摘要
In many wild species, seeds are dormancy at maturity and will not germinate even under favorable environment conditions. Dormancy is a complex trail that is determined by many factors. Some studies have shown that cold stratification and the application of gibberellic acid (GA) can break seed dormancy and promote seed germination. The present study investigated the causes of plant dormancy and the effect of cold stratification and different concentrations of exogenous GA<sub>3</sub> in regulating Cephalotaxus sinensis seed germination. Results showed that C. Sinensis seeds have good water permeability, which suggested that seed coats were not the main cause that inhibited the seed germination. There were germination inhibitions in all parts of seeds, and the order of inhibitory effect was: testa < endosperm (embryo), which indicated that existence of germination inhibitions was the main reason causing seed dormancy. Endogenous GAs and IAA (indole-3-acetic acid) content increased, while ABA (abscisic acid) content decreased over the experiments. ZR (zeatin riboside) content decreased in the early phase of cold stratification, but rebounded by the end of the experimental period. The changes of endogenous hormone indicated that GA, IAA and ZR played a positive role in seed germination, whereas ABA was associated with seed dormancy. Besides, the relative ratio of GA/ABA, IAA/ABA and ZR/ABA may play a more important role than their absolute level during the seed development.
In many wild species, seeds are dormancy at maturity and will not germinate even under favorable environment conditions. Dormancy is a complex trail that is determined by many factors. Some studies have shown that cold stratification and the application of gibberellic acid (GA) can break seed dormancy and promote seed germination. The present study investigated the causes of plant dormancy and the effect of cold stratification and different concentrations of exogenous GA<sub>3</sub> in regulating Cephalotaxus sinensis seed germination. Results showed that C. Sinensis seeds have good water permeability, which suggested that seed coats were not the main cause that inhibited the seed germination. There were germination inhibitions in all parts of seeds, and the order of inhibitory effect was: testa < endosperm (embryo), which indicated that existence of germination inhibitions was the main reason causing seed dormancy. Endogenous GAs and IAA (indole-3-acetic acid) content increased, while ABA (abscisic acid) content decreased over the experiments. ZR (zeatin riboside) content decreased in the early phase of cold stratification, but rebounded by the end of the experimental period. The changes of endogenous hormone indicated that GA, IAA and ZR played a positive role in seed germination, whereas ABA was associated with seed dormancy. Besides, the relative ratio of GA/ABA, IAA/ABA and ZR/ABA may play a more important role than their absolute level during the seed development.
