Effect of exogenous application of ascorbic acid on physiological and biochemical characteristics of wheat under water stress

Wheat (Triticum aestivum L.) is widely cultivated in the Mediterranean zone where plantsgenerally suffer from water stress during heading and reproductive stages. This research wascarried out at the experimental farm of the faculty of agriculture, Kafrelsheikh University usingtwo water treatments (water stress and well-watered), four N levels (0, 80, 160 and 240 kg ha-1)and two ascorbic acid levels (0 and 200 mg l-1). Water stress substantially reduced yield andrelated-traits compared with well-watered crop; however, AA application improved yieldproductivity and chlorophyll content was associated with the maintenance of leaf water statusunder water stress. Catalase (CAT) and peroxidase (POX) activity showed significant increasesin plants treated with ascorbic acid (AA) under water stress. Among different nitrogen levels,the highest N level (240 kg N ha-1) performed better during 2012/2013 and 2013/2014 seasons.Under water stress condition the higher N level (240 kg ha-1), despite determining an increase ingrain N content, did not imply an increase in NUE, due to a decrease in grain yield whichpositively related to N uptake. Exogenous application of ascorbic acid (AA) has been foundvery effective in mitigating the adverse effects of water stress, which might be attributed byactivities of antioxidant enzymes (CAT and POX). In addition, inducing a stimulatory effect onall the yield-related traits. Maximum productivity and related traits were recorded under wellwatered condition treated by 240 kg N ha-1. Nonetheless, exogenously applied ascorbic acid hasbetter able to produce appropriate productivity under water stress.