Impact of drought and high temperature stress on oxidants and antioxidants in greengram (Vigna radiata (L.) Wilczek)

Drought and high temperature often occur simultaneously due to climate change which cause devastating effects in plants due to oxidative damage. This study aimed to quantify the oxidant production and antioxidant activity during combined drought (D) and high temperature (HT) stress. A set of greengram genotypes were grown in rainout shelter by pot culture and the plants were exposed to drought and high temperature stress by sowing the seeds in such a way that the vegetative stage coincide with high temperature stress (> 36±2°C) and the control plants (< 36±2°C). Irrigation was withheld for five days by maintaining the field capacity (50%) in stressed plants and (100%) in non stressed plants. The oxidants such as hydrogen peroxide, superoxide radical and melondialdehyde content were increased under stress condition and leads to increase in membrane damage. This effect can be minimized by increase in enzymatic and non-enzymatic antioxidant. Therefore the tolerance capacity of the genotypes is based on the tolerance against the oxidative stress by antioxidant activity.