Effect of long-term salinity on growth, chemical composition and mineral elements of pistachio (Pistacia vera cv. Badami-Zarand) rootstock seedlings

In recent years, one of the most important problems of pistachio growing is increasing the salinity of soil and water which has decreased the quality and quantity of this crop. In this study, the effect of different levels of salinity on growth of pistachio rootstock cv. Badami Zarand has been evaluated. Pistachio seeds were planted in pots containing loamy sand soil and the salinity treatments were performed four weeks after germination. Seedlings were treated with 25, 50, 100 and 150 Mm of NaCl, CaCl₂ and MgCl₂ with SAR: 13 that were conducted in 8 steps gently. After 50 days, at the end of salinity duration, seedlings were harvested and morphological traits (length and diameter of shoots and roots as well as fresh and dry weight of shoots and roots) were recorded. Biochemical factors (proline, reduced sugar, starch) and mineral elements (Na⁺, K⁺, Cl^- and Na⁺:K⁺) were also measured.

Results showed that growth characteristics (fresh and dry weight of shoots and roots and shoot height) were decreased under salinity stress especially in 150 Mm treatment but the length of root was not significantly affected. Although the concentration of reduced sugars and proline in the leaves were decreased in150 mM salinity, there was no significant difference among other treatments. Results also showed that the tissue concentrations of Na⁺, Cl^- and Na⁺: K⁺ ratio were increased with increasing the salinity level, while the increasing of Na concentration and Na⁺:K⁺ ratio was significant only in 150 Mm salinity. Lower Na⁺:K⁺ ratio in shoots suggests the possible better K⁺- Na⁺ discrimination by carrier in cell root or K⁺ versus Na discrimination at the sites of xylem loading.