Drought-stress tolerance potential in plum and prune rootstocks and cultivars (Prunus spp.) based on physiological and photosynthetical parameters

Drought stress and water crisis is a great limiting factor for the production of horticultural crops. The present study was carried out during 2021 and 2022 at Horticultural Science Research Institute, Kamalshahr, Karaj, Iran to identify the effect of drought stress in physiological and photosynthetic characteristics of Prunus spp. rootstocks and varieties of 4-year old Prunus spp. The factorial experiment was conducted in a completely randomized block design (CRBD) having 3 factors and 3 replications. Factors included 8 rootstocks, viz. Myrobalan 29C, Penta, Tetra, St. Julien, Mariana 2624, GF 677, GN 15 and Seedling as the first factor; 4 cultivars, viz. Greengage, Simka, NO 16 and Zochelo as the second factor; and drought stress conditions in two levels namely with interruption of irrigation for 14 days and without interruption of irrigation as the third factor. Drought stress decreased relative water content of leaves, stomatal conductance, transpiration, CO2 content in substomatal chamber, and water use efficiency. Zuchelo and Greengage varieties and GN 15 rootstock had the highest and Simka variety and Mariana 2624 and Myrobalan 29C rootstocks had the lowest stomatal exchanges and photosynthesis, respectively. Among the rootstocks; GN 15, GF 677 and Mariana 2624 showed better physiological stability under stress, and the most tolerant variety against drought stress was NO 16. Totally, grafting combination of cv. NO 16 and rootstock GN 15 has been identified as the most tolerant to drought stress.