Germination Responses of Taraxacum platycarpum Seeds to Temperature

概要

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Germination responses of Taraxacum platycarpum seeds to temperature were examined under laboratory conditions to investigate the emergence-season choice mechanism of the seeds. Almost all the newly collected seeds were non-dormant. Under constant temperature conditions, maximum percentage germination (approximately 90%) was attained at temperatures 6-16℃, where simple linear relationships were observed between the temperature and the rates of germination, i. e. the reciprocals of the time taken to germinate by seed subpopulations with 10-80% germination. Thermal time required for germination of the subpopulations ranged from 600 Kh (degree Kelvin×hours) to 1500 Kh with a relatively constant base temperature of about 2.5℃. Lower limit temperature for germination was slightly below 6℃. Higher limit temperature for germination has the normal distribution with the mean ± SD of 19±2.5℃. Pre-exposure of imbibed seeds to temperatures higher than the higher limit temperature for germination, 25 and 30℃, had no effect on the germinability and the rate of germination at a circa-optimum temperature. Moist chilling treatment at 4℃ caused an increase in the variation of germination rate within the seed population, but no evidence for dormancy-inducing or breaking effects was obtained.
種生物学会の論文
1989-12-30