INTERACTIVE EFFECTS OF ABSCISIC ACID (ABA) AND DROUGHT STRESS ON THE PHYSIOLOGICAL RESPONSES OF WINTER WHEAT (TRITICUM AESTIVUM L.)

Water deficit is confirmed to be the most destructive factor in abiotic stress, which can inhibit crop growth. Here we examined the effect of exogenous applied 10 mu M abscisic acid (ABA) on the physiological and biochemical responses to water deficit in winter wheat (Triticum aestivum L) over a 12-day period at seedling stage. ABA application by root irrigation was transported to the aboveground part to increase the leaf ABA accumulation, which led to the decrease of leaf stomatal conductance (Gs) to reduce water loss. Drenching the soil with ABA trigged an early closure of stomata in the leaves of winter wheat, resulting in broadened the soil water content (SWC) threshold range of non-hydraulic root-sourced signal (nHRS). Exogenous application of ABA also decreased the leaf hydrogen peroxide (H2O2) content and increased SOD, CAT and POD activities, leading to reduce the damage of free radicals accumulation on the structure of cell membrane system in wheat plants. Collectively, these results suggested that exogenously applied ABA under drought stress confer growth promoting and stress relieving effects on wheat plants.