メヒシバ属植物の生理生態(第1報) : メヒシバの発芽と温度
摘要
1. Studies have been made in the effect of temperature upon the germination of seeds of Digitaria sanguinalis Scop. var. ciliaris Doell. 2. It was determined that the optimum temperature for the germination of seeds which had been kept for about 550 days in dry storage after the harvest was between 30° and 35℃, 15°～20℃, the minimum and 40°～45℃, the maximum. 3. No definite effect on the vitality of the seeds was seen when they were stored in a dry state for 200 days at 40℃, or for two weeks at 55℃ ; but storage of wet seeds at 45℃ for about 10 days, or at 55℃ for a day caused them to fail to germinate. 4. T he seeds which has ripened in September laid dormant in a natural condition until April of the following year. 5. During the period of dormancy t h ere was no germination at a constant temperature ; but as the seeds aged in dry storage the rate of germination gradually increased. About the middle of May, of the seeds which had been kept for 200 days in dry storage after the harvest, a few germinatied at a constant temperature. Then by the latter part of September, about 1-year after the harvest, germination started promptly and the germination percentage became 50 % within 7 days after the sowing. However, there was no increase in the germination percentage during later days. 6. Daily alternating temperatures we r e effective in prompting the germination of dormant seeds. 7. The seeds which had been kept for about 260 days in dry storage after the harvest, were kept in seven sets of daily alternating temperature, namely 10° to 25°, 10° to 30°, 10° to 35°, 10° to 40°, 25° to 45°, 25° to 40°, 30° to 40°. They were kept in high temperature for a longer time than low temperature, and it was found that the set 21 hours in high temperature (35° or 40°) and 3 hours in low temperature (10℃) was most effective for the germination. 8. Yellow ripened seeds (meaning fully ripe) failed to germinate when they were sown immediately after the harvest under constant temperature. N