Physiological, Biochemical, and Developmental Responses of some Pistachio Genotypes under Drought Stress

Pistachio is one of the economic nut fruits in Iran. Water limitation is the most restrictive factor for its production. To overcome the water scarcity crisis, introducing drought-tolerant rootstocks is among the crucial breeding strategies. To investigate the drought tolerance of five Qazvin native pistachio genotypes, an experiment was carried out as a factorial experiment in a completely randomized design with four replications in the greenhouse conditions. The factors were pistachio genotypes (Madari, KalKhandan, Kalehbozi, Sefid, and Ghermez) and irrigation regime (normal conditions and drought stress). The highest relative water content under drought irrigation conditions belonged to the Sefid (59.99%), and Ghermez (59.09%) genotypes. The lowest value (54.68%) belonged to the Madari genotype. The highest electrolyte leakage under drought irrigation conditions belonged to the Madari genotype (55.75%). The lowest electrolyte leakage (42.44%) belonged to the Sefid genotype. Under drought stress, the highest amount of chlorophyll a (2.12 mg g-1 fresh weight), total chlorophyll (3.051 mg g-1 fresh weight), and carotenoid (2.38 mg g-1 fresh weight) was observed in Ghermez genotype. In contrast, the highest amount of chlorophyll b (1.34 mg g-1 fresh weight) was observed in the Sefid genotype. The lowest amounts of chlorophyll and carotenoid in the drought stress belonged to the Madari genotype. According to the results, the Ghermez and Sefid genotypes with lower electrolyte leakage and higher relative water content, chlorophyll, carotenoid, and biomass under water stress, were the more drought-tolerant genotypes. Madari and KalKhandan genotypes with higher electrolyte leakage and lower relative leaf water content, chlorophyll, and biomass were the most drought-sensitive genotypes.