Seed dormancy and germination in Sophora secundiflora (Fabaceae)

Given the ecological and horticultural significance of Sophora secundiflora (Ortega) DC., effective dormancy-breaking techniques are crucial for enhancing its cultivation and ensuring successful establishment in both natural and managed environments. Seeds have an extremely hard and water impermeable testa. This study evaluated the effects of mechanical scarification (MS), sulphuric acid (SA) soaking for 30, 60, and 90 minutes, and hydrogen peroxide (HP) soaking for 10 and 20 minutes on final germination percentage (FGP), mean germination time (MGT), time to 50% germination (T50), and coefficient of velocity of germination (CVG). Mechanical scarification and 60-minute sulphuric acid treatments were the most effective, achieving FGPs of 95% and 93%, respectively, and showing efficient germination processes as indicated by T50 and CVG metrics. Mechanical scarification resulted in the fastest and most consistent germination. Sulphuric acid treatments showed time-dependent efficacy, with the 60-min treatment optimizing both germination speed and percentage, whereas the 90-min treatment caused potential seed damage, reflected in a lower FGP. Hydrogen peroxide treatments were less effective overall, with a maximum FGP of 33% for the 20-minute soaking. Statistical analysis highlighted significant differences among treatments, particularly for FGP (p < 0.0001), T50 (p = 0.0020), and CVG (p = 0.0348). These findings align with existing research on Fabaceae species, supporting the importance of physical and chemical scarification methods in breaking seed dormancy. This study provides critical insights into optimizing germination protocols for S. secundiflora, with wider applications for other hard-seeded Fabaceae species.