Requirements for seed germination and non-deep simple morphophysiological dormancy in Sandersonia aurantiaca (Colchicaceae)

摘要

Seed germination in Sandersonia aurantiaca is unstable and the requirements for germination are still unclear. We investigated requirements for germination using a broad range of treatments. The small embryos of S. aurantiaca seeds suggest morphophysiological dormancy(MPD),thus we also examined MPD levels in S. aurantiaca seeds. Radicles emerged from 18.8% of seeds without seed coat in light condition. In contrast,95% of the seeds incubated in darkness produced radicles. In darkness,radicles emerged from only 1.3% of seeds with seed coat and from 60% of seeds without seed coat. In seeds without seed coat incubated in darkness,radicles emerged from 30% of seeds incubated at 30/20°C (alternating temperature)following a low temperature(cold stratification)at 5°C, but not from seeds at 35/25,25,or 30°C following at 5 or 10°C. In seeds without seed coat incubated in darkness,regarding the effect of low temperatures(5°C and 10°C)before high temperatures,radicle emergence seemed to be higher in 5°C treatments than 10°C. These results indicate that S. aurantiaca seeds require removal of the seed coat,incubation in darkness,and low temperature to germinate. Radicles emerged,on average,from 40-70% of seeds without seed coat incubated in darkness at 5°C for 90 days followed by at 30/20°C. Furthermore, low temperature was required for embryo growth and radicle emergence at subsequent high temperature. Shoots emerged from more than 80% of the seeds with radicles at 30/20°C and at 20°C or more. These show that seeds of S. aurantiaca have non-deep simple morphophysiological dormancy.