Using Morphological and Physiological Traits to Evaluate Drought Tolerance of Pear Populations (Pyrus spp.)

The use of drought-tolerant rootstocks is one of the available solutions for the cultivation of pear in semi-arid areas. In order to achieve drought-tolerant rootstocks, seeds of Pyrus syriaca, and Pyrus salicifolia species as well as Pyrus communis cv. Spadona, Khoj no. 1 and Khoj no. 2 were cultivated in the field conditions. This research was carried out as a factorial experiment with two factors of pear species (in five levels) and water stress (in two levels of control and drought stress) based on a randomized complete block design. In drought treatment, the irrigation time was considered based on 80% of allowed water depletion. In control blocks, normal irrigation was performed. The experiment began in July and continued to late September. In stress conditions, P. communis cv. Spadona and Khoj no. 1 had the highest seedling height and stem diameter and P. salicifolia and P. communis cv. Khoj no. 2 had the lowest of the rate of these traits. The lowest increase in electrolyte leakage (EL) and the highest proline content were in P. communis cv. Khoj no. 2 and P. salicifolia and the highest EL and the lowest proline were observed in P. communis cv. Spadonain under drought stress conditions. The most and the least relative water content (RWC) were belonged to P. communis cv. Khoj no. 2 and Spadona, respectively, in stress conditions. According to the studied traits, P. salicifolia and P. communis cv. Khoj no. 2 populations were more tolerant to drought stress.