Metabolic and Enzymatic Responses of Calendula officinalis L. to Foliar Application of Spermidine, Citric Acid and Proline under Drought Stress in a Post Harvest Condition

The first experiment was performed to study the effect of foliar application of spermidine, citric acid and proline (0, 50 and 100 mg L^-1) on some metabolites and enzymatic activities of Calendula officinalis L. under drought stress (No stress: Control, 25, 50, and 75% field capacity). The second experiment was performed to study the effect of foliar application of spermidine, citric acid and proline (0, 50 and 100 mg L^-1) on the post-harvest shelf life of flowers (beginning of the experiment, 5, and 10 days post-harvest). The experiments were factorial in a completely randomized design with 3 replications. All treatments had a significant effect on the measured variables. In the first experiment, FC 25% reduced all traits, FC 75% increased carotenoid, carbohydrate, phenol, flavonoid, protein, Peroxidase (POD) and Superoxide Dismutase (SOD) activities. The highest vitamin C was observed in the control FC. Also, foliar application of 100 mg L^-1 proline, increased carotenoid, carbohydrate and phenol, 50 mg L^-1 proline increased protein content. Also, 100 mg L^-1 of spermidine increased flavonoid and 100 mg L^-1 of citric acid increased vitamin C, SOD and POD activities. In the second experiment, all evaluated traits were reduced ten days after harvest, the highest post-harvest life was for 100 mg L^-1 of citric acid (9.7 days) and the lowest was for the control (5.3 days). The study results showed that application of 100 mg L^-1 spermidine, citric acid and proline with FC 75% improved biochemical properties, nutritional traits, and post-harvest life of Pot marigold.