Seasonal climatic variation is associated with persimmon (Diospyros kaki) leaf flavonoid peaks and tannin indices

Persimmon ( Diospyros kaki ) leaves are a valuable resource for medicinal, beverage, and cosmetics industries, with flavonoids and tannins as key bioactive constituents. This study evaluated how seasonality, genotype, geographic origin, and cultivation conditions influence their accumulation in leaves from four genotypes across three South Korean regions, grown under greenhouse and open-field conditions. Persimmon leaf extracts were profiled by HPLC–DAD for nine flavonoid-related peaks, alongside polymeric (PTC) and nonpolymeric tannin (nonPTC) quantification. Flavonoid-related peaks and tannin indices varied across sampling months and showed inverse associations with climatic parameters, with the highest levels observed in May, October, and April for flavonoid-related peaks, PTC, and nonPTC, respectively. Cultivation-condition effects were limited at the individual peak level, although specific variables showed significant responses and August-to-October changes suggested cultivation-associated temporal responsiveness in summed flavonoid-related peaks and tannin fractions. Genotype and geographic origin showed limited effects on most selected features, except for nonPTC. Overall, this study provides useful information for optimizing harvest timing and improving standardization strategies for persimmon leaf raw materials.