its place of origin, with little research in regions with a subtropical or tropical climate.\u003c/p\u003e\n\u003cp\u003eAs soil fertility is fundamental to hop cultivation, effective crop management requires a combination of strategies to ensure adequate plant nutrition without compromising the quality of the end product (the cone) or the environment, especially regarding the accumulation of potentially toxic\u0026nbsp;elements in the soil and plants (Teixeira et al., 2022).. It is therefore essential to consider not only the amount of fertilizer, but also sustainable methods of ensuring soil fertility.\u003c/p\u003e\n\u003cp\u003eVarious studies have demonstrated an increase in the concentration of heavy metals in agricultural areas in the mountainous region of Rio de Janeiro (Franco et al., 2020), and point out that one of the main sources of contaminants in areas of agricultural production is linked to the intensive use of such inputs as synthetic and soluble fertilizers, as well as organic waste, i.e. poultry litter, which include these elements due to impurities from the production process (Sousa et al., 2020; Gon\u0026ccedil;alves et al., 2022).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIt should be noted that heavy metals can enter the soil through natural processes (Jia et al., 2018) and the excessive use of chemical products, and can lead to contamination and significant environmental problems (Akter et al., 2023) due to the toxicity and persistence of these elements in the environment (Ali et al., 2019).\u003c/p\u003e\n\u003cp\u003eIn view of the above, the aim of this study was to characterize a reference area for \u003cem\u003eHumulus lupulus\u0026nbsp;\u003c/em\u003eL. production in Brazil in terms of contamination by heavy metals (Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al) and their transfer to the plants, especially to the cones, as well as identifying the environmental factors that most influence development and production in the crop.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cp\u003e2.1 Study area\u003c/p\u003e\n\u003cp\u003eSoil and plant samples were collected from a property used for hop production (Fazenda S\u0026atilde;o Francisco Farm) in the district of Teres\u0026oacute;polis in the mountainous region of Rio de Janeiro, belonging to the Grupo Petr\u0026oacute;polis national beverage company (GP). Four areas were studied (Figure 1) that present different types of relief and cultivar production, and are managed using soluble mineral fertilizers and organic waste (poultry litter).\u003c/p\u003e\n\u003cp\u003eThe study area has a history of dairy cattle production, and for many years was covered by pasture, which led to a level of chemical and physical degradation of the soil. However, in 2018, the GP Hop Program was initiated, which currently includes more than 21,000 plants at the Fazenda S\u0026atilde;o Francisco Farm in an area of approximately 5 ha (Freitas, 2022).\u003c/p\u003e\n\u003cp\u003e2.2 Collecting the samples, with information on the management of each area\u003c/p\u003e\n\u003cp\u003eSingle soil samples were collected from 42 points at depths of 0-0.2 m and 0.2-0.4 m, with the plant samples collected at the same locations. It should be noted that some plants had not completed their cycle, making it impossible to collect cones in areas 2 and 3.\u003c/p\u003e\n\u003cp\u003eNitrogen, phosphate and potassium mineral fertilizers as well as organic fertilizer (poultry litter) were applied to each area considering a spacing between plants of 2 m x 1 m and 3 m x 1 m. In addition, products were periodically applied to control pests and diseases, such as Bordeaux mixture to control mildew, a recurrent disease in the crop. It should be noted that the areas were set up at different times (Table 1).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Set up, altitude and area of hop-production Areas 1, 2, 3 and 4 in Teres\u0026oacute;polis in the mountainous region of Rio de Janeiro.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSamples of chemical fertilizer (nitrogen, potassium and phosphate) and organic fertilizer (chicken litter) were also collected in the study area. The samples were dried in a forced air circulation oven at 60\u0026deg;C to constant weight then ground and macerated. After preparation, they were digested and analyzed as per method 3050B of the United States Environmental Protection Agency (US EPA, 1996) to determine the levels of Cd, Cr, Cu, Mn, Ni, Pb and Zn. The extracts were quantified by atomic absorption spectrometry using the Varian SpectrAA 55B (Agilent Technologies) (Table 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Average levels of heavy metals present in the mineral fertilizers and organic manure (chicken litter) used in the study area.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e2.3 Preparing and analyzing the soil samples\u003c/p\u003e\n\u003cp\u003eThe soil samples were air-dried, crushed, sieved through a 2-mm mesh and homogenized to determine the chemical and physical attributes of the soil. They were then macerated in an agate mortar and sieved through a 0.150-mm mesh to determine the levels of metal bioavailability (F1+F2).\u003c/p\u003e\n\u003cp\u003eThe soil samples were analyzed in triplicate for organic carbon (Corg); pH (H\u003csub\u003e2\u003c/sub\u003e0); pH (KCl); exchangeable bases such as calcium (Ca), magnesium (Mg), sodium (Na) and potassium (K); exchangeable aluminum (Al); assimilable phosphorus (P); potential acidity (H+Al); sum of bases (SB); base saturation (V%) and cation exchange capacity (CEC), as per EMBRAPA methodology (Teixeira et al., 2017).\u003c/p\u003e\n\u003cp\u003eThe 3050B method proposed by the United States Environmental Protection Agency (US EPA, 1996) was used to determine the pseudo-total metal content (Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al). The extracts were quantified by atomic absorption spectrometry using the Varian SpectrAA 55B (Agilent Technologies).\u003c/p\u003e\n\u003cp\u003eSRM 2709 San Joaquin Soil, certified by the National Institute of Standards and Technology\u003cem\u003e\u0026nbsp;\u003c/em\u003e(NIST, USA), was used as the reference to validate the analytical method. The results for recovery of the reference material were within the ranges accepted by NIST as normal for soil samples, with recovery values greater than 95%.\u003c/p\u003e\n\u003cp\u003e2.4 Preparing the plant samples\u003c/p\u003e\n\u003cp\u003eThe collected plants were harvested at the peak of cone maturation, albeit at different times in the four areas under analysis. The plants were cut at the base of the stem and the shoots carefully removed in the field. They were then separated, stored in paper bags and properly identified. The plant material was weighed to determine the fresh weight and then dried in a forced circulation oven at 60\u0026deg;C to constant weight to obtain the dry weight. After weighing, the samples were crushed in an IKA A11 analytical mill and stored in paper bags for later chemical analysis.\u003c/p\u003e\n\u003cp\u003e2.5 Determining the levels of Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al in the plant material.\u003c/p\u003e\n\u003cp\u003eTo determine the total metal and nutrient content of the shoots (leaves and stems) and cones, the prepared samples were weighed in triplicate and then digested using EPA method 3050 (United States Environmental Protection Agency - US EPA, 2008). The resulting extracts were analyzed by atomic absorption spectrometry to determine the metal content. Na and K were analyzed using flame photometry.\u003c/p\u003e\n\u003cp\u003eThe quality of the analytical procedures was verified using the SRM 1573a reference material (tomato leaves), certified by the National Institute of Standards and Technology (NIST, 2018). The recovery rates for Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al were considered adequate, with recovery values greater than 90%.\u003c/p\u003e\n\u003cp\u003e2.6 Pollution Index (PI)\u003c/p\u003e\n\u003cp\u003eThe pollution index (PI) was determined to assess the enrichment or depletion of the soil in relation to the presence of metals (Khan et al., 2008). The PI was obtained from the ratio between the current pseudo-total concentration of each metal (Cn) in the soil sample and its respective quality reference value, also known as the geochemical background (PI = Cn/QRV) (USERO et al., 1997), where PI is the pollution index, Cn is the concentration of heavy metal in the soil and QRV is the quality reference value. The reference values used in this study were based on Lima et al. (2018).\u003c/p\u003e\n\u003cp\u003eThe PI indicates the degree of metal contamination of the soil, classified as per Wu et al. (2015): a) PI \u0026le; 1 (not contaminated); b) 1 \u0026lt; PI \u0026le; 3 (low contamination); c) 3 \u0026lt; PI \u0026le; 5 (moderate contamination); d) PI \u0026gt; 5 (severe contamination).\u003c/p\u003e\n\u003cp\u003e2.7 Statistical analysis\u003c/p\u003e\n\u003cp\u003eThe statistical analysis included both descriptive and multivariate analysis tools. Descriptive analysis of the metal content of the soil and plants, fresh and dry plant weight, soil attributes, bioaccumulation factor and pollution index was carried out using positional (mean and median) and amplitude parameters (minimum, maximum and standard deviation) in Microsoft\u003csup\u003e\u0026reg;\u003c/sup\u003e Office Excel\u003csup\u003e\u0026reg;\u003c/sup\u003e. Box plots were generated using the SigmaPlot 12.5 software.\u003c/p\u003e\n\u003cp\u003eThe multivariate procedures included cluster analysis and discriminant analysis. For the cluster analysis, the Euclidean distance was used as a measure of similarity, while the Ward hierarchical method was adopted as the clustering algorithm, which minimizes the sum of squares (SQ) within each group, generating more homogeneous groups with each grouping (Hair et al., 2005). For this, the pseudo-total values of the elements Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al were used as grouping variables. The results were standardized to mean 0 and variance + or -1. To interpret and form the groups, a value equal to 1.25 times the standard deviation of the linkage distance of all the observations was adopted as the cut-off point for the dendrogram (Milligan \u0026amp; Cooper, 1985). Validation and the appropriate number of groups were performed by cross-validation in discriminant analysis, using the same discriminating variables used in the grouping, assuming equality of the covariance matrix and an equal likelihood of classification for the groups.\u003c/p\u003e\n\u003cp\u003ePrincipal component analysis (PCA) using the R software (R Core Team, version 3.4.4) was used to relate the data on soil fertility (P, pH, Ca, Mg, Na, K, H+Al, V, CEC, SB and CO), particle size, elevation, pseudo-total values for Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al in the soil, bioaccumulation factor (BAF) in the shoots (Pa) and cones (Cn), pollution index (PI), and total accumulated levels of Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al, Ca and Mg in the shoots and cones of the plants.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003e3.1 Assessing enrichment of the\u0026nbsp;pollution index\u003c/p\u003e\n\u003cp\u003eWhen analyzing Figure 2, the median values of the pollution index (PI) for each of the metals under analysis are below 3 (green line) indicating no contamination (PI \u0026le; 1) or very little contamination (1 \u0026lt; PI \u0026lt;3) at most of the points where the soil samples were collected. However, for Cd, despite most of the samples showing low contamination, there was a wide range of PI values (0 to 41), with some points showing severe contamination (PI \u0026gt; 5), which may represent a risk to the environment and to any plants grown in these areas.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFigure 3 shows the percentage of soil samples within each class proposed by Wu et al. (2015) for each metal. For Ni, Co and Cr, 100% of the samples had PI values of less than one. As a result, it is thought that the levels of these elements remaining in the soil after the hop harvest are of lithogenic origin. PI values greater than one were seen for Cd, Cu, Mn, Pb and Zn at certain points, confirming enrichment of these metals in some areas, albeit poor for most of the samples.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTherefore, for a better understanding of the factors involved in the dynamics of these metals in the soil and their enrichment in areas of hop production, Principal Component Analysis (PCA) was carried out between the PI for Cd, Cu, Mn, Pb and Zn and the soil attributes (Figure 4).\u003c/p\u003e\n\u003cp\u003eAccording to the biplot graph obtained with the PCA between the soil attributes and the pollution indices (PI) for the metals (Figure 4), it can be seen that in CP1 (the component that explains 47.65% of the variance in the data), PICd shows a positive relationship with the potential acidity of the soil (H+Al), CEC, pseudo-total levels of Al and Fe, clay content and elevation (Elev), and an inverse relationship with soil pH. CP2 shows a possible, albeit poorer, relationship with COrg, which is related to the CEC. It should be noted that these two components together explain 59.82% of the accumulated variance in the data. Furthermore, there was no relationship between Ca, Mg, K or P and PICd. For Cu, Mn, Pb and Zn, the PI showed a close positive relationship with the Ca, Mg, P and K content, and an inverse relationship with elevation, demonstrating the influence of the soluble fertilizers and correctives used in the area on the enrichment of these metals; as well as the influence of the terrain, which possibly favored soil being dragged from the surface layer, exposing the sub-surface layer and facilitating the transport of these elements from the highest to the lowest point in the landscape.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e3.2 Characterization of groups of soil samples from an area of hop-production in the mountainous region of Rio de Janeiro\u003c/p\u003e\n\u003cp\u003eCluster analysis was carried out to identify groups of samples with a similar metal content in the areas of hop-production, and to determine the characteristics that contribute to the differences. The analysis was based on the pseudo-total levels of Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn and Al.\u003c/p\u003e\n\u003cp\u003eFigure 5 shows the dendrogram obtained from the cluster analysis. To define the number of groups to be adopted, a linkage distance of 0.045 was used as the cut-off point in the dendrogram, this value being 1.25\u0026nbsp;times the standard deviation of the linkage distance of all the observations (Milligan and Cooper, 1985), and suggests the formation of up to seven groups.\u0026nbsp;To help choose the appropriate number of groups, cross-validation in discriminant analysis (DA) was applied, which indicated the formation of two groups to be the most appropriate, as this had the lowest rate of error (\u0026lt; 0.1 per cent) and made it easier to explain the variability in the samples. The two groups were Group 1 (G1) with 37 observations and Group 2 (G2) with 47 observations, giving a total of 84 soil samples.\u003c/p\u003e\n\u003cp\u003eAccording to the data shown in Figure 6 and Table 1S, the two groups presented different characteristics in terms of elevation, chemical and physical attributes and pseudo-total content of heavy metals in the soil.\u003c/p\u003e\n\u003cp\u003eGroup 1 was characterized by the smallest number of samples (37), and was formed by soil samples located at the lowest point of the landscape, with a sandy loam texture and higher values for sand, silt, pH, P, Ca, Mg, Na and K, organic carbon, and the metals Zn, Pb, Cu and Mn (48.84, 276.08, 15.18 and 17.85 mg kg\u003csup\u003e-1\u003c/sup\u003e, respectively), probably due to the greater input of mineral and organic fertilizers in the area, reflecting the effect of the management practices.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe average P and K levels in the representative soils of G1 are worth highlighting, as they are up to six and three times greater, respectively, than those found in the soils of G2 (see Table 1S). According to Freire et al. (2013), these levels are classified as \u0026apos;very high\u0026apos; for P (\u0026gt;30 mg kg-1) and \u0026apos;high\u0026apos; for K (91\u0026ndash;135 mg kg-1), possibly due to the intense application of soluble phosphate and potassium fertilizers in these areas.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe areas in G1 had an average pH value in water of 5.69, a value that is very close to 5.5, considered ideal for hop cultivation (Sp\u0026oacute;sito et al., 2019). It should be noted that the average pH values (in water and KCl) in G1 show a negative charge balance, i.e. a negative ∆pH (∆pH = pH KCl 1 mol L-1 \u0026ndash; pH in water), indicating a predominance of negative charges in these soils and, therefore, a greater cation exchange capacity, which affords more favorable conditions for plant development, as can be seen in Table 3 and Figure 7b.\u003c/p\u003e\n\u003cp\u003eG2 grouped 47 samples, collected in areas with the highest elevation and the highest clay content (53%), with the soil texture classified as clayey.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eG2 presented higher values for CEC and the metals Fe, Al, Ni, Co, Cd and Cr compared to the soil samples from G1. This group also exhibited higher levels of organic matter and clay, both of which affect metal retention and the CEC. The lithology of the mountainous region of the state of Rio de Janeiro mostly comprises gneissic (44.4%) and granitic (24.6%) massifs, which give rise to acidic soils, with a diverse mineralogy dominated by clay minerals such as kaolinite, as well as oxides, hydroxides and oxyhydroxides of Fe, Al and Mn (Guimar\u0026atilde;es, 2020), which may also have favored the lithogenic enrichment of Cr, Co and Ni. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOver 50% of the soil samples from G2 exhibited more pronounced acidity (median = 5.17), which may be critical for crop development and possibly reflected in the poor shoot dry matter production (leaves + steams + cones) (Table 3 and Figure 7b).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFigure 7 and Tables 3, 2S and 3S show the set of standardized mean values and the descriptive analysis of the bioavailable metal content of the soil, the fresh and dry weight of the aerial part of the plantass, and the number of cones for each group (G1 and G2). In terms of metal bioavailability, figure 7a shows that G1 had the highest levels of Cr, Cu, Mn, Pb and Zn, while G2 had the highest levels of Cd and Ni, which, in general, favored increased accumulation of these elements by the plants. It should be noted that Pb and Ni showed no relationship between the bioavailable soil content and that accumulated in the plants.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll the results relating to the fresh and dry weight of aerial part of the plants (Figure 7b) were higher in the representative samples from G1. However, it was not possible to compare the number or fresh and dry weight of the cones, since the plants in G2 did not produce any cones, as shown in Table 3. This may have been due to the limitations of soil and terrain discussed above.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMean, median, minimum and maximum values for fresh and dry weight of the aerial part of the plantas (FAPW and DAPW) and cones (FCnW and FCnW), with the number (NCn) of cones for each group formed in the cluster analysis. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAs shown in Table 3, G1 had the highest values for fresh and dry shoot weight compared to G2. Rodolfi et al. (2021) found very similar values in a study conducted in Italy with the \u0026lsquo;Cascade\u0026rsquo; hop cultivar.\u003c/p\u003e\n\u003cp\u003eBased on the levels of each element in the leaves and steams of the plantas (Figure 7c and Table 2S), it can be seen that the samples from G1 exhibited higher average levels of P, Mg, Ca, Zn, Ni, Mn, Fe, Cu, Cr and Al, in the following order: Ca \u0026gt; Mg \u0026gt; K \u0026gt; P \u0026gt; Na \u0026gt; Al \u0026gt; Fe \u0026gt; Mn \u0026gt; Zn \u0026gt; Pb \u0026gt; Cu \u0026gt; Co \u0026gt; N \u0026gt; Cr. However, when analyzing the accumulated content (Figure 7d) of each element in the aerial part of the plant (leaves, steams and cones), only K showed different behavior to that seen with the accumulated elements, since the samples from G1 accumulated more K in the plants than did those from G2.\u003c/p\u003e\n\u003cp\u003eThe levels of Fe, Cu, Mn, Ni, Co, Cr, Cd, Pb, Zn, Al, Na, P, K, Ca and Mg in the cones (Table 4) showed significant variation, with the following order for the median values: Ca \u0026gt; Mg \u0026gt; P \u0026gt; Fe \u0026gt; Al \u0026gt; Zn \u0026gt; Mn \u0026gt; K \u0026gt; Cu \u0026gt; Pb \u0026gt; Na. Median levels of Ni, Co, Cr and Cd were not detected. Similar values for Cu (6.32 mg kg\u003csup\u003e-1\u003c/sup\u003e) and Cd (0.04 mg kg\u003csup\u003e-1\u003c/sup\u003e) were found by Liu (2019) when evaluating the heavy metal content of hops grown in China. However, the same research showed much higher values for Fe (772.55 mg kg\u003csup\u003e-1\u003c/sup\u003e) and Co (0.64 mg kg\u003csup\u003e-1\u003c/sup\u003e), and lower values for Al (119.06), K (2635) and Ca (1522.67) compared to the accumulated values in the cones from G1. Ni and Cr were detected in less than 20% of the cone samples. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4.\u0026nbsp;\u003c/strong\u003eMean, median, minimum and maximum values for the nutrient and heavy metal content in the cones from G1.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIt should be noted that, as per the National Health Surveillance Agency (ANVISA), there are no reference limits for the metal content of hops. However, metal concentrations in hops are insignificant when it comes to metals contaminating beer (Catelli, 2022), possibly due to the low, albeit essential, percentage contribution of hops to beer production (2%). Nevertheless, metal accumulation in the soil and plants should be monitored, since the use of mineral and organic fertilizers favors the accumulation of these elements, which can lead to a loss of environmental quality when cultivating hops.\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe average pseudo-total content for Fe (98.37 g kg\u003csup\u003e-1\u003c/sup\u003e) and Al (189.43 g kg\u003csup\u003e-1\u003c/sup\u003e) in G2 were more marked than those in G1 and may be closely linked to the chemical and physical characteristics of the soils in the region, which are predominantly made up of Cambisols, Argisols and Latosols (EMBRAPA, 2017). The relationship of the soil with the parent material is quite evident when the soil is formed in situ, i.e. directly on the parent material (Fadigas, 2002), resulting in more significant levels of Fe, Al, Ni, Co, Cd and Cr in G2, which were probably added to the soil naturally by weathering of the parent material, especially when formed by rocks rich in oxides and silicates (Oliveira et al., 2010). \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn terms of Cd, Figure 3 shows that approximately 30% of the samples analyzed exhibit contamination ranging from moderate (3\u0026lt;PI\u0026le;5) (7.1%) to severe (PI\u0026gt;5) (22.6%), indicating that, in addition to the lithogenic contribution in these areas, there was also an anthropogenic contribution, possibly associated with the type of management and the characteristics of the soil.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSousa et al. (2020) also saw severe Cd enrichment in areas of tomato-production in the mountainous region of Rio de Janeiro. Using principal component analysis (PCA), the authors found that PICd was closely related to the pseudo-total Al and Fe content, the elevation of the area, and, to a lesser extent, the K content. The authors conclude that any Cd remaining after the tomato harvest is predominantly associated with the levels of Fe and Al oxides, hydroxides and oxyhydroxides in the soil, i.e. is lithogenic in nature. However, the high PI values for cadmium may also reflect an anthropogenic contribution, as evidenced by the observed relationship with K, which suggests a possible contribution from potash and organic fertilizers (Sousa et al., 2020).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe results show that Cd remaining after the hop harvest is strongly related to the levels of Fe and Al oxides, hydroxides and oxyhydroxides in the clay fraction of the soil. However, the high level of Cd enrichment seen in certain areas reflects not only a lithogenic contribution, but also an anthropogenic contribution possibly linked to the use of organic fertilizers in these areas and to the higher clay and Corg content, which may have favored greater Cd retention.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe results indicate a significant effect from the terrain, a result of the transport and accumulation of metals at lower elevations. The greater elevation of the representative areas in G2 has a direct influence on the mobility of fertilizers and soil particles, which are easily washed away in mountainous areas (Franco et al., 2020; Sousa et al., 2020). According to Grisel and Assis (2015), the greater elevation and steeper slopes make it easier for smaller particles, such as clay, to be transported and accumulate in lower areas of the landscape. As a result, the natural fertility of the soil has decreased over the years, leading to an increased dependence on the use of fertilizers to restore the levels of soil fertility. The soils of G2 are therefore greatly influenced by the terrain, which possibly led to the removal of the surface horizons and exposure of the sub-surface horizons, as shown by the higher clay content in these areas.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAmaral Sobrinho et al. (1992) suggest the following typical ranges for heavy metals in phosphate fertilizers: 0.1-170 mg kg\u003csup\u003e-1\u003c/sup\u003e Cd, 7-225 mg kg\u003csup\u003e-1\u003c/sup\u003e Pb, 7-38 mg kg\u003csup\u003e-1\u003c/sup\u003e Ni, 1-300 mg kg\u003csup\u003e-1\u003c/sup\u003e Cu and 50-1450 mg kg\u003csup\u003e-1\u003c/sup\u003e Zn. Similar results were found by Campos et al. (2005), who evaluated the metal content of eight types of soluble phosphate fertilizer, with results that ranged from 4.2 to 115.0 mg kg\u003csup\u003e-1\u003c/sup\u003e for Cu, 17.0 to 234.0 mg kg\u003csup\u003e-1\u003c/sup\u003e for Pb, and 20.0 to 1013.0 mg kg\u003csup\u003e-1\u003c/sup\u003e for Zn. These results demonstrate the potential of phosphate fertilizers, which are widely used in the study area, to increase the levels of these metals in the soil, particularly Cu, Pb and Zn in the soils of G1.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eGon\u0026ccedil;alves et al. (2022) also found excessive use of phosphate fertilizers when analyzing soil samples from areas of kale-production in Petropolis in the mountainous region of Rio de Janeiro, where 70.5% of the samples had very high levels of P (\u0026gt; 30 mg kg\u003csup\u003e-1\u003c/sup\u003e).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eVery similar dynamics are seen for Mn, which also showed more pronounced values in G1. Mn oxides are generally more soluble than Fe and Al oxides, facilitating their dissolution and transport from higher to lower elevations. These results suggest a condition that favors metal bioavailability in the soil (Kumar et al., 2020a, 2021).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe better performance of the plants in G1 is possibly due to the chemical and physical attributes of the soil, as discussed above, and to the different types of management for some of the plants in G1, which are located at a lower elevation and receive a greater supply of organic and mineral inputs. Although these plants were in their first crop cycle, they come from a different genetic seedling bank to the plants in the other areas, which may have reflected in their superior productive performance. The median values for fresh cone weight (0.370 kg) were very similar to those reported by Fortuna (2021) for a conventional cultivation system in S\u0026atilde;o Paulo, Brazil, indicating good performance in terms of fresh cone production.\u003c/p\u003e\n\u003cp\u003eThe poorer development of the plants in G2, as shown by the lower values for fresh weight (Figure 7b and Table 3), is possibly due to the low soil pH (5.26) together with the exchangeable Al content of more than 0.30 cmol\u003csub\u003ec\u003c/sub\u003e kg\u003csup\u003e-1\u003c/sup\u003e presented by 32% of the samples in this group, which is toxic to plants and seen as a threshold for soil correction (Freire et al., 2013).\u003c/p\u003e\n\u003cp\u003eIt should be noted that the soil of G2 has a clayey texture (530.2 g kg\u003csup\u003e-1\u003c/sup\u003e), which may have hampered plant development. The textural class of soil best suited to hop cultivation is sandy loam, which has up to 18% clay. Higher levels are detrimental to the crop and can make it more difficult for the hops to establish and produce new roots (Stein, 2020).\u003c/p\u003e\n\u003cp\u003eThe metal content of the plants followed the enrichment pattern of the pseudo-total content and/or bioavailable content of the soils, where the Ca, Na, Co, Cr, Cu, Zn and Mg content was greater in the lower part of the landscape (G1), and the Cd content was greater in the higher areas (G2).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe median K concentration in the plant shoots was 8583.3 mg kg\u003csup\u003e-1\u003c/sup\u003e in G1 and 22820.0 mg kg\u003csup\u003e-1\u003c/sup\u003e in G2. Results very similar to those of G2 were found by Lafontaine et al. (2022) when evaluating the K content of different hop cultivars grown in the USA (mean value of 21630.40 mg kg\u003csup\u003e-1\u003c/sup\u003e) and Germany (mean value of 22906.29 mg kg\u003csup\u003e-1\u003c/sup\u003e). The high levels of both groups may be related to the high demand of the hops for this nutrient. K plays a key role in hop growth and controlling osmotic pressure, adjusting turgor, and controlling membrane polarization and protein biosynthesis (Chen et al., 2008), as well as significantly reducing the occurrence of pests and diseases (Ahmad et al., 2018). The K fertilizer (K\u003csub\u003e2\u003c/sub\u003eO) requirement for hops varies from 80 to 138 kg ha\u003csup\u003e-1\u003c/sup\u003e (Neve, 1991).\u003c/p\u003e\n\u003cp\u003eThe chemical analysis of the soil (Table 1S) indicated a high K content (91-135 mg kg\u003csup\u003e-1\u003c/sup\u003e) in the soil of G1 (0.29 cmol\u003csub\u003ec\u003c/sub\u003e dm\u003csup\u003e-3\u003c/sup\u003e, equivalent to 113.1 mg kg\u003csup\u003e-1\u003c/sup\u003e) and a low content (\u0026lt; 45 mg kg\u003csup\u003e-1\u003c/sup\u003e) in G2 (0.09 mg kg\u003csup\u003e-1\u003c/sup\u003e, equivalent to 35.1 mg kg\u003csup\u003e-1\u003c/sup\u003e) (Freire et al., 2017). The low K content in the soil of G2 is possibly due to the nutrient being extracted by the plants. This is evidenced by the soil being collected at the same time as the plants and therefore representing the residual content of the nutrient in the soil. Furthermore, as discussed above, these areas are greatly influenced by the terrain, favoring the loss of K, which is highly soluble, to the lower part of the landscape. However, the importance of potassium fertilization when growing hops should be highlighted, as potassium is a fundamental element, in high demand by the crop for its development.\u003c/p\u003e\n\u003cp\u003eAlthough the average K content of the plants (Table 2S) in G1 was lower (9637.3 mg kg\u003csup\u003e-1\u003c/sup\u003e) than in G2 (22820.0 mg kg\u003csup\u003e-1\u003c/sup\u003e), the accumulated content (25452.8 mg plant\u003csup\u003e-1\u003c/sup\u003e) was higher (Table 3S). This difference was possibly due to the dilution effect when assessing the total content of the plants, expressed in\u0026nbsp;mg kg\u003csup\u003e-1\u003c/sup\u003e. However, directly assessing K accumulation in the plants reflects the extraction potential of the plant in question, enabling more-refined fertilisation management.\u003c/p\u003e\n\u003cp\u003eNone of the plant samples exhibited high levels of either Cd or Pb. According to Young (1995), the levels commonly found for Cd and Pb in plants range from 0.2\u0026ndash;0.8 and 0.1\u0026ndash;10 mg kg\u003csup\u003e-1\u003c/sup\u003e, respectively. Levels ranging from 5 to 30 mg kg\u003csup\u003e-1\u003c/sup\u003e for Cd and from 30 to 300 mg kg\u003csup\u003e-1\u003c/sup\u003e for Pb are considered toxic. Therefore, based on these results, despite the accumulation of these metals being more pronounced in G2, there is no risk of the plants being contaminated by Cd or Pb.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe poor accumulation of some elements in the plants of both groups may reflect metal bioaccumulation in the roots, which did not favor translocation to the shoots or cones. However, it was not possible to collect the root system, as the plant is perennial and the research plan involved monitoring subsequent crop cycles at the same points.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eThe areas of hop-production showed no significant metal enrichment of the soils, except for Cd, which presented from moderate to severe contamination.\u003c/p\u003e\n\u003cp\u003eThe type of terrain and (experimental) soil management in the areas of hop-production are the main factors that contribute to the transfer and accumulation of metals in the plants as well as to their development.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis research offers unprecedented data on the behavior of hop cultivation in a mountainous agricultural area of Brazil, strengthening the knowledge base necessary to advance the tropicalization of hops, in addition to investigating the influence of different agricultural management practices on the quality of the soil and inflorescences of hops grown in a tropical region, generating scientific and technological insights to improve production systems.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eFunding \u003c/p\u003e\n\u003cp\u003eSpecial thanks to Coordena\u0026ccedil;\u0026atilde;o de Aperfei\u0026ccedil;oamento de Pessoal de N\u0026iacute;vel Superior and Funda\u0026ccedil;\u0026atilde;o Carlos Chagas Filho de Amparo \u0026agrave; Pesquisa do Estado do Rio de Janeiro for the financial support.\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank Grupo Petr\u0026oacute;polis for providing the experimental area for this research, as well as all the logistical and labor support for the maintenance of the area and team activities.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/em\u003e\u003c/p\u003e\n\n\u003cp\u003eCompeting Interest\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eThe authors have no relevant financial or non-financial interests to disclose\u003c/em\u003e.\u003c/p\u003e\n\n\u003cp\u003eAuthor Contributions\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAll authors contributed to the study conception and design. The first draft of the manuscript was written by Mariana Ferreira Santa Cruz Coimbra and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/em\u003e\u003c/p\u003e\n\n\u003cp\u003eData Availability\u003c/p\u003e\n\u003cp\u003eThe datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAhmad, Z., Anjum, S.,Waraich, E.A., Ayub, M.M., Mhmad, T., Tariq, R.M.S., Ahmad, R., Iqbal, M.A., 2018. Growth, Physiology, and Biochemical Activities of Plant Responses with Foliar Potassium Application under Drought Stress. Journal of Plant Nutrition. 41, pp. 1734\u0026ndash;1743. https://doi.org/10.1080/01904167.2018.1459688\u003c/li\u003e\n\u003cli\u003eAkter, M., Kabir, M. H., Alam, M. A, Al Mashuk, K., Rahman, M.M., Alam, M.S, Brodie, G., Isl\u0026atilde;, S. M. M., Gaihre, Y. K, Rahman, GKMM. 2023. Geospatial Visualization and Ecological Risk Assessment of Heavy Metals in Rice Soil of a Newly Developed Industrial Zone in Bangladesh. 15. https://doi.org/10.3390/su15097208\u003c/li\u003e\n\u003cli\u003eAli, H., \u0026amp; Khan, E., 2019. Trophic transfer, bioaccumulation, and biomagnification of non-essential hazardous heavy metals and metalloids in food chains/webs\u0026mdash;Concepts and implications for wildlife and human health. Human and Ecological Risk Assessment: An International Journal, 25 (6), pp. 1353-1376.\u003c/li\u003e\n\u003cli\u003eAlmaguer, C., Sch\u0026ouml;nberger, C., Gastl, M., Arendt, E. K., Becker, T., 2014. \u003cem\u003eHumulus lupulus\u003c/em\u003e \u0026ndash; a story that begs to be told. Journal of the Institute of Brewing, v. 120, n. 4, pp. 289-314. https://doi.org/10.1002/jib.160\u003c/li\u003e\n\u003cli\u003eAlonso Esteban, J. I., Pinela, J., Barros, L., Ćirić, A., Soković, M., Calhelha, R. C., Torija-Isasa, E., S\u0026aacute;nchez Mata, M. C., Ferreira, I. C. F. R., 2019. Phenolic composition and antioxidant, antimicrobial and cytotoxic properties of hop (\u003cem\u003eHumulus lupulus\u003c/em\u003e L.) seeds. Industrial Crops \u0026amp; Products, 134, 154-159. https://doi.org/10.1016/j.indcrop.2019.04.001\u003c/li\u003e\n\u003cli\u003eAmaral Sobrinho, N.M.B., Costa, L.M., Oliveira, C., Velloso, A.C.X., 1992. Metais pesados em alguns fertilizantes e corretivos. Revista Brasileira de Ci\u0026ecirc;ncia do Solo, v.16, pp. 271276.\u003c/li\u003e\n\u003cli\u003eANVISA, 2023. Ag\u0026ecirc;ncia Nacional de Vigil\u0026acirc;ncia Sanit\u0026aacute;ria \u0026ndash; \u0026Oacute;rg\u0026atilde;o do Governo. Dispon\u0026iacute;vel em: https://www.gov.br/anvisa/pt-br (accessed 01 march 2024).\u003c/li\u003e\n\u003cli\u003eAquino, A. M. D., Teixeira, A. J., Fonseca, M. J. de O., Assis, R. L. D., Ozassa, T. I. \u0026quot;Produ\u0026ccedil;\u0026atilde;o de l\u0026uacute;pulo na Regi\u0026atilde;o Serrana Fluminense: manual de boas pr\u0026aacute;ticas.\u0026quot;, 2022. Associa\u0026ccedil;\u0026atilde;o Comercial, Industrial e Agr\u0026iacute;cola de Nova Friburgo \u0026ndash; ACIANF. http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/1144201. (accessed 01 january 2024).\u003c/li\u003e\n\u003cli\u003eBarker, A.V., Pilbeam, D. J.. Handbook of Plant Nutrition; \u003cem\u003eHandbook of Plant Nutritioneds\u003c/em\u003e; CRC Press: Boca Raton, FL, USA, 2015. https://doi.org/10.21273/hortsci.42.2.422b\u003c/li\u003e\n\u003cli\u003eBiendl, M., 2009. Hops and health. Technical Quarterly. https://doi.org/10.1094/tq-46-2-0416-01\u003c/li\u003e\n\u003cli\u003eBocquet, L., Sahpaz S., Hilbert J. L., Rambaud C., Rivi\u0026egrave;re C., 2018. \u003cem\u003eHumulus lupulus\u003c/em\u003e L., a very popular beer ingredient and medicinal plant: overview of its phytochemistry, its bioactivity, and its biotechnology. Phytochemistry Reviews. https://doi.org/10.1007/s11101-018-9584-y\u003c/li\u003e\n\u003cli\u003eBrasil, 2023. Minist\u0026eacute;rio da Agricultura e Pecu\u0026aacute;ria. Anu\u0026aacute;rio da Cerveja 2022 / Minist\u0026eacute;rio da Agricultura e Pecu\u0026aacute;ria. Secretaria de Defesa Agropecu\u0026aacute;ria. \u0026ndash; Bras\u0026iacute;lia: MAPA/DAS. https://www.gov.br/agricultura/pt-br/assuntos/inspecao/produtos-vegetal/publicacoes/anuario-da-cerveja-2022/view. (accessed 01 march 2024).\u003c/li\u003e\n\u003cli\u003eCampos, M. L., Silva, F. N. D. A., Furtini NETO, A. E., Guilherme, L. R. G., Marques, J. J., Antunes, A. S., 2005. Determina\u0026ccedil;\u0026atilde;o de c\u0026aacute;dmio, cobre, cromo, n\u0026iacute;quel, chumbo e zinco em fosfatos de rocha. Pesquisa Agropecu\u0026aacute;ria Brasileira, 40 (4), pp. 361 - 367. https://doi.org/10.1590/S0100-204X2005000400007\u003c/li\u003e\n\u003cli\u003eCatelli, E. G., 2022. An\u0026aacute;lise da presen\u0026ccedil;a de metais em cervejas artesanais e comercializadas no Paran\u0026aacute; (Disserta\u0026ccedil;\u0026atilde;o de bacharelado, Universidade Tecnol\u0026oacute;gica Federal do Paran\u0026aacute;). https://portaldeinformacao.utfpr.edu.br/Record/riut-1-30984/Details (accessed 01 february 2024).\u003c/li\u003e\n\u003cli\u003eChen, Y.-F., Wang, Y., Wu, W.-H, 2008. Membrane Transporters for Nitrogen, Phosphate and Potassium Uptake in Plants. Journal of Integrative Plant Biology, 50, 835 - 848. https://doi.org/ 10.1111/j.1744-7909.2008.00707.x \u003c/li\u003e\n\u003cli\u003eDurello, R. S., Silva, L. M., Bogusz J. R. S., 2019. Qu\u0026iacute;mica do l\u0026uacute;pulo. Qu\u0026iacute;mica Nova, S\u0026atilde;o Paulo, 42 (8), pp. 900-919. https://www.scielo.br/pdf/qn/v42n8/0100-4042-qn-42-08-0900.pdf (accessed 02 april 2024).\u003c/li\u003e\n\u003cli\u003eFadigas, F. D. S., Amaral-Sobrinho, N. M. B. D., Mazur, N., Anjos, L. H. C. D., \u0026amp; Freixo, A. A. (2002). Concentra\u0026ccedil;\u0026otilde;es naturais de metais pesados em algumas classes de solos brasileiros. Bragantia, 61, pp. 151-159. https://doi.org/10.1590/S0006-87052002000200008\u003c/li\u003e\n\u003cli\u003eFAO \u0026ndash; Food and Agriculture Organization, 2024. https://www.fao.org/land-water/land/en/ (accessed 07 april 2024).\u003c/li\u003e\n\u003cli\u003eFortuna, G. C., Gomes, J. A. D. O., Campos, O. P., Neves, C. S., \u0026amp; Bonfim, F. P. G. (2023). Desempenho agron\u0026ocirc;mico de variedades de \u003cem\u003eHumulus lupulus\u003c/em\u003e L. cultivadas em sistema org\u0026acirc;nico e convencional no centro-oeste paulista, Brasil. Ci\u0026ecirc;ncia Rural, 53. https://doi.org/10.1590/0103-8478cr20210704\u003c/li\u003e\n\u003cli\u003eFranco, T. F., Lima, E. S. A., Amaral Sobrinho, N. M. B., Carmo, M. G. F., Breda, F. A. F., 2020. Enrichment and bioavailability of toxic lements in intensive vegetable production areas. Revista Caatinga. 33, pp. 124 \u0026ndash; 134. https://doi.org/10.1590/1983-21252020v33n114rc\u003c/li\u003e\n\u003cli\u003eFreire, L. R., Balieiro, F. C., Zonta, E., Anjos, L. H. C, Pereira, M. G, Lima, E., Guerra, J. G. M., e Ferreira, M. B. C., 2013. Manual de calagem e aduba\u0026ccedil;\u0026atilde;o do estado do Rio de Janeiro\u003cem\u003e. \u003c/em\u003eEDUR. https://www.embrapa.br/busca-de-publicacoes/-/publicacao/963089/manual-de-calagem-e-adubacao-do-estado-do-rio-de-janeiro. (accessed 02 march 2024).\u003c/li\u003e\n\u003cli\u003eFreitas, C. F. Grupo Petr\u0026oacute;polis inicia vendas de l\u0026uacute;pulo brasileiro em pellets e mira em microcervejarias. Catalisi. \u003c/li\u003e\n\u003cli\u003ehttps://catalisi.com.br/grupo-petropolis-inicia-vendas-de-lupulo-brasileiro-em-pellets-e-mira-em-microcervejarias/ (accessed 18 january 2024).\u003c/li\u003e\n\u003cli\u003eFruszecka-Kosowska, A., Baran, A., Wdowin, M., Mazur-Kajta, K., Czech, T., 2020. The contents of the potentially harmful elements in the arable soils of southern Poland, with the assessment of ecological and health risks: a case study. \u003cem\u003eEnvironmental Geochem Health\u003c/em\u003e 42, https://doi.org/10.1007/s10653-019-00372-w\u003c/li\u003e\n\u003cli\u003eGingrich, G.; Hart, J.; Christensen, N. Hops; Oregon State University, Extension Service: Corvallis, OR, USA, 1994. https://ir.library.oregonstate.edu/concern/administrative_report_or_publications/0g354f82t (accessed 01 february 2025).\u003c/li\u003e\n\u003cli\u003eGrisel, P. N. e Assis, R. N., 2015. Din\u0026acirc;mica agr\u0026aacute;ria da Regi\u0026atilde;o Sudoeste do munic\u0026iacute;pio de Nova Friburgo e os atuais desafios de sua produ\u0026ccedil;\u0026atilde;o hort\u0026iacute;cola familiar. Documentos n\u0026ordm; 299, Embrapa Agrobiologia, Serop\u0026eacute;dica.\u003c/li\u003e\n\u003cli\u003ehttp://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/1015689. (accessed 15 march 2024).\u003c/li\u003e\n\u003cli\u003eGon\u0026ccedil;alves, R. G. M., Santos, C. A., Breda, F. A. F., Lima, E. S. A. L., Carmo, M. G. F., Souza, C. C. B., Amaral Sobrinho, N. M. B., 2022. Cadmium and lead transfer factors to kale plants (Brassica oleracea var. acephala) grown in mountain agroecosystem and its risk to human health. Environmental monitoring and assessment, 194, 366. https://doi.org/10.1007/s10661-022-10035-6\u003c/li\u003e\n\u003cli\u003eJia, Y., Wang, L., Qu, Z., Yang, Z., 2018. Distribution, contamination and accumulation of heavy metals in water, sediments, and freshwater shellfish from Liuyang River, Southern China. Environmental Science and Pollution Research, 25(7), pp. 7012-7020.\u003c/li\u003e\n\u003cli\u003eJiang, C. H., Sun, T. L., Xiang, D. X., Wei, S. S., Li, W. Q., 2018. Anticancer activity and mechanism of xanthohumol: a prenylated flavonoid from hops (\u003cem\u003eHumulus \u003c/em\u003elupulus L.). Frontiers in Pharmacology, v. 9, n. 530, pp. 1-13. https://doi.org/10.3389/fphar.2018.00530\u003c/li\u003e\n\u003cli\u003eJohnsen, I. V., Aaneby, J., 2019. Soil intake in ruminants grazing on heavy-metal contaminated shooting ranges. Science of the Total Environment687, pp. 41\u0026ndash;49. https://doi.org/10.1016/j.scitotenv.2019.06.086\u003c/li\u003e\n\u003cli\u003eKabata-Pendias, A., 2011. Trace Elements in Soils and Plants. CRC Press, Taylor and Francis Group. Boca Raton. https://doi.org/10.1201/b10158\u003c/li\u003e\n\u003cli\u003eKhan, S., Cao, Q., Zheng, Y. M., Huang, Y. Z., Zhu, Y. G., 2008. Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China. Environmental Pollution 152, 686\u0026ndash;692. https://doi.org/10.1016/j.envpol.2007.06.056\u003c/li\u003e\n\u003cli\u003eKumar, A., Tripti, Raj, D., Maiti, S. K., Maleva, M., Borisova, G., 2022. Soil Pollution and Plant Efficiency Indices for Phytoremediation of Heavy Metal(loid)s: Two-Decade Study (2002\u0026ndash;2021). Metals (Basel). https://doi.org/10.3390/met12081330\u003c/li\u003e\n\u003cli\u003eLafontaine, S., Thomson, D., Schubert, C., M\u0026uuml;ller, I., Kyle, M., Biendl, M., \u0026amp; Rettberg, N., 2022. How deviations in the elemental profile of \u003cem\u003eHumulus lupulus\u003c/em\u003e grown throughout the US and Germany influence hop and beer quality. \u003cem\u003eFood chemistry\u003c/em\u003e, 395, 133543. https://doi.org/10.1016/j.foodchem.2022.133543\u003c/li\u003e\n\u003cli\u003eLima, E.S.A., Matos. T de S., Pinheiro, H. S. K., Guimar\u0026atilde;es, L. D. D., P\u0026eacute;rez, D. V., Amaral Sobrinho, N. M. B., 2018. Soil heavy metal content on the hillslope region of Rio de Janeiro, Brazil: reference values. Environmental monitoring and assessment, 190, n\u0026ordm; 6, pp. 1-11. https://doi.org/10.1007/s10661-018-6736-x\u003c/li\u003e\n\u003cli\u003eLiu, Z., Waang, Y., e Liu, Y., 2019. Geographical origins and varieties identification of hops (\u003cem\u003eHumulus lupulus\u003c/em\u003e L.) by multi-metal elements fingerprinting and the relationships with functional ingredients. Food Chemistry, 289, 522\u0026ndash;530. https://doi.org/10.1016/j.foodchem.2019.03.099\u003c/li\u003e\n\u003cli\u003eNeve, R.A., 1991. Hops, Chapman and Hall: London, UK.\u003c/li\u003e\n\u003cli\u003eOliveira, L. F. C., Lemke-de-Castro, M. L., Rodrigues, C., Borges, J. D., 2010. Isotermas de sor\u0026ccedil;\u0026atilde;o de metais pesados em solos do cerrado de Goi\u0026aacute;s. Revista Brasileira de Engenharia Agr\u0026iacute;cola e Ambiental, v. 14, n. 7, pp. 776-782. https://doi.org/10.1590/s1415-43662010000700014\u003c/li\u003e\n\u003cli\u003eSarmento, R. R., 2017. Fracionamento Geoqu\u0026iacute;mico de Zn, Ni e Cd em Solos da Regi\u0026atilde;o Serrana \u0026ndash; RJ: Valores de Refer\u0026ecirc;ncia de Biodisponibilidade e Avalia\u0026ccedil;\u0026atilde;o da Contamina\u0026ccedil;\u0026atilde;o em \u0026Aacute;reas Cultivadas com Hortali\u0026ccedil;as de Folha.\u003c/li\u003e\n\u003cli\u003ehttps://rima.ufrrj.br/jspui/handle/20.500.14407/15825. (accessed 15 March 2024).\u003c/li\u003e\n\u003cli\u003eSiqueira, J. H., Santana, N. M. T., Pereira, T. S. S., Moreira, A. D., Bense\u0026ntilde;or, I. M., Barreto, S. M. e Molina, M. D. C. B., 2021. Consumo de bebidas alco\u0026oacute;licas e n\u0026atilde;o alco\u0026oacute;licas: Resultados do ELSA-Brasil. Ci\u0026ecirc;ncia \u0026amp; Sa\u0026uacute;de Coletiva, 26, 3825-3837. https://doi.org/10.1590/1413-81232021269.2.30682019\u003c/li\u003e\n\u003cli\u003eSp\u0026oacute;sito, M. B, Ismael, R. V., Barbosa, C. M. A., Tagliaferro, A. L., 2019. A cultura do l\u0026uacute;pulo. Piracicaba, SP: Esalq - Divis\u0026atilde;o de Biblioteca, pp. 81. (S\u0026eacute;rie Produtor Rural, 68). https://www.researchgate.net/profile/Caio-Morais-De-Alcantara-Barbosa/publication/334672293_A_Cultura_do_Lupulo/links/5d3dcb5a299bf1995b524c08/A-Cultura-do-Lupulo.pdf (accessed 15 January 2024).\u003c/li\u003e\n\u003cli\u003eStein, A. J. K., 2020. L\u0026uacute;pulo do Brasil: Introdu\u0026ccedil;\u0026atilde;o ao cultivo e manejo. (SteinHops - L\u0026uacute;pulo do Brasil), 2020, pp. 18. Kindle Edition.\u003c/li\u003e\n\u003cli\u003eTeixeira P. C., Donagemma G. K., Fontana A., Teixeira W. G., 2017. EMBRAPA - Empresa Brasileira de Pesquisa Agropecu\u0026aacute;ria. Manual de m\u0026eacute;todos de an\u0026aacute;lise de solo. Ed. Bras\u0026iacute;lia, DF: Embrapa. pp. 574.\u003c/li\u003e\n\u003cli\u003eTeixeira, A. J.; Aquino, A. M. de; Macedo, J. R. de, 2022. EMBRAPA. Recomenda\u0026ccedil;\u0026otilde;es preliminares de calagem e aduba\u0026ccedil;\u0026atilde;o para a cultura do l\u0026uacute;pulo. https://www.embrapa.br/busca-de-publicacoes/-/publicacao/1144211/recomendacoes-preliminares-de-calagem-e-adubacao-para-a-cultura-do-lupulo?utm_source. (accessed 17 june 2025).\u003c/li\u003e\n\u003cli\u003eUSEPA., 1996. Digest\u0026atilde;o \u0026aacute;cida de sedimentos, lamas e solos - m\u0026eacute;todo EPA 3050B. Ag\u0026ecirc;ncia de Prote\u0026ccedil;\u0026atilde;o Ambiental dos Estados Unidos., https://www.epa.gov/sites/production/fles/2015-06/documents/epa-3050b.pdf. (accessed 15 january 2025).\u003c/li\u003e\n\u003cli\u003eUSEPA., 2008. Extra\u0026ccedil;\u0026atilde;o \u0026aacute;cida de sedimentos, lodos e solos - m\u0026eacute;todo EPA 3050. Ag\u0026ecirc;ncia de Prote\u0026ccedil;\u0026atilde;o Ambiental dos Estados Unidos. http://www.epa.gov/waste/hazard/testmethods. (accessed 15 january 2025).\u003c/li\u003e\n\u003cli\u003eWu, S., Peng, S., Zhang, X., Wu, D., Luo, W., Zhang, T., Wu, L., 2015. Levels and health risk assessments of heavy metals in urban soils in Dongguan, China. Journal of Geochemical Exploration, 148, pp. 71-78. https://doi.org/10.1016/j.gexplo.2014.08.009\u003c/li\u003e\n\u003cli\u003eZoffoli, H. J. O., Do Amaral-Sobrinho, N. M. B., Zonta, E., Luisi, M. V., Marcon, G., Tol\u0026oacute;n Becerra, A., 2013. Inputs of heavy metals due to agrochemical use in tobacco fields in Brazil\u0026rsquo;s Southern Region. Environ Monit Assess 185, 2423\u0026ndash;2437. https://doi.org/10.1007/s10661-012-2721-y\u003c/li\u003e\n\u003cli\u003eYoung, S., 1995. Toxic metals in soil-plant systems. The Journal of Agricultural Science\u003cem\u003e.\u003c/em\u003e https://doi.org/10.1017/s0021859600071422\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 1\u0026nbsp;\u003c/strong\u003eSet up, altitude and area of hop-production Areas 1, 2, 3 and 4 in Teres\u0026oacute;polis in the mountainous region of Rio de Janeiro.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003eSet up period (semester)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 25px;\"\u003e\n \u003cp\u003eAltitude (m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 21px;\"\u003e\n \u003cp\u003eArea (ha)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003eArea 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e820\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003e0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003eArea 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e848 - 856\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003e1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003eArea 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e856 - 923\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003e0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003eArea 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 31px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003e828\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 21px;\"\u003e\n \u003cp\u003e0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"93%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 2\u0026nbsp;\u003c/strong\u003eAverage levels of heavy metals present in the mineral fertilizers and organic manure (chicken litter) used in the study area.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003eElement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003eMineral Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003eOrganic Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 76px;\"\u003e\n \u003cp\u003e------------------------------- mg kg\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003ecp\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003e------------------------------\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003eCd\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003e1.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003e0.55\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003eCo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003e1,72\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003eCr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003e2.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003e8.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003eCu\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003e2.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003e249.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003e7.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003e365.14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003eNi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003e0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003e3.87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003ePb\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003e15.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003e4.56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 23px;\"\u003e\n \u003cp\u003eZn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 43px;\"\u003e\n \u003cp\u003e3.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 32px;\"\u003e\n \u003cp\u003e298.20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"3\" valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003ecp \u0026ndash; comercial product; ND \u0026ndash; not detectable.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"9\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 3\u0026nbsp;\u003c/strong\u003eMean, median, minimum and maximum values for fresh and dry weight of the aerial part of the plantas (FAPW and DAPW) and cones (FCnW and FCnW), with the number (NCn) of cones for each group formed in the cluster analysis.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"4\"\u003e\n \u003cp\u003e------------------------G1---------------------\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\"\u003e\n \u003cp\u003e----------------------G2------------------\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMinimum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMaximum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMinimum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMaximum\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eFAP\u0026nbsp;(kg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e2.51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eDAPW (kg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eNCn (unit)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1141.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e500.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e28.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3100.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eFCnW (kg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eFCnW (kg)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eND = not detectable.\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 4\u0026nbsp;\u003c/strong\u003eMean, median, minimum and maximum values for the nutrient and heavy metal content in the cones from G1.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd colspan=\"4\"\u003e\n \u003cp\u003e----------------------------------G1----------------------------------\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMedian\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMinimum\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eMaximum\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eAlCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e227.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e177.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e35.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e519.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCdCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCoCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCrCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCuCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12.20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eFeCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e233.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e219.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e131.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e407.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMnCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e36.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e33.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e24.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e58.07\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eNiCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e10.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ePbCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eND\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e7.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eZnCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e45.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e43.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e33.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e89.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCaCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e18177.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e16497.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e11832.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e28708.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMgCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e6295.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e5745.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e3726.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12158.88\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eNaCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e400.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0.72\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eKCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e22350.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e21.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e18.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e30.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ePCn (mg kg\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e325.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e290.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e155.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e533.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eND = not detectable.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\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":"environmental monitoring, soil quality, soil pollution, Humulus lupulus L.","lastPublishedDoi":"10.21203/rs.3.rs-7285459/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7285459/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The aim of this study was to evaluate heavy metal contamination in an area of Humulus lupulus L. production, as well as to identify the main factors that help enrich the soil and plants with these elements. The study was conducted in one of the largest hop-producing properties in Brazil, located in a mountain agroecosystem. Samples of soil and plant tissue were collected at 42 points throughout the study area. Soil fertility and particle size were analyzed, in addition to determining the levels of heavy metals in the samples using acid digestion, as per EPA methods 3050 and 3050B. This was followed by atomic absorption spectrometry. The Pollution Index (PI) was then calculated, based on the results. The relationship between the variables was investigated using principal component analysis (PCA) and cluster analysis. Cadmium (Cd) was the only element that showed moderate to severe enrichment in the soil. The terrain, parent material and management practices adopted on the property had a significant influence on the enrichment of metals in both the soil and the plants, as well as impacting hop productivity. These factors were therefore mainly responsible for the transfer and accumulation of metals in the plants. Despite this, the levels of metals detected in hop inflorescences show no risk of being transferred to derivative products, such as beer.","manuscriptTitle":"Factors Influencing the Development and Accumulation of Heavy Metals in Hop Plants Grown in Tropical Regions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-06 14:24:52","doi":"10.21203/rs.3.rs-7285459/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":"8dc82cf8-8c6e-4e90-9b26-ba7671221462","owner":[],"postedDate":"August 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-08-25T15:58:41+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-06 14:24:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7285459","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7285459","identity":"rs-7285459","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}