REGULATING EFFECTS OF EXOGENOUS SALICYLIC ACID APPLICATION ON WHEAT GROWTH UNDER SALINE AND HEAT STRESS CONDITIONS.

Salicylic acid (SA) has emerged as an excellent phyto-hormone to improve stress tolerance in plants. However, no information is available about the role of SA under combined SS and HS. Therefore, this study was performed to underpin the potential role of SA to mitigate SS and HS in wheat crop. The study was comprised of different treatments: control, SS (8 dS m^-1), HS (imposed at flag leaf stage) and combination of SS (8 dS m^-1) and HS and different levels of SA: control, 50 mM, 100 mM and 150 mM. Salinity and HS substantially decreased the growth, and yield traits of wheat that was linked with increased electrolyte leakage (EL), malondialdehyde (MDA) and hdrogen peroxid (H₂O₂) production, sodium (Na⁺) and chloride (Cl^-) accumulation and decrease in relative water contents (RWC), photosynthetic pigments, total soluble proteins (TSP) and free amino acids (FAA) accumulation and nutrient uptake. Nonetheless, foliar applied SA particularly 150 mM appreciably improved the growth and yield of wheat crop by increasing RWC, antioxidant activity soluble sugars, proline, TSP, FAA accumulation, nutrient uptake and decreasing EL, electrolyte leakage, MDA and H₂O₂ and restricting the entry of toxic ions. Therefore, these findings suggested that SA could improve the growth and yield of wheat under SS and HS stresses by improving physiological activity, photosynthetic pigments, antioxidant activity and accumulation of osmolytes. [ABSTRACT FROM AUTHOR]