Physiological factors affecting purple passion fruit (<i>Passiflora edulis</i> f. <i>edulis</i>) post-storage seed germination

Passiflora edulis f. edulis is recognised as an important tropical and subtropical fruit with cold resistance and desirable flavor. The relationship between seed storage and germination remains unclear. This study evaluated the germination characteristics, antioxidant enzyme activity, and hormone contents of purple passion fruit seeds stored at 20 ± 5°C for up to three years. The moisture content of the seeds varied between 8.3 and 8.9%, with both water absorption and germination percentage significantly decreasing over time. the seeds underwent considerable peroxidation reactions during storage, while auxin (IAA), zeaxanthin (ZT), gibberellin (GA), abscisic Acid (ABA), jasmonates (JA) and salicylic acid (SA) remained low at the third year. Overall, storage negatively impacts germination of purple passion fruit seeds. Reduced water absorption and low hormone levels, particularly gibberellin, may critically inhibit cellular activity. Friction can be employed to disrupt the outer seed coat and enhance water absorption. Alternatively, the application of exogenous gibberellic acid may alter the balance of hormone metabolism and improve germination percentage. It is recommended that for breeding using purple passion fruit as a parent, a simultaneous harvesting and sowing method may increase the yield of hybrid offspring.