Changes in biochemical components of wheat and rapeseed grown on selenium-contaminated soil (original) (raw)
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Selenium in the Soil-Plant Environment: A Review
International Journal of Applied Agricultural Sciences
Selenium (Se) exhibits a "double-edged" behavior in animal and human nutrition. It is a micronutrient required in low concentrations by animals and humans, but toxic at high concentrations. Selenium deficiency has been associated with cancer and other health problems. Selenium requirements are commonly met through soils and plants such as wheat, rice, vegetables and maize in many countries. Selenium concentration in the soil generally ranges from 0.01-2.0 mg kg-1 but seleniferous soils usually contain more than 5 mg kg-1. Seleniferous soils have been reported in Ireland, China, India and USA. Weathering of parent rocks and atmospheric deposition of volcanic plumes are natural processes increasing Se levels in the environment. Anthropogenic sources of Se include irrigation, fertilizer use, sewage sludge and farmyard manure applications, coal combustion and crude oil processing, mining, smelting and waste incineration. Mobility of Se in the soil-plant system largely depends on its speciation and bioavailability in soil which is controlled by pH and redox potential. Plant uptake of Se varies with plant species and Se bioavailability in the soil. The uptake, translocation, transformation, metabolism, and functions of Se within the plant are further discussed in the paper. The release of Se in soils and subsequent uptake by plants has implications for meeting Se requirements in animals and humans.
The plants grown in seleniferous soils constitute a major source of toxic selenium levels in the food chain of animals and human beings. Greenhouse and field experiments were conducted to study selenium concentrations of weeds, forages and cereals grown on seleniferous soils located between 31.0417°to 31.2175°N and 76.1363°to 76.4147°E in northwestern India. Eleven winter season (November-April) weed plants were grown in the greenhouse in a soil treated with different levels of selenate-Se. Selenium concentrations of weed plants increased progressively with the levels of selenate-Se in soil. The highest Se concentration was recorded by Silene gallica (246 mgkg − 1 ) and the lowest by Avena ludoviciana (47 mgkg − 1 ) at 2.5 mg Sekg − 1 soil. A. ludoviciana and Spergula arvensis proved highly tolerant to the presence of 1.25 and 2.5 mg selenate-Sekg − 1 soil and the remaining weeds were sensitive to Se. Dry matter yield of Se-sensitive weed plants was 25 to 62% of the yield in the no-Se control at 1.25 mg selenate-Sekg − 1 and 6 to 40% at 2.5 mg selenate-Se kg − 1 soil. Other symptoms like change in leaf colour and size, burning of leaf tips and margins, and delayed flowering were also observed due to Se. Dry matter yield of Se-sensitive weed plants expressed as percentage of yield in the no-Se control at both the Se levels was inversely correlated with their Se content (r = −0.731, p b 0.01, N = 17). Among the weed plants grown in seleniferous soils under field situations, Mentha longifolia accumulated the highest Se (365 mgkg − 1 ) and Phalaris minor the lowest (34 mgkg − 1 ). Among agricultural crops grown on a naturally contaminated soil in the greenhouse, Se concentrations were the highest for oilseed crops (19-29 mg kg − 1 ), followed by legumes (6-13 mg kg − 1 ) and cereals (2-18 mg kg − 1 ). Helianthus annuus among the oilseed crops, A. ludoviciana among the winter season weeds, M. longifolia among the summer season (May-October) weeds and Cirsium arvense among the perennial weeds can be used for phytoremediation of seleniferous soils as these accumulate the highest amounts of Se.
Science of The Total Environment, 2009
The plants grown in seleniferous soils constitute a major source of toxic selenium levels in the food chain of animals and human beings. Greenhouse and field experiments were conducted to study selenium concentrations of weeds, forages and cereals grown on seleniferous soils located between 31.0417°to 31.2175°N and 76.1363°to 76.4147°E in northwestern India. Eleven winter season (November-April) weed plants were grown in the greenhouse in a soil treated with different levels of selenate-Se. Selenium concentrations of weed plants increased progressively with the levels of selenate-Se in soil. The highest Se concentration was recorded by Silene gallica (246 mgkg − 1 ) and the lowest by Avena ludoviciana (47 mgkg − 1 ) at 2.5 mg Sekg − 1 soil. A. ludoviciana and Spergula arvensis proved highly tolerant to the presence of 1.25 and 2.5 mg selenate-Sekg − 1 soil and the remaining weeds were sensitive to Se. Dry matter yield of Se-sensitive weed plants was 25 to 62% of the yield in the no-Se control at 1.25 mg selenate-Sekg − 1 and 6 to 40% at 2.5 mg selenate-Se kg − 1 soil. Other symptoms like change in leaf colour and size, burning of leaf tips and margins, and delayed flowering were also observed due to Se. Dry matter yield of Se-sensitive weed plants expressed as percentage of yield in the no-Se control at both the Se levels was inversely correlated with their Se content (r = −0.731, p b 0.01, N = 17). Among the weed plants grown in seleniferous soils under field situations, Mentha longifolia accumulated the highest Se (365 mgkg − 1 ) and Phalaris minor the lowest (34 mgkg − 1 ). Among agricultural crops grown on a naturally contaminated soil in the greenhouse, Se concentrations were the highest for oilseed crops (19-29 mg kg − 1 ), followed by legumes (6-13 mg kg − 1 ) and cereals (2-18 mg kg − 1 ). Helianthus annuus among the oilseed crops, A. ludoviciana among the winter season weeds, M. longifolia among the summer season (May-October) weeds and Cirsium arvense among the perennial weeds can be used for phytoremediation of seleniferous soils as these accumulate the highest amounts of Se.
Plant and Soil, 2005
Critical levels of selenium in raya (Brassica juncea Czern L.), maize (Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were worked out by growing these crops in an alkaline silty loam soil treated with different levels of selenite-Se ranging from 1 to 25 lg g )1 soil. Significant decrease in dry matter yield was observed above a level of 5 lg Se g )1 soil in raya and maize; 4 lg Se g )1 soil in wheat and 10 lg Se g )1 soil in rice shoots. The critical level of Se in plants above which significant decrease in yield would occur was found to be 104.8 lg g )1 in raya, 76.9 lg g )1 in maize, 41.5 lg g )1 in rice and 18.9 lg g )1 in wheat shoots. Significant coefficients of correlation were observed between Se content above the critical level and dry matter yield of raya as well as rice (r = )0.99, P £ 0.01), wheat (r = )0.97, P £ 0.01) and maize ((r = )0.96, P £ 0.01). A synergistic relationship was observed between S and Se content of raya (r = 0.96, P £ 0.01), wheat (r = 0.89, P £ 0.01), rice (r = 0.85, P £ 0.01) and maize (r = 0.84, P £ 0.01). Raya, maize and rice absorbed Se in levels toxic for animal consumption (i.e. >5 mg Se kg )1 ) when the soil was treated with more than 1.5 lg Se g )1 . In case of wheat, application of Se more than 3 lg g )1 soil resulted in production of toxic plants.
Frontiers of Agriculture in China, 2009
A greenhouse experiment was conducted to study the accumulation of selenium by some vegetable crops commonly grown in the Indian Punjab. Eleven vegetable crops were raised in an alkaline clay loam soil treated with different levels of selenate-Se, i.e., 0, 1.25, 2.5 and 5.0 mg·kg−1 soil. Dry matter yield of both edible and inedible portions of different vegetable crops decreased with increasing Se level in soil except potato (Solanum tuberosum), radish (Raphanus sativus) and cauliflower (Brassica oleracea var. botrytis) which recorded 10%–21% increase in inedible dry matter at 1.25 mg·kg−1 Se soil. Application of 5 mg·kg−1 selenate-Se soil resulted in complete mortality in the case of radish, turnip (Brassica rapa) and brinjal (Solanum melongena). Some vegetable crops including tomato (Lycopersicum esculentum), cauliflower and pea (Pisum sativum), though, survived the toxic effect at the highest concentration of Se yet did not bear any fruit. Potato and spinach (Spinacea oleracea) proved to be highly tolerant crops. Selenium concentration in the edible as well as inedible portions of all the vegetables increased with an increase in the level of applied Se. Selenium accumulation in the edible portion of vegetable crops in the no-Se control ranged from 2.2 to 4.9 mg·kg−1 Se dry weight. At 1.25 mg·kg−1 Se soil, the edible portion of radish accumulated the greatest concentration of Se (38 mg·kg−1 Se dry weight) with that of onion (Allium cepa) bulb the lowest (9 mg·kg−1 Se dry weight). Inedible portions of vegetables accumulated Se 2–5 times more than that absorbed by edible portions. Total Se uptake by edible portions of different vegetables was the greatest at 1.25 mg·kg−1 Se soil, ranging from 7 to 485 μg·pot−1. The results suggest that vegetable crops vary in their sensitivity to the presence of selenate-Se in soil. Vegetative portions were several times richer in Se than other parts of vegetable crops.
Distribution and bioavailability of selenium fractions in some seleniferous soils of Punjab, India
Archives of Agronomy and Soil Science, 2005
Soil-solid phase associations of Se in seleniferous soils of Punjab were investigated by following sequential extraction procedures involving multiple extractions with 0.2 M K 2 SO 4 (2 times), 0.1 M Na 2 SeO 3 (4 times), 0.05 M NH 4 OH (4 times), 6 M HCl (2 times) and 9 M HNO 3 (2 times) vis-a-vis single extractions with 0.25 M KCl, 0.1 M KH 2 PO 4 , 4 M HCl and concentrated HCl. Soil samples were equilibrated with 75 Se (as Na 2 SSeO 3 ) @ 9.25 kBq g 7 1 soil by incubating at field capacity moisture regime and subjecting to alternate wetting and drying cycles. Following multiple extraction procedure, out of total 75 Se added, 8.8 -26.1% was present in readily available form (0.2 M K 2 SO 4 extractable); 27.6 -49.0% as isotopically exchangeable (0.1M Na 2 SeO 3 extractable) and 5.3 -12.0% as organic Se (0.05 M NH 4 OH extractable). Selenium extractable in K 2 SO 4 was significantly correlated with free iron (r = 7 0.774, p 4 0.05) and CaCO 3 (r = 0.670, p 4 0.10) content of the soils. Negative relationship was observed between Se uptake by maize (Zea mays L.) and ammonium hydroxide extractable (r = 7 0.752, p 4 0.05) as well as residual Se (r = 7 0.726, p 4 0.05) in soils. Highly positive coefficients of correlation between isotopically exchangeable Se and Se content (r = 0.851, p 4 0.01) as well as its uptake by maize (r = 0.841, p 4 0.01) indicated that the isotopically exchangeable form of Se may be considered as an index of bioavailable Se in seleniferous soils of Punjab. None of the fractions defined by following single extraction procedure was correlated with either the soil characteristics or Se uptake by maize plants. Multiple extraction procedure could, thus, better explain the distribution of Se in different fractions and uptake by plants.
Selenium Toxicity in Plants and Environment: Biogeochemistry and Remediation Possibilities
Plants
Selenium (Se) is a widely distributed trace element with dual (beneficial or toxic) effects for humans, animals, and plants. The availability of Se in the soil is reliant on the structure of the parental material and the procedures succeeding to soil formation. Anthropogenic activities affect the content of Se in the environment. Although plants are the core source of Se in animal and human diet, the role of Se in plants is still debatable. A low concentration of Se can be beneficial for plant growth, development, and ecophysiology both under optimum and unfavorable environmental conditions. However, excess Se results in toxic effects, especially in Se sensitive plants, due to changing structure and function of proteins and induce oxidative/nitrosative stress, which disrupts several metabolic processes. Contrary, Se hyperaccumulators absorb and tolerate exceedingly large amounts of Se, could be potentially used to remediate, i.e., remove, transfer, stabilize, and/or detoxify Se-cont...
Abstract The concentration, distribution, and speciation of selenium in different parts of wheat and Indian mustard, grown in a seleniferous area in Punjab, were investigated using synchrotron based (XAS) and classical acid digestion and extraction methods. The analyses revealed a high Se enrichment in all investigated plant parts, with Se levels in the range of 133-931 mg/kg (dry weight, dw). Such high Se enrichment is mainly due to the considerable amounts of easily available Se detected in the soil, which are renewed on a yearly basis to some extent via irrigation. Speciation analysis in soil and plants indicated selenate and organic Se as major Se species taken up by plants, with a minor presence of selenite. The analyses also revealed that the highest Se enrichment occurs in the upper plant parts, in agreement with the high uptake rate and mobility of selenate within plants. In both wheat and mustard, highest Se enrichments were found in leaves (387 mg/kg×dw in wheat and 931 mg/kg×dw in mustard). Organic species (dimethylselenide and methylselenocysteine) were found in different parts of both plants, indicating that an active detoxification response to the high Se uptake is taking place through methylation and/or volatilization. The high proportion of selenate in wheat and mustard leaves (47% and 70%, respectively) is the result of the inability of the plant metabolism to completely transform selenate to non-toxic organic forms, if oversupplied. Methylselenocysteine, a common Se species in 2 accumulating plants, was detected in wheat, suggesting that, in presence of high Se concentration, this plant develops similar response mechanisms to accumulator plants. Keywords Selenium, speciation, wheat, Indian Mustard, synchrotron, XANES
Annual Review of Plant Physiology and Plant Molecular Biology, 2000
Plants vary considerably in their physiological response to selenium (Se). Some plant species growing on seleniferous soils are Se tolerant and accumulate very high concentrations of Se (Se accumulators), but most plants are Se nonaccumulators and are Se-sensitive. This review summarizes knowledge of the physiology and biochemistry of both types of plants, particularly with regard to Se uptake and transport, biochemical pathways of assimilation, volatilization and incorporation into proteins, and mechanisms of toxicity and tolerance. Molecular approaches are providing new insights into the role of sulfate transporters and sulfur assimilation enzymes in selenate uptake and metabolism, as well as the question of Se essentiality in plants. Recent advances in our understanding of the plant's ability to metabolize Se into volatile Se forms (phytovolatilization) are discussed, along with the application of phytoremediation for the cleanup of Se contaminated environments.
2017
Background: Concentrations of Se in seven plant species (white mulberry, apricot, spindle tree, pistachio, wheat, barley, chives), and the associated soil samples were investigated in Shahrood and Damghan, Iran. Materials and Methods: Soil samples were taken from the surface zone (0-5 cm) and plough zone (5-20 cm) in 13 sampling locations. The collected soil and plant samples were taken to the laboratory, then digested usin USEPA's method and analyzed by Inductively Coupled Plasma Optical Emission Spectroscopy technique. Results: Since there was a significant correlation (r=0.688, p<0.01) between Se concentration in the two soil's depths, it was turned out that agricultural practices, through tillage and plough, had probably moved Se to the deeper parts of the soil in area in which agricultural activity was prevalent. The highest accumulation of Se was recorded in the chives with the average value of 0.35mg kg. Except for apricot, the concentrations of Se in top parts of ...