Genotype-Dependent Effects of Soil Conditioners on Pericarp Structure and Postharvest Water Loss in Sweet Pepper (Capsicum annuum L.)

Postharvest water loss in pepper (Capsicum annuum L.) is largely determined by the pericarp tissue structure. This study investigated the effects of three soil conditioners: rhyolite tuff (RT), composted and pelletized poultry litter (CPPL), and a clarifying agent (CA) on fruit microanatomy and 14-day water loss dynamics (using intact and cuticle-removed fruits) in technologically mature Capsicum annuum L. ‘Tizenegyes’ and biologically mature ‘Csángó F1’ peppers. The results were analyzed using one-way analysis of variance (ANOVA), followed by Tukey’s post hoc test, Pearson correlation analysis, principal component analysis (PCA), and partial least squares discriminant analysis (PLS-DA). The treatments significantly reduced water loss but induced distinct tissue-level adaptations. ‘Tizenegyes’ exhibited a hypodermis-centered response (VIP = 1.22); RT increased collenchyma and parenchyma thickness, reducing water loss by 25.7%. Moreover, RT-treated fruits remained highly resistant to water loss even after cuticle removal, showing only a 2.5% increase. In contrast, ‘Csángó F1’ responded through coordinated structural rearrangements across the entire pericarp. Although CPPL reduced cuticle thickness by 48.7% in ‘Csángó F1’, the CA treatment provided the most stable physiological performance and consistently low water loss in both genotypes. These findings demonstrate that soil conditioning is an effective strategy for improving postharvest quality. Water retention depends not only on cuticle thickness but also on genotype-specific tissue adaptations, particularly the reinforcement of the hypodermis and its collenchyma.