Selenate and Selenite Induced Differential Morphophysiological Modifications to Mitigate Arsenic Toxicity and Uptake by Wheat

This study (pot experiment) investigated and compared the effectiveness of Se(VI) and Se(IV) application at a rate of 1.25 mg Se kg−1 soil on growth, physiology, yield and As uptake by spring wheat on an uncontaminated and As-contaminated (1.5 mg kg−1) soil. Selenate improved wheat grain yield, relative water contents, membrane stability index, total chlorophylls, and antioxidant activities up to 43%, 18.6%, 9.5%, 16.4% and 15–46%, respectively, compared to control under As-contaminated soil. As compared to Se(IV), in accordance with above results, Se(VI) application resulted in 5-fold higher grain Se concentration and 4.4-fold higher grain Se uptake, which are partially explained by 1.3-fold higher root to grain Se translocation factor in Se(VI)-fed plants under As-contaminated soil. Concomitantly, Se(VI) offered a stronger competitive effect on As uptake thereby reducing its concentration in grains by 11% and in shoots by 44%. Translocation factor of As from root to shoots and to grains was 33% and 14.2%, respectively lesser in Se(VI)-fed plants. Thus, it is concluded that Se(VI) application, through its beneficial effects on root morphological traits, improvement in antioxidant activity and physiological behavior, is highly effective in reducing As toxicity on yield and As accumulation in wheat grains.