The Effect of Alternative Nutrient Supplements on Histological Traits and Postharvest Water Loss in Pepper Fruit

Postharvest water loss critically determines the shelf life and quality of pepper fruits. This study investigated how three alternative soil amendments—rhyolite tuff (RT), composted and pelletized poultry litter (CPPL), and clarifying agent (CA)—affect water loss, structural traits, and their interrelationships across three ripening stages (immature, mature, and overripe) in the Hungarian wax pepper cultivar ‘Tizenegyes’. A completely randomized design (CRD) was applied in a small-plot field experiment. Macro- and micromorphometrical analyses included pericarp, cuticle, epidermis, collenchyma, hypodermis, parenchyma, and endocarp thickness; fruit fresh weight; surface area; and the surface area-to-weight ratio (SA/W). Daily weight measurements were used to quantify water loss, while cuticle function was assessed by comparing wax-removed and intact fruits. The water loss rate (WLR) was strongly influenced by pericarp tissue structure—particularly cuticle thickness, hypodermal cell layer number and thickness, and collenchyma cell wall thickness—as well as fruit size at ripening stage. Among treatments, RT was the most effective in reducing postharvest water loss and extending fruit shelf life. Fruits from the control plots lost 26% more water than RT samples, 12.8% more than CPPL, and 14.2% more than CA. Although RT-treated fruits were smaller, they had thicker pericarp and hypodermis layers, more collenchymatous cell rows, and thicker cell walls, all of which contributed to lower water loss and prolonged freshness. These findings highlight RT as a promising alternative nutrient source for sustainable pepper production, with significant potential to improve postharvest quality.