Postharvest quality and nutrient contents of long sweet pepper enhanced by supplementary potassium foliar application

Abstract

Inadequate amounts of potassium uptake by plant roots, even if it is available in soil, can be due to soil pH, plant type, and plant growth stage. Quality and shelf-life of long sweet pepper (Capsicum annuum L.) are affected by plant nutrition. To determine the suitable potassium source for foliar fertilization during plant growth, effects of supplementary foliar K sources (K-humate, KCl, and K <inf>2</inf> SO <inf>4</inf> ) were evaluated on fruit quality, chemical composition, and postharvest behavior of long sweet pepper. Pepper fruit were stored for 28 days at 10°C. Fruit weight loss and decay were reduced, and total soluble solids were increased by supplementary K application; K <inf>2</inf> SO <inf>4</inf> and KCl were the most effective sources. The L* and chrome values, as indicator for surface color, were enhanced by K foliar fertilizer. Chlorophyll a and b were increased by K treatments compared to control. Carotenoids were increased by KCl treatment; K <inf>2</inf> SO <inf>4</inf> was the most effective source for enhanced total phenols. Total sugar and vitamin C were increased by K application, especially when K was added as KCl. Nitrogen and phosphorous contents in fruit were enhanced by K-humate and KCl treatments while potassium content was enhanced by all K treatments. The K <inf>2</inf> SO <inf>4</inf> and KCl could be suitable K sources for foliar fertilizer during plant growth to enhance growth, yield, and quality of pepper fruit.