Effects of Fruit Maturity Stage and Seed Storage Conditions on Germination and Endogenous ABA and GA Levels in Solanum torvum

Abstract

Solanum torvum is an important medicinal and culinary vegetable with poor seed propagation, characterized by low germination and limited seed longevity. This study examined the effects of fruit maturity stage, storage temperature, duration, and endogenous hormonal profiles on seed germination. Fruits were harvested at three physiological maturity stages: matured green, ripe yellow, and overripe brown. Extracted seeds were stored in ambient (24–26 °C) and cold (3–8 °C) conditions for 24 weeks, with subsequent germination testing with 3 replicates per treatment. Endogenous abscisic acid (ABA) and gibberellic acid (GA) were quantified using HPLC-DAD to assess their association with germination behaviour. Seeds from ripe yellow fruits achieved the highest germination (95%), with a mean germination time of 12 days and a mean germination rate of 8%, identifying this stage as the optimal maturity stage for harvest. While total germination percentage was enhanced by an after-ripening effect during the first 16 weeks of ambient storage, other vigour parameters, including mean germination time and rate and synchronization began to decline thereafter. ABA and GA concentrations displayed treatment-dependent variation across maturity stages and storage conditions, with hormonal trends showing complex associations with dormancy release rather than consistent main effects. These findings indicate that harvesting Solanum torvum fruits at the ripe yellow stage and storing seeds under ambient conditions for up to 16 weeks, under the conditions evaluated in this study, provides a practical balance between dormancy alleviation and seed vigour, thereby improving short-term propagation efficiency.