Abstract: The obvious effects of twilight on two photoperiod reactions in HPGMP was presented. Its main reaction may be that effective light-length is prolonged.If the twilight would be covered in the first photoperiod reaction of HPGMR,the spikelet primordium initiation and heading will be accel- erated. When the natural light-length is near the critical value in the secondary photoperiod reaction, if the twilight would be covered,the poliens might be changed from sterility to fertility, and the process of spikelet primordium initiation was accelerated. But the sterile pollen might be induced,if morning twilight had not been covered.It indicated that the morning twilight is more intensive and its effect more obvious than twilight. Authors put forward a new opinion that a day should be divided into “day”and“night” by “light-length” (containing day-length and the effective twilight)may be more accurate than by “day-length”。

Key words: Hubei Photoperiod-sensitive Genic Male-sterile Rice(HPGMR), Twilight, Photoperiod reaction, Fertility change

摘要： 本文论证了曙暮光在光敏感核不育水稻两个光周期反应中均有明显的作用,初步探明农垦58S 在武汉地区(30°27′N)育性转换期(7—8月)曙暮光的变化规律,提出采用“光照长度”以代替“日照长度”来划分光周期的昼与夜更为准确的见解,据此讨论了曙暮光的作用对光敏感核不育水稻在不同地理条件下的生态适应性的重要影响。

关键词: 光敏感核不育水稻, 曙暮光, 光周期反应