A Comparative Study of Phenolics in Green Husks of Selected Hungarian Walnut Cultivars

DW, with significantly higher values in the warmest year, 2024, and in cultivar Esterhazy kései compared with Chandler. Across cultivars and years, phenolic levels were generally elevated at early lignification (S1, BBCH 73-75) and at full maturity (S5-S6, BBCH 87-88), with depressed concentrations during mid-fruit development (S2-S4, BBCH 77-86). Several hydroxycinnamic acids, flavonoids, and naphthoquinones showed cultivar-specific and year-dependent patterns. Thermal conditions (cumulative GDDs) explained a substantial proportion of residual variation in TPC. These results highlight the combined roles of genotype, seasonal climate, and developmental stage dependencies in biosynthetic processes of phenolics in walnut green husks despite the diversity in factor effects.