Effects of Drought Stress on Enzymatic and Non- Enzymatic Antioxidants in Flag Leaf and Spikes of Tolerant and Sensitive Wheat Genotypes

  Drought stress is one of the main limiting factors in plant production in semiarid regions; this is due to its oxidative stress. For evaluation of drought stress after pollination on some agronomic physiological factors in flag leaf and spikes of different wheat genotypes this study was designed as Randomized Complete Block Design with three replicates in Maragheh dryland research center in 2016. The first factor contains two levels of irrigation, control and drought stress (irrigation cut after pollination until the end of growth period) and the second factor contains different wheat genotypes (PTZ and TRK: tolerant, Manning and Sabalan: semi tolerant, Saratoves and RINA-11: sensitive). Drought stress decreased grain yield. Manning semi tolerant and Saratoves sensitive genotypes showed the highest and lowest grain yield. The activities of enzymatic (ascorbate peroxidase and glutathione reductase) and non- enzymatic (glutathione and ascorbate) antioxidants increased under drought stress. The highest and lowest ascorbate peroxidase enzyme activity was observed in flag leaf of TRK and Saratoves genotypes and in spikes of Manning and Saratoves genotypes. Also flag leaf and spikes of Manning and Saratoves genotypes showed the highest and lowest glutathione reductase enzyme activity. The highest glutathione and ascorbate content in flag leaf and spikes was related to TRK and Manning genotypes; the lowest content was observed in Saratoves. It seems that in spikes of Manning genotype, activation of enzymatic (ascorbate peroxidase and glutathione reductase) and non-enzymatic (glutathione and ascorbate) antioxidants had a key role in increase of tolerance to drought stress.