Abstract: Using Yuanfengzao, 837 and other rice varities as materials, we have made numerous studies from 1986 to 1990 concerning the daily changes of photosynthesis in rice and theit relation with the interior and exterior elements. The daily changes of photosynthesis in rice show a kind of double-peaks’ curve. The changes of stomotal opening wasalmost synchronous with the daily changes of photosynthesis. Watering or spraying solutions of P and K on leaves candecrease the degree of afternoon nap, but can’t eliminate the phenomenon. Delayed, counter-photoperiod or all dayand night lighting can’t change the original rhythm. However, when the time of the treatment is over several days, theoriginal rhythm disappeared and the new rhythm that adapts to the new condition is created. It suggested that the dailychanges of photosynthesis in rice are not only influenced by the external condition of temperature, light, water and atmosphere. but also have relation with the internal rhythm’s regulation.

Key words: Afternoon nap, Daily changes of photosynthesis, Original rhythm

摘要： 1986-1990年以水稻原丰早、837等为材料研究了水稻的光合日变化及其与内外因素的关系。水稻的光合日变化呈典型的双峰曲线。光合日变化与气孔开度日变化基本上是同步的。叶面喷水和磷、钾溶液，可减缓光合午睡的程度，但未见午睡消失。延迟见光，短时间的反光周期处理或全光照处理，不改变光合日变化原有的时间节奏。长时间反光周期或全日照处理，则适应形成新的光合日变化规律。说明水稻光合日变化与内生节奏的调节有关。

关键词: 光合日变化, 内生节奏, 水稻