Foliar or irrigation application of salicylic acid and methyl jasmonate regulate postharvest ripening and chilling tolerance of green pepper fruit by modulating both antioxidant and lipid metabolism

Abstract

Green pepper quality deteriorates during cold storage due to membrane lipid damage and oxidative stress, leading to chilling injury (CI). The main aim of this study is to investigate the effects of preharvest applications of 0.5 mM salicylic acid (SA) and 0.1 mM methyl jasmonate (MeJA) on ’Herminio’ green peppers, applied via foliar spraying and irrigation, to enhance chilling tolerance. Therefore, the physiochemical traits, CI incidence, antioxidant metabolism, and fatty acid (FA) composition after 28 days at 2◦C followed by 2 days at 20◦C (shelf-life) were analyzed. Both SA and MeJA treatments, irrespective of application method, reduced weight, firmness, and colour losses compared to the control. Treated fruits also showed better colour retention, with irrigation showing superior hue angle values. The phytohormones modulated postharvest ripening, increasing total acidity after 28 days. Notably, preharvest applications, especially SA applied via irrigation, significantly mitigated the CI incidence. This protection was linked to enhanced non-enzymatic antioxidant systems, including increased total phenolic content (TPC), hydrophilic-total antioxidant activity (H-TAA), lipophilic-total antioxidant activity (LTAA) and total carotenoid content (TCC). The study also revealed that the irrigation application of SA reduced saturated fatty acid (SFA) content, while MeJA irrigation decreased specific SFA and increased unsaturated fatty acid (UFA) content. Thus, SA irrigation resulted in the highest UFA/SFA ratio. In conclusion, preharvest applications of SA and MeJA modulated antioxidant and lipid metabolism, improving postharvest quality and enhancing chilling tolerance. Irrigation with 0.5 mM SA proved most effective, demonstrating its potential for commercial application to enhance green pepper storability and health benefits. Finally, this research provides valuable insights into the physiological effects of these phytohormones on green pepper fruit.