Foliar Application of K-Silicate and L-Cysteine Enhances Production, Quality, and Antioxidant Activities of Cape Gooseberry Fruits Under Drought Conditions

Water deficit is a notable environmental stress, which leads to negative impacts on crop growth, resulting in yield decline. In the current experiment, the exogenous application of potassium silicate (KSi) and L-cysteine (Cys) was investigated on the productivity, qualitative, and biochemicals of Cape gooseberry fruits subjected to drought stress condition in a 2-year field experiment (2022 and 2023). Our findings indicated that deficit irrigation reduced yield, the membrane stability index, titratable acidity, and the ascorbic acid content of fruits in comparison to the untreated plants in both years. Nonetheless, MDA, H2O2, and antioxidant enzyme activities were meaningfully enhanced as a consequence of water deficit conditions. The application of KSi and Cys alleviated water deficit stress by reducing MDA accumulation and provided significantly greater content of total soluble solids, soluble carbohydrate, proline, total soluble protein, total phenols, and flavonoids. KSi and Cys have a positive influence on H2O2 accumulation by boosting the actions of antioxidant enzymes. Furthermore, higher values of Cys induced the production of proline, APX, PPO, and PAL activities, which contributed to decreasing the damaging effects of plant drought stress and led to an enhanced yield rate. Overall, the foliar application of KSi and Cys by improving antioxidant components, antioxidant enzyme activity, and proline accumulation had a positive impact on the productivity and quality of Cape gooseberries cultivated under standard and shortage irrigation levels.