STUDIES ON SELENIUM TOXICITY TOLERANCE AND OXIDATIVE RESPONSES IN WHEAT CULTIVARS
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Date
2013
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Punjab Agricultural University
Abstract
Studies on effect of selenium on its accumulation, biochemical composition and
oxidative responses in three wheat cultivars viz PDW 291, PBW 550 and TL 2908 during
different stages of crop development have been carried out. Plants were grown on soil treated
with solutions of sodium selenate @ 2 and 4 mg kg-1 soil and leaves were subjected to
biochemical analysis at 55 and 85 days after sowing and grains at maturity. Selenate treated
plants accumulated higher selenium in roots, stems, leaves and grains as compared to control
plants. Total dry matter yield per pot of selenate treated plants decreased significantly as
compared to their respective controls. Selenate treated plants showed growth retardation,
snow white chlorosis with pink colouration on the lower side of leaves, decreased shoot
length, reduced leaf area and produced less number of grains as compared to control plants.
Maximum reduction in these parameters was observed in selenium treated TL 2908 plants and
most of the plants died before maturity with almost no grain formation with higher dose (4
mg Se kg-1 soil). Significant increase in hydrogen peroxide, ascorbic acid and lipid
peroxidation and decrease in chlorophyll content were observed in selenium treated leaves in
these cultivars. However, activities of antioxidant enzymes such as catalase, peroxidase and
superoxide dismutase showed varied response to selenium application. Selenium
accumulation resulted in decreased total reducing sugars, starch and protein content in grains
whereas total free amino acids increased significantly in all the three cultivars. Selenium
accumulation in wheat showed metabolic disturbances and its accumulation in wheat grains
was beyond toxic levels thus making it unfit for consumption
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Keywords
planting, wheats