Critical Levels of Selenium in Different Crops Grown in an Alkaline Silty Loam Soil Treated with Selenite-Se.

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 μg g−1 soil. Significant decrease in dry matter yield was observed above a level of 5 μg Se g−1 soil in raya and maize; 4 μg Se g−1 soil in wheat and 10 μg 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 μg g−1 in raya, 76.9 μg g−1 in maize, 41.5 μg g−1 in rice and 18.9 μg 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 μg Se g−1. In case of wheat, application of Se more than 3 μg g−1 soil resulted in production of toxic plants. [ABSTRACT FROM AUTHOR]