Physiological and biochemical response of three iranain cultivars grapevine seedling ‘Bidane sefid’, ‘Chafte’ and ‘Yaghooti to drought stress

Grapes with the scientific name (Vitis vinifera L.) belong to the Vitaceae family. Detection, selection and use of grape varieties with drought stress is one of the most important issues in breeding programs and grape production. Therefore, identification, studying and evaluation of physiological and morphological reactions of Iranian grape varieties under drought stress is of great importance in grapevine research. Considering the dispersal of most of Iran's grapes in arid and semi-arid regions, as well as the cultivation of this plant in rainfed form in some provinces of the country such as Kurdistan, Fars, etc., grape plants in part of their annual growth That is, during the summer when excessive evapotranspiration is strongly affected by drought stress and water scarcity, causing problems such as shortening the growth period, reducing flowering and physiological aging and ultimately leading to reduced yield and The plant disappears. To investigate the effect of soil water potential changes on some physiological and biochemical of grape seedlings, an experiment carry out as factorial arranged in a randomized complete block design with three replications with three cultivar including ‘Bidane sefid’, ‘Chafte’ and ‘Yaghooti’ and four drought stress level including -0.3, -0.6, -1 and -1.5 MP soil water potential. After planting seedlings in pots, and reching soil water potential to target level, Electrolyte leakage, malondialdehyde (MDA) content, Lipoxygenase (LOX) enzyme activity, phenylalanine ammonia lyase (PAL) enzyme activity, polyphenol oxidase (PPO) enzyme activities and total phenols accumulation levels were measured in leaves. The results showed that under -1.5 MP soil water potentials ‘Bidane sefid’ had highest levels of electrolyte leakage (31.63%) but ‘Chafte’ and ‘Yaghooti’ had the lowest electrolyte leakage, 24.10 and 25.88 %, respectively. The activity of PAL enzyme under -1 and -1.5 MP soil water potentials in ‘Chafte’ and ‘Yaghooti’ was increased significantly, (under -1.5 MP soil water potentials exhibited highest enzyme activity, 2.45 and 1.97 µmol cinnamic acid. h-1, respectively). However under drought stress levels from -0.3 to -1.5 MP soil water potentials, ‘Bidane sefid’ cultivar had not significantly change in PAL enzyme activity. Under -1.5 MP soil water potentials, ‘Bidane sefid’ exhibited highest PPO enzyme activity (2.78 U.mg-1 protein), but ‘Chafte’ has not significantly change in their PPO enzyme activity. In the ‘Yaghooti’, PPO enzyme activity significantly increased from levels -0.6 to -1 MP soil water potentials. Our results indicated that the ‘Chafte’ under -1.5 Mpa and ‘Yaghooti’ under -1 Mp cultivars had higher tolerance to drought conditions as compared with ‘Bidane sefid’.