Zinc influence and salt stress on photosynthesis, water relations, and carbonic anhydrase activity in pistachio

A greenhouse study was conducted to evaluate the ameliorative effects of zinc (0, 5, 10 and 20 mg Zn kg−1 soil) under saline (800, 1600, 2400 and 3200 mg NaCl kg−1 soil) conditions on pistachio (Pistacia vera L. cv. Badami) seedlings’ photosynthetic parameters, carbonic anhydrase activity, protein and chlorophyll contents, and water relations. Zn deficiency resulted in a reduction of net photosynthetic rate and stomatal conductance. The quantum yield of photosystem II was reduced at zinc deficiency and salt stress. Zinc improved plant growth under salt-affected soil conditions. Increasing salinity in soil under Zn-deficient conditions, generally decreased carbonic anhydrase activity, protein, chlorophyll a and b contents. However, these adverse effects of salinity alleviated by increasing Zn levels up to 10 mg kg−1 soil. Under increasing salinity, chlorophyll a/b ratio significantly increased. Zinc treatment influenced the relationship between relative water content and stomatal conductance, and between leaf water potential and stomatal conductance. It concluded that Zn may act as a scavenger of ROS for mitigating the injury on biomembranes under salt stress. Adequate Zn also prevents uptake and accumulation of Na in shoot, by increasing membrane integrity of root cells.