大豆光合生理生态的研究：第13报 大豆叶片的光合速率和水分利用效率

大豆叶片的水分利用效率明显随生育期进程而变化。大体上从幼苗期到结荚期较低,而初生叶及鼓粒期、黄叶期叶片较高。光合速率随生育期进程呈单峰曲线变化,以鼓粒期最高。生殖生长期间水分利用效率的日变化是早晚较高,9:00～15:00较低且变化平缓。不同层次叶片水分利用效率,在结荚鼓粒期自而下依次增高,开花期无明显差异。

THE PHOTOSYNTHETIC RATE AND WATER USE EFFICIENCY OF SOYBEAN LEAF

The water use efficiencys (WUE) of soybean leaves changed obviously in different growth stages. WUE was lower from Vs to R3_4 stages and higher in V1, R5-6, and R 7-8 stages. The changes of leaf photosynthetic rates showed a single peak curve during the whole growth stages and the highest value occured in R5-6. The duirnal change of water use efficiency during reproductive stages was relatively higher in the early morning and later afternoon, but it was relatively lower from 9:00 to 15:00 and varied gently. In R3-R6 stages the value of water use efficiency increased from the leaves at upper nodes to the leaves at lower ones. There was no difference in water use efficiency during R1-2 while the difference was greater in podsetting and podfilling stages than that in the other ones.There were difference in water use efficiency among different cultivars. The old cultivars showed higher water use efficiency in vegetative stages but lower in reproductive stages than the new ones. So it was suggested that higher water use efficiency in reproductive stages may be better to the growth of soybean seed.