Evaluation of some physiological and biochemical responses of different wheat cultivars under supplementary irrigation treatments

In the present work, an experimental study on seven different wheat cultivars is carried out to assess the most suitable supplementary irrigation stage and the understanding of physiological and biochemical processes associated with drought tolerance. During the years 2015 and 2016, this experiment is conducted in experimental field of Agriculture and Natural Resources of Kurdistan University as split plot in randomized complete block design with 3 replications under supplementary irrigation conditions at the stemming, boating and flowering stages, respectively. For this purpose, the amount of Hydrogen Peroxide (H2O2), Malondialdehyde (MDA), total protein, the activity of Catalase antioxidant enzymes (CAT), Ascorbate peroxidase (APX), Guaiacol peroxidase (GPX) and superoxide dismutase (SOD) are measured. The analysis of variance showed that there was a significant interaction between cultivars and complementary irrigation in most traits. Based on the obtained results, supplemental irrigation resulted in a decrease in H2O2 levels compared to control. The highest levels of H2O2 and MDA are obtained for Aras, Abughraib and Tamuz cultivars, respectively, whilst the lowest one is obtained for Azar 2. Applying the supplementary irrigation during stemming, boating and flowering stages increased the total amount of protein (except Aras), the activity of CAT and SOD in all cultivars, and also increased the activity of APX in Acsed 65, Rozgari, Semito and Azar 2. Furthermore, it is found that the cultivars Azar 2, Rezgari and Ocsede 65, with supplementary irrigation at flowering stage, were able to control the existing conditions by defining their defense mechanisms.