Effect of Salicylic Acid and Irrigation Water Quality on Pistachio in Pumice Substrate

Pistachio is one of the most important commercial trees grown in Iran arid and semi-arid regions. Salt stress has been reported to cause an inhibition of growth and development, reduction in many plant characteristics. Adverse effects of salinity on growth, and characteristics of pistachio have demonstrated. Salicylic acid (SA) is known to have an affect on normal conditions and stresses in plants. This study evaluated the vegetative characteristics (fresh and dry weight of shoot and root) and physiological characteristics (chlorophyll) as responses to salinity and salicylic acid in pistachio under a pumice substrate. A factorial experiment was conducted on the basis of a completely randomized design with three replications at the research greenhouse of Islamic Azad University of Damghan. The study was designed to evaluate two factors , included 9 treatments at  three  replication .The first factor was three levels  of irrigation water salinity including :  Ecw0 = 2.7 dS.m-1 ,  Ecw1 = 4   dS.m-1  , Ecw2 = 8   dS.m-1 .The second factor was salicylic acid  with three concentrations as following: 0 mg.l-1(control) ,  80 mg.l-1  and  160 mg.l-1. The studied   parameters were fresh and dry weight of the shoots & roots and chlorophyll a. Analysis of variance indicated significant differences due to salinity and salicylic acid on fresh and dry weight of shoot and root of pistachio at the all levels in comparison with the control. The interaction between the salicylic acid concentrations and type of irrigation water gave significant differences in all of the study parameters (except for chlorophyll a). The most significant results were obtained with salicylic acid treatment at 160 mg.l-1. Results indicated that salinity treatments decreases studied parameters including: Shoot (FW), Shoot (DW), Root (FW), Root (DW) and Chlorophyll a. Results showed that lower salinity brings improved plant growth. Results showed that salicylic acid improved the chlorophyll a content of pistachio.