Foliar applications of alpha-tocopherol improves the composition of fresh pods of Vigna radiata subjected to water deficiency

Abstract

Alpha-tocopherol (α-Toc), so-called vitamin E, is a low molecular weight lipophilic antioxidant that generally protects plants from stress-induced cellular oxidation. It is well known that exogenously applied α-Toc is effective in improving plant growth and developmental processes under adverse environmental conditions. The current study was performed to determine the best concentration of α-Toc [0 (no spray), 100, 200, and 300 mg L-1] that could improve the biological yield and chemical constituents of fresh green pods of mung bean (Vigna radiata) and hence their quality under varying water regimes. Foliar spray of α-Toc significantly improved total soluble proteins, chlorophyll a and b, total soluble sugars, proline, phenolics, total free amino acids, nonreducing sugars, and activities of SOD, POD, and CAT under water stress conditions. However, no prominent change was observed in reducing sugars and biological yield due to externally applied α-Toc in either mung bean cultivar subjected to either water regime. Both mung bean cultivars (Cyclone 7008 and Cyclone 8009) showed similar behavior in chlorophyll a and b, while cv. Cyclone 7008 was superior with respect to the concentrations of total soluble sugars and total free amino acids, whereas Cyclone 8009 was better in activities of CAT, SOD, and POD. Overall, externally applied 200 and 300 mg L-1 α-Toc considerably enhanced the activities of antioxidant enzymes (SOD, POD and CAT), chlorophyll a and b, proline, and total phenolic contents in both mung bean cultivars.