Effect of Drought Stress on Some Physiological Traits in Three Varieties of Grapes (Vitis vinifera L.)

Drought stress is one of the most important limiting factors for cultivation and production of grapes in the world and Iran. To study the effect of drought stress on some physiological traits of three cultivars, i.e. ‘Fakhri’, ‘Molaei’ and ‘Ghalati’, a factorial experiment in completely randomized design with three soil water potential treatments. i.e. -0.2 (control), -0.7 and -1.2 MPa was implemented in greenhouse conditions in 2016. In this study, non- grafted grape vines were placed in large 26-liter pots filled with a clay loam textured soil. According to the results of this study, both levels of stress had a significant effect on dry matter to leaf area ratio, cell membrane stability, chlorophyll, proline, and soluble carbohydrates concertation, leaf relative water content, catalase and peroxidase activities. Soluble carbohydrates concentration showed a significant increase of 47 percent compared to control (10.57 mg g-1 DM) in -1.2 MPa stress level. Drought stress decreased the RWC (2 Percent) and increased proline (9 Percent) and malondialdehyde (55 percent) concentration, the peroxidase (15 to 20 percent) and catalase activity (9 Percent). The highest and the lowest chlorophyll concentrations were observed in ‘Ghalati’ (1.63 mg g-1 FM) and ‘Fakhri’ (1.31 mg g-1 FM), respectively. In conclusion, ‘Ghalati’ cultivar had higher potential to withstand drought stress conditions than ‘Molaei’ and ‘Fakhri’ cultivars.