Preharvest application of naphthalene acetic acid and kelpak® improve postharvest quality and phytonutrient contents of sweet pepper

Abstract

ABSTRACTPreharvest application of plant growth regulators may have promise to improve product shelf-life. The study examined effects of the plant growth regulators [naphthalene acetic acid (NAA), the seaweed concentrate Kelpak®, and their combination] on postharvest quality of yellow sweet pepper (Capsicum annuum L.) grown in soilless culture. Seedling root plugs were soaked in Kelpak® at 10 mL∙L−1, 3 h before transplanting. Thereafter, solutions applied to foliage until runoff were: NAA at 20 mg∙L−1 and Kelpak® at 5 mL∙L−1 at 15, 30 and 45 days after transplanting. Sweet peppers were harvested at maturity, and stored at 7.5ºC for 0, 7, 14, or 21 days (d). The individual Kelpak® and NAA applications minimized weight loss and color degradation during storage. All treatments helped retain firmness and tissues had higher pH compared to the control. Application of NAA+Kelpak® favored accumulation and retention of total soluble solids until 14 d of storage. Fruit treated with Kelpak® and NAA+Kelpak® had higher ascorbic acid content than all other treatments. Application of NAA+Kelpak® helped retain higher carotenoid content. The NAA, Kelpak®, and their combination, enhanced accumulation of total phenols over time with minimal impact on antioxidant power (FRAP activity). The NAA and Kelpak® preharvest application can improve quality of yellow sweet pepper during postharvest storage up to 7 d.