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. (C) 2009 Elsevier B.V. All rights reserved.