Abstract
Background: Guava (Psidium guajava L.) is a highly perishable climacteric fruit characterized by a rapid ripening process and a short post-harvest life, which leads to significant economic losses. Melatonin has emerged as a potent antioxidant and signaling molecule capable of delaying senescence and preserving fruit quality. Methods: A field experiment was conducted using a Randomized Block Design (RBD) with four replications. Guava trees were subjected to five preharvest treatments: T1 (Control), T2 (50 µM), T3 (100 µM), T4 (150 µM) and T5 (200 µM) melatonin. The treatments were applied as foliar sprays two weeks prior to the anticipated harvest date. Result: Among the concentrations tested, fruits treated with 100 µM melatonin maintained significantly higher firmness, titratable acidity, ascorbic acid (Vitamin C) and total phenolic content compared to the control group. Furthermore, this treatment effectively minimized physiological loss in weight (PLW) and extended the shelf life of the fruits up to 9 (8.73) days under ambient conditions.