Evaluation of oxidative parameters in three grapevine cultivars under drought stress

For evaluation of physiological and biochemical response of some grapevine cultivars to drought stress, an experiment was carried out in 2014 as a factorial arranged in a randomized complete block design with three replications. Three cultivars i. e. “Bidane Sefid”, “Chafte” and “Yaghooti” and four drought stress levels, including -0.3, -0.6, -1 and -1.5 MP soil water potential were employed. In this experiment, two years old grapes were cultured in pots with 28 cm in diameter and 60 cm in height, containing sandy-loam soil in field conditions. Results showed that in “Bidane sefid”, under drought stress (-0.3 to -1.5 MP), RWC, chlorophyll a and b content, and antioxidant enzymes CAT, APX, GPX activity along with DPPH scavenging capacity were declined, but electrolyte leakage, MDA content, LOX enzyme activity (responsible for membrane unsaturated fatty acid peroxidation), along with H2O2 accumulation were increased. Results indicated that ‘Bidane Sefid’ under drought stress had higher oxidative damage, led to lower membrane integrity. In comparison with “Bidane sefid”, “Chafte” and “Yaghooti” under drought stress, due to higher antioxidant enzymes (CAT, APX, GPX) with higher DPPH scavenging capacity, exhibited lower oxidative damage, led to higher membrane integrity. According to our results, it can be concluded that “Chafte” followed by “Yaghooti” had higher potential to tolerate drought stress compared with “Bidane sefid”.