Some biochemical responses of pistachio to feeding of the common pistachio psylla, Agonoscena pistaciae

The common pistachio psylla, Agonoscena pistaciae is the most important pest of pistachio trees which causes serious damage to pistachio crops. In the present study, we investigated some physiological-biochemical responses of pistachio Akbari cultivar at different feeding periods (2 to 192 h). Hydrogen peroxide contents as stress index had no significant differences between treatments (except for 2 and 96 h treatments). Also a significant decrease was gained in activities of superoxide dismutase (SOD) and catalase (CAT). The lowest activity of SOD, CAT and ascorbate peroxidase (APX) observed at 144 and 192 h. The amount of total protein increased significantly in response to the pest feeding and the lowest concentration observed at the onset of experiment. Total phenolic content increased following psylla feeding while no significant changes observed in total soluble carbohydrates. Amount of the pigments fluctuated in different times of feeding and their elevation after 144 h indicated optimal plant growth under stress conditions. The highest amounts of carotenoids, total phenolic content and total protein after 144 h were associated with the lowest activities of defensive enzymes. Our results showed an appropriate combination of enzymatic and non-enzymatic antioxidants leads to plant conservation and homeostasis regulation under stress conditions.