水稻光週期的研究7.——夜間溫度對於光週誘導的影響

Photoperiodic studies on rice VII. The effect of night temperature on photoperiodic induction

1. Three daylength sensitive rice varieties, Shinriki, Shuang-chiang and Wan-tze were subject to the short day treatment of 9L+15D. During the 15D period, they were placed at the following temperature levels: 15°, 20°, 24°, 28° and 32°C. It was found that all three varieties failed to head at the night temperature of 15°C. The optimum night temperature was 24° up to 28°C for Shinriki and 28°C for Shung-chiang and Wan-tze. At temperatures lower or higher than the above, heading was delayed. 2. A daylength insensitive variety Norin No. 11 with a very short growth period was subject to the following night temperature level: 15°, 20°, 24°, 28°, 32° and 34°C. It was found that low temperatures suppressed floral bud initiation and the growth of floral buds already initiated. However, there was still heading at 15°C. 3. The authors express doubts about the temperature sensitivity indicators of rive varieties as suggested by Japanese investigators.