Trait-based and multivariate evidence of complementary roles of wood vinegar and mineral fertilization in bell pepper yield and fruit morphology

Abstract The integration of biostimulants with mineral fertilization can improve productivity, yet how these inputs interact to shape yield formation and fruit morphology in bell pepper remains poorly understood. This study applied a trait-based and multivariate framework to evaluate the effects of wood vinegar (WV) and mineral fertilization on phenology, yield components, and fruit morphological traits of bell pepper under controlled pot conditions. Five treatments were evaluated: control, WV alone, inorganic fertilizer at the recommended rate, and WV combined with fertilizer at 50% below or above the recommended rate. Combined WV and fertilizer applications advanced flowering by 4–5 days relative to the control. Mineral fertilizer alone maximized fruit number (4.34 fruits plant⁻ 1 ), whereas WV alone increased individual fruit weight (7.43 g fruit⁻ 1 ). The highest marketable yields were achieved under WV combined with fertilizer at both reduced and elevated rates (20.52–22.12 g plant⁻ 1 ), representing a 53–65% increase over the control. These treatments also produced larger and more uniform fruits, with increased fruit length, width, and estimated volume, alongside a reduced fruit shape index indicative of blockier, market-preferred morphology. Correlation and regression analyses identified marketable fruit weight, fruit number, and fruit width as the primary determinants of yield, while delayed flowering and non-marketable biomass were negatively associated with productivity. Principal component analysis further demonstrated that integrated WV and mineral fertilization reorganized trait relationships toward improved fruit filling, volume, and yield. Overall, the results indicate that wood vinegar complements mineral fertilization by enhancing yield efficiency and fruit quality in bell pepper.