Critical Levels of Selenium in Different Crops Grown in an Alkaline Silty Loam Soil Treated with Selenite-Se (original) (raw)
Related papers
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.
Tolerance of wheat (Triticum aestivum L.) to high soil and solution selenium levels
Plant and Soil, 2005
The fertilisation of wheat crops with Se is a cost-effective method of enhancing the concentration of organic Se in grain, in order to increase the Se intake of animals and humans. It is important to avoid phytotoxicity due to over-application of Se. Studies of phytotoxicity of Se in wheat grown in Australia, where rainfall and grain yield are usually relatively low, have not been reported previously, and overseas studies have had varied results. This study used trials conducted in the field, glasshouse and laboratory to assess Se phytotoxicity in wheat. In field trials that used rates of up to 120 g ha −1 Se as selenate, and in pilot trials that used up to 500 g ha −1 Se soil-applied or up to 330 g ha −1 Se foliar-applied, with soils of low S concentrations (2-5 mg kg −1 ), no Se toxicity symptoms were observed. In pot trials of four weeks' duration, the critical tissue level for Se toxicity was around 325 mg kg −1 DW, a level attained by addition to the growth medium of 2.6 mg kg −1 Se as selenate. Solution concentrations above 10 mg L −1 Se inhibited early root growth of wheat in laboratory studies, with greater inhibition by selenite than selenate. For selenite, Se concentrations around 70 mg L −1 were required to inhibit germination, while for selenate germination % was unaffected by a solution concentration of 150 mg L −1 Se. Leaf S concentration and content of wheat increased three-fold with the addition of 1 mg kg −1 Se as selenate to the growth medium. This effect is probably due to the induction of the S deficiency response of the main sulphate transporter. This study found wheat to be more Se-tolerant than did earlier studies of tobacco, soybeans and rice. We conclude that Se phytotoxicity in wheat will not be observed at the range of Se application rates that would be used to increase grain Se for human consumption (4-200 g ha −1 Se as selenate, which would result in soil and tissue levels well below those seen in the above studies), even when -as is common in Australia -soil S concentration and grain yield are low.
Chemosphere, 2007
Greenhouse experiments were conducted to study the bioavailability of selenium (Se) to sorghum (Sorghum bicolor L.), maize (Zea mays L.) and berseem (Trifolium alexandrinum L.) fodders in a sandy loam soil amended with different levels of Se-rich wheat (Triticum aestivum L.) and raya (Brassica juncea L. Czern) straw containing 53.3 and 136.7 lg Se g À1 , respectively. Each of the fodder crops was grown after incorporation of Se-rich materials either individually or in a sequence -sorghum-maize-berseem by incorporating Se-rich straws only to the first crop. Application of Se-rich straws to each crop, even at the greatest rate of 1%, did not have any detrimental effect on dry matter yield of different crops. With increase in the level of wheat straw from 0% to 1%, Se content in sorghum and maize plants increased to greatest level of 1.3 and 1.5 lg g À1 , respectively, at 0.3% of applied straw and thereafter it decreased consistently. In case of raya straw, the greatest Se content in sorghum (2.3 lg g À1 ) and maize (3.0 lg g À1 ) was recorded at 0.3% and 0.4% of the applied straw, respectively. Unlike sorghum and maize fodders, Se content in all the four cuts of berseem continued to increase with increase in the level of applied straws and for different cuts of berseem it varied from 1.6 to 2.3 and 3.4 to 4.3 lg g À1 in case of wheat and raya straw, respectively. Similar variations in Se content of different fodder crops were recorded when these were grown in the sequence -sorghummaize-berseem; but Se content was 2-4 times lower than when each crop was grown with fresh application of Se-rich straw. None of the fodders absorbed Se in levels toxic for animal consumption (>5 lg g À1 ) even at the greatest level of applied straw. Of the total Se added through Se-rich straws, utilization of Se was not more than 2% in case of sorghum and maize crops and up to 5% in case of berseem.
Plant and Soil, 2013
Aims A comparison was performed between plant species to determine if extractable, rather than total soil Se, is more effective at predicting plant Se accumulation over a full growing season. Methods Durum wheat (Triticum turgidum L.) and spring canola (Brassica napus L.) were sown in potted soil amended with 0, 0.1, 1.0, or 5.0 mg kg −1 Se as SeO 4 2− or SeO 3 2−. In addition, SeO 4 2−-amended soils were amended with 0 or 50 mg kg −1 S as SO 4 2−. Soils were analyzed for extractable and total concentration of Se ([Se]). Twice during the growing season plants were harvested and tissue [Se] was determined. Results Plants exposed to SeO 3 2− accumulated the least Se. Fitted predictive models for whole plant accumulation based on extractable soil [Se] were similar to models based on total [Se] in soil (R 2 =0.73 or 0.74, respectively) and selenium speciation and soil [S] were important soil parameters to consider. As well, soil S amendments limited Se toxicity. Conclusions Soil quality guidelines (SQGs) based on extractable Se should be considered for risk assessment, particularly when Se speciation is unknown. Predictive models to estimate plant Se uptake should include soil S, a modifier of Se accumulation.
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.
Selenium and agricultural crops
African Journal of Agricultural Research, 2017
Higher plants have different capacities to accumulate and tolerate selenium, referred to as accumulative and non-accumulative plants. Selenium-accumulators plants may contain hundreds of times more selenium than non-accumulators even when grown in the same soil, or can also grow in soils with low and medium selenium reserves; while selenium non-accumulator plants present low accumulation and tolerance to high selenium levels in the culture medium. Several studies have demonstrated the protective role of selenium in relation to oxidative stress in plants. Depending on the dose used, Se can activate certain enzymes such as superoxide dismutase, glutathione reductase and glutathione peroxidase. These enzymes are activated in the presence of Se, reducing the rate of lipid peroxidation and formation of hydrogen peroxide in plant tissue cells, which results in reduced senescence. Symptoms of selenium toxicity include reduced growth, chlorosis of leaves and pink coloration of the roots, yellowing of leaves and black spots. Studies provide evidence on a beneficial role of Se in plants and for environmental phytoremediation. However more research is needed to consolidate the beneficial effects of Se in plants.
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.