Physiological and Biochemical Responses of Physalis peruviana L. to Salicylic Acid Application under Deficit Water Stress

The use of modifiers in drought stress conditions is an optimal and low cost strategy and understanding the different characteristics of the plant in these conditions leads to achieve appropriate production management methods. The main aim of this study was to investigate the role of salicylic acid concentrations (0, 0.5, 1 and 2 mM) in increasing the tolerance of physalis (Physalis peruviana L.) to deficit water stress in three levels (control, 85 and 75% of the field capacity), which was done in the form of a factorial experiment based on a completely randomized design with 3 replications. The results showed that deficit water stress reduced relative water content (RWC), gas exchanges and stomatal characteristics in the plant. Deficit water stress also affected the activity of antioxidant enzymes, the amount of electrolyte leakage and malondialdehyde caused the amount of these characteristics to increase. Salicylic acid application in this study, reduced the negative effects of stress. According to the obtained results, the length and width of the stomatal guard cell decreased and the stomatal density enhanced under deficit water stress conditions. The amounts of stomatal conductivity, transpiration, carbon dioxide in stomatal chamber (INT Co2), as well as photosynthesis rate showed a decreasing trend at 85% and 75% of field capacity. The highest photosynthesis rate belonged to foliar application of salicylic acid at concentration of 1 and 2 mM. Hence, for the cultivation of physalis in arid and semi-arid regions, irrigation levels of 95% and 85% of the field capacity along with the application of salicylic acid in concentrations of 1 and 2 mM can be suggested, while the irrigation level of 75% FC is not recommended due to the negative effect on the measured parameters.