Abstract
The aim of this research was to enhance heat stress tolerance potential in local tomato germplasm through exogenous application of salicylic acid (SA) and calcium chloride (CaCl2). Various concentrations of salicylic acid (e.g., control, 2.5 mM, 3.5 mM and 4.5 mM) and calcium chloride (e.g., control, 0.3 mM, 0.4 mM and 0.5 mM) were applied for the duration of forty days. Physiological parameters include (stomatal conductance, photosynthetic rate, transpiration rate and water use efficiency) as well as biochemical attributes (chlorophyll content, enzyme activities of catalase, peroxidase and superoxidase dismutase) of selected tomato genotypes estimated under heat stress conditions. The results revealed that SA and CaCl2 application enhanced vegetative growth of tomato genotypes as compared with control plants. An increased concentration of SA and CaCl2 showed the improved photosynthetic rate, chlorophyll content and induced transpiration rate and stomatal conductance and antioxidant enzyme activity. The study proved that foliar spray of SA and CaCl2 involved in stabilizing the cell as well as cellular integrity under heat stress environment.