Response of eggplant (Solanum melongena L.) to exogenously applied alpha-tocopherol under drought stress conditions

Abstract

In current study, two eggplant cultivars Sultan F1 (drought sensitive) and Janak F1 (drought tolerant) were used for the experimentation. The plants were grown in pots filled with equally weighed soil. In one experiment, seeds of both eggplant cultivars were primed for 16 hours with α-tocopherol (0, Water, 0.25, 0.5 and 1 mM) whereas in another experiment seeds were sown without priming treatments. Drought stress (100 % field capacity and 50% field capacity) was applied after 20 days of sowing. In second experiment, foliar application of α-tocopherol (0, Water, 0.25, 0.5 and 1 mM) was applied after 20 days of drought application. Drought stress adversely affected the both eggplant cultivars however, α-tocopherol application through seed priming and foliar application significantly increased growth attributes, photosynthetic pigment levels in both eggplant cultivars. Exogenous 0.5 and 1 mM of α-tocopherol levels were much more effective in increasing shoot, root fresh and dry weight, root and shoot lengths, chlorophyll, carotenoids, lycopene, No. of fruits/plant and fruit yield/plant in both eggplant cultivars. Irrespective of mode of application increased oxidants such as contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in eggplant. The exogenous α-tocopherol increased antioxidants such as content of ascorbic acid (AsA), total free proline and activities of enzymatic (peroxidase, catalase and ascorbate peroxidase) antioxidants in both eggplant cultivars. The shoot and root mineral ion contents (Na+, K+ and Ca2+) increased with α-tocopherol exogenous application in eggplant cultivars. Shoot potassium and calcium content significantly increased by 0.5 and 1 mM α-tocopherol applied as seed priming and as foliar spray at vegetative stage. In conclusion, 0.5 and 1 mM levels were more effective in increasing the level of yield and growth along with decreasing the alleviate effect of drought stress in eggplant.