Germination Performance and Longevity Prediction of Weigela subsessilis (Nakai) L.H.Bailey, an Endemic Plant of Korea, under Long-Term Storage

Abstract

This study evaluated the germination characteristics and predicted longevity of Weigela subsessilis, an endemic plant in Korea, under long-term seed bank storage. Seeds from 16 accessions were stored at –18 °C for 0, 5, 10, and 20 years, and their germination performance was assessed. The initial germination percentage (78.75%) remained stable after five years (79.67%) but declined significantly after ten years (62.90%). Two accessions tested after 20 years showed a steep reduction to 14.86%. MGT and T50 were stable, GI increased slightly, but PV and GV declined, suggesting dormancy release alongside reduced vigor. Seed longevity was predicted using Probit analysisThe estimated initial viability (K ) was 1.15, with a slope of –0.092, yielding a predicted Pi50 of 12.5 years (95% CI: 11.2–13.8 years). The confidence interval broadened with longer extrapolations, underscoring the uncertainty of projections beyond 15–20 years where empirical data remain limited. These results provide the first empirical evidence of viability decline in W. subsessilis seeds over two decades of storage. They highlight the need for systematic monitoring in seed banks, with testing recommended at five-year intervals beyond ten years of storage. Regeneration or recollection strategies should also be implemented as viability approaches critical thresholds. This study offers essential baseline data for developing conservation strategies for Korean endemic species and contributes to the sustainable management of native plant genetic resources.