Single Leaf Photosynthesis of Rice Plants under Field Conditions : IV. Variation in single-leaf photosynthesis among several successive days, and the interactive effects of irradiance and stomatal conductance on CER

[摘要] (1) Variations in single-leaf photosynthesis (CER) among days: CER under saturation light intensity at nearly the same time of several successive days were examined, at three growth stages. (i) CER varied from day to day. The difference between the maximum and the minimum for the several successive days amounted to 5-10 mg CO2 dm-2 h-1. (ii) The variations in CER among days were positively correlated with those in stomatal conductance (gs). (iii) The variations in gs was negatively correlated with those in the current evaporation rate evaluated witll a Piche's evaporimeter. (iv) From the above, it was concluded that the variations in CER were brought about by climatic factors such as radiation intensity, wind speed and air humidity, which affect stomatal aperture through waterloss from leaf tissues or a direct effect on stomata. (2) Interactive effect of irradiance and stomatal conductance on CER: The data collected on several successive days at various times of day and under various weather conditions were combined. Then, they were placed into seven groups according to magnitude of gs, and light-CER relationships were examined considering the levels of gs. (i) Under low light intensity, there was little difference in CER irrespective of magnitude of gs. (ii) The light saturation point rose with an increase in gs. (iii) Under strong light intensity, CER was shown to depend on gs and increased with an increase of the latter.

[学科分类] 农业科学（综合）

[关键词] Evaporation rate;光飽和点;Light intensity at the leaf surface;蒸発速度;Light saturation point;気孔伝導度;Rice plants;個葉光合成;Single-leaf photosynthesis;水稲;stomatal conductance;葉面光強度