Changes in some physiological and osmotic parameters of several pistachio genotypes under drought stress

- The genotype Badami-Rize-Zarand showed a better performance under the highest level of drought stress in comparison with the other genotypes with respect to keeping growth and relative water content (RWC).
- Under drought stress, accumulation of measured osmolytes were more in leaves than root.
- Vegetative growth, RWC, total chlorophyll (TChl), carotenoids and TSP decreased by increasing drought levels in all genotypes.
- MDA and H2O2, some osmoregulators (proline, glycine betaine, total soluble carbohydrate and sucrose) and TPC raised under drought stress in all genotypes.

Drought is one of the main adverse environmental factors, obviously has an impact on plant growth and development. Many adaptive strategies have been developed in plants for dealing with water stress, among which osmoregulation is one of the most important factors of drought-tolerance in plants. The objective of this study was to evaluate the effect of drought stress on the physiological and osmotic parameters of several pistachio genotypes. A completely randomized design was applied with a factorial arrangement of two factors: drought (0, −0.5, −1 and −2 MPa) and genotypes (Abareqi, Badami-Rize-Zarand, Qazvini, and Sarakhs) at four replications. The results indicated that drought stress reduced shoot and root dry weight (RDW), leaf area, leaf relative water content (RWC), total chlorophyll (TChl), carotenoids, total soluble proteins (TSP) and increased proline, glycine betaine, total soluble carbohydrate (TSC), sucrose, phenol, hydrogen peroxide (H2O2) and malondialdehyde (MDA) content in roots and leaves of four genotypes. The genotypes have differently responded to water stress. The highest and lowest of above parameters in the roots and leaves of pistachio seedlings under drought condition were found in Badami-Rize-Zarand and Abareqi genotypes, respectively. According to the results, Badami-Rize-Zarand was presented more resistance to drought stress as accumulated more osmolytes and produced better water relations and dry weights under drought stress.