COMPARISON AND SYNERGISTIC IMPACT OF ALOE VERA LEAF EXTRACT AND SALICYLIC ACID ON THE PHYSIOLOGICAL AND BIOCHEMICAL ADAPTATION OF CACAO CULTIVARS TO SALINE STRESS

Salinity is one of the significant abiotic stress factors that accentuate the growth of Theobroma cacao L., severely limiting its growth, physiological performance, and yield potential. The current paper examined the role of Aloe vera leaf extract (AVE) and salicylic acid (SA) used individually and in combinations in the physiological and biochemical responses of two cacao plants (CCN-51 and ICS-95), under 100 mM NaCl-induced salinity. Salinity had a huge impact on reducing the growth of the plants, the ratio of water to the material (RWC), chlorophyll pigmentation, and the concentration of potassium (K+), and elevated electrolyte leakage (EL), sodium (Na+) accumulation, and the indicators of oxidative stress. Foliar treatment of SA and AVE as a single or combined agent had significant alleviating effects against salt stress, which included the maintenance of membrane stability, osmotic adjustment, antioxidant defense system strengthening, and ionic homeostasis. The SA+AVE treatment had the strongest effect on the increase in chlorophyll content, antioxidant enzyme activities (superoxide dismutase, peroxidase, and catalase), and K+/Na+ ratio, and a significant decrease in the electrolyte leakage and Na+. CCN-51 was found to have a relatively high salt tolerance among the two cultivars, and this is related to an effective antioxidant mechanism and high ability to lose ions. On the whole, the combination of Aloe vera extract and salicylic acid is a potentially dependable and environmentally friendly approach that allows to increase salt tolerance and cacao yield in a salty environment.