Association of abscisic acid and gibberellins with dormancy and germination in seeds of Prunus buergeriana Miq.

Freshly harvested seeds of Prunus buergeriana Miq. are dormant and have poor germination. Moist stratification of seeds at 4℃ for 12 wk or treating seeds with a 500-ppm GA3 solution promoted germination, but the mean germination time with the latter was about 40 d longer than that of the former, indicating that the germination rate of the latter was slow. Concentrations of abscisic acid (ABA) and gibberellins (GAs) were measured by GC-MS-SIM in fresh seeds, warm- or cold-stratified seeds, and germinating seeds. Fresh seeds contained a higher concentration of ABA of 476 ng (g DW)-1, but the concentration of ABA declined to 20-times lower after warm or cold stratification and was close to that of germinating seeds. Cold stratification at 4℃ increased the endogenous GA1, GA3, GA4, and precursor GA20, among which GA1, GA3, and GA20 showed greater increases. Warm stratification decreased the ABA content of seeds, but the seeds still did not germinate. Cold stratification not only decreased the ABA content but also increased the GA contents. We concluded that ABA is implicated in the regulation of seed dormancy, but the initiation of seed germination is more dependent on GAs.