夏大豆群体光合特性的研究

本文研究了夏大豆的群体光合特性。结果表明，夏大豆群体内光强自上而下逐渐减弱，群体光合随光减弱而明显下降。开花结荚期一天中，１３时群体光合速率达最大值。在一定范围内，密度大的光合速率在上午上升得快，峰值持续的时间长，对早，晚的弱光利用率较高。音以前和１９时以后，各群体的光合速率均为负值。分枝期的群体光合速率主要决定于种植密度。开花结荚期的群体光合速率与种植密度呈抛物线关系，与百粒重，生物产量和籽粒产

STUDY ON THE PHOTOSYNTHETIC CHARACTERS OF SUMMER SOYBEAN CANOPY

The photosynthetic characteristics of the sudmer soybean canopy were studied. The results showed that light intensity inside the summer soybean canopy decreased from the top of the canopy to the ground. Also,the canopy apparent photosynthetic rate (CAP) strongly decreased with the weakness of the light intensity. Cap reached its ark at 13:00 p.m.at the flowering and pod -setting stage(R3).Within a certain range,CAP of the larger population canopy lrises more quickly in the early morning and its peak lasted for a longer time.Also,the larser population canopy had a better use of the weak light in the early morning and the late afternoon.At the branching stage (V5),CAP is mainly influenced by the plant density.At the flowering and podsetting stage (R3),CAP is parabolicly related to the plant density;there is a significant or very significant relationship between CAP and the weight per 100 eds as well as biological yield.To increase the reasonable plant density and to enhance CAP and prolong the canopy photosynthetic time durins the flowering and pod-setting stage(R3)as well as after the stage are essential to increase yield of summer soybean.