Physiological responses and anti-oxidative activities in flag leaves and spicules of wheat genotypes (Triticum aestivum L.) under drought stress

This study was carried out for evaluation of the effects of drought stress after anthesis on agronomic characteristics and some physiological responses of flag leaves and spicules of different wheat genotypes using a factorial experiment in a randomized complete block design with two factors (irrigation and wheat genotypes) and three replicates. Two levels of irrigation involving control (full irrigated under water farming conditions) and drought stress (irrigation cut after anthesis until the end of growth period) as the first factor and different wheat genotypes (TEVEE'S'//CROW/VEE'S and Shark: drought sensitive, Manning/Sdv1/Dogu8 and Sabalan: semi tolerant, Sardari HR-86 and Dogu88/Ghafghaz 7: tolerant to drought stress) as the second factor were considered and agronomic and physiological characters were measured. Drought stress decreased grain yield through decreasing 1000 grains weight. Manning/Sdv1/Dogu8 semi tolerant genotype showed the highest and Shark genotype showed the lowest grain yields. Results showed that soluble protein content increased in flag leaves and spicules under stress compared to control. Sardari HR-86 and Shark genotypes showed the highest and lowest soluble protein content in flag leaves, respectively. The highest  and lowest soluble protein contents in spicules were observed in Manning/Sdv1/Dogu8 and Shark genotypes, respectively. The study also showed that peroxidase, ascorbate peroxidase, and superoxide dismutase enzymes activities increased under drought. The highest enzyme activity was observed in flag leaves of Sardari HR-86 tolerant genotype and in spicules of Manning/Sdv1/Dogu8 semi tolerant genotype in the last step of sampling. Also, sensitive genotypes showed the lowest enzyme activities. Based on the obtained results it seems that in Manning/Sdv1/Dogu8 semi tolerant genotype, activation defense system of peroxidase and superoxide dismutase enzymes had a key role in improving tolerance to drought stress.