Abstract
In previous studies, seeds of Weigela hortensis K. Koch had high germination rates in light but did not germinate or only germinated less than a few percent in darkness, even after cold stratification. However, those studies were conducted under experimental conditions in relatively narrow range. If we can work out how to germinate seeds of W. hortensis in darkness, we can germinate them in soil and thus improve the rate of germination in seedling works to cover slopes. Therefore, we tested a broader range of temperatures and stratification treatments in this study than in previous studies and confirmed the results of those studies. We also tested the effects of temperature, stratification, light irradiation in detail, and GA3 on germination in darkness, which have not hitherto been reported. Germination in darkness was optimized by cold stratification at 5 to 10℃ for ≥15 days and then irradiation at ≥7 μmol • m-2 • s-1 for 1 to 2 days at 25 to 30℃. With this treatment, even seeds stored at room temperature without desiccant for 401 days had an 80% germination rate at 20 to 30℃ in darkness. However, seeds cold-stratified, irradiated by such methods, and then stored moist at 5℃ in darkness for ≥ 3 days decreased subsequent germination at 25℃ in darkness.
