Physiological and yield responses of rainfed grapevine under different supplemental irrigation regimes in Fars province, Iran

Supplemental irrigation, which provide minimum amount of water under rainfed farming systems, improves the physiological characteristics and yield production of plants especially in arid and semi-arid regions. However, the amount and timing of supplemental irrigation are of utmost importance and challenging with the recent drought occurrences. A two-year field experiment was carried out to study the effect of different supplemental irrigation timings (March, April, May, June, March + April and no irrigation, denoted I-1,I-2,I-3,I-4,I-5 and I-6, respectively) on stomatal conductance (g(s)), photosynthesis rate (An) and leaf water potential of rainfed seedless Table grape, cv. Yaghooti. The I-1,I-2,I-3 and I-4 treatments received 5001 of water, while Is treatments received 10001 of water during the growth season, respectively. The significant maximum berry weight was obtained in the I-3 treatment in both years indicating the efficient use of applied water. Maximum and minimum values of An and gs were 12.10 mu mol m(-2) s(-1) and 0.133 mol m(-2) s(-1) in I-4 (in 114 days after first irrigation initiation), and 6.54 mu mol m(-2) s(-1) for 15 and 0.068 mol m(-2) s(-1) for I-1, respectively. It is concluded that supplemental irrigation during May (I-3) yielded more grape production, although it received less water compared to 15 treatments. (C) 2016 Elsevier B.V. All rights reserved.