Drought-induced changes in plant-yield interlinked biochemistry of cauliflower (Brassica oleracea L. var. botrytis) by exogenously applied alpha-tocopherol

To assess the potential of exogenously-applied vitamin E commonly known as alpha-tocopherol (α-TOC) in drought stress tolerance, an experiment was performed on cauliflower (Brassica oleracea L. var. botrytis) plants. Two cultivars (TCF-605 and White Figer) of cauliflower were subjected to control and drought stress conditions. After thirty days of drought stress treatment, cauliflower plants were treated with α-TOC (150 and 300 mg/L) as a foliage spray. Drought stress markedly inhibited the plant biomass, leaf characteristics such as relative water contents (RWC), chlorophyll pigments (a and b), proline, ascorbic acid (AsA), GB, however it elevated RMP, total phenolics, activities of antioxidant enzymes e.g., CAT, SOD and POD. Drought stress also adversely affected curd characteristics including its fresh weight, GB, proline, total phenolics and enzymes activities (SOD and CAT). Exogenously applied α-TOC considerably suppressed RMP, while it improved plant growth, yield, RWC, total phenolics, ascorbic acid and POD, SOD, and CAT enzyme activities in the leaves of the cauliflower. Exogenous application of α-TOC also raised curd total phenolics, AsA and the activities of all observed enzymes under water deficiency. The cv. TCF-605 was better in shoot weight, shoot length, RWC, proline as well as GB contents, while cv. White Figer was higher in leaf RMP, proline and AsA levels under drought stress conditions. Overall, the results exhibited that cauliflower cv. TCF-605 was relatively tolerant to water stress in relation to growth and yield outcomes, which was interlinked with α-TOC-induced improved leaf and curd osmoprotection and antioxidative defense system. So, exogenous application of α-TOC can be suggested for improving growth and yield potential of crops subjected to drought stress.