Abstract
It was reported in previous papers that the effect of shading treatment on photosynthetic rate (Pn) showed a differentiated growth stage. The present study was carried out in multiple regression analysis in order to determine the cause. The multiple regresion analysis showed that SLA was highly negative and leaf N% was positive in the period of flowering. For shading treatment at the pod formation, N% in leaf, SLA and leaf water potential (Wp) showed a higher correlation coefficient at r=0.818^<**>. The Pn was significantly correlated with N% in leaf of shaded and non-shaded plant at all shading treatments. The Pn in the treated plant was higher than in the control plant due to higher N% in the leaf. The shading treatment at maturity, stomatal conductance (Sc) decreased by 0.5cm/sec. An increase of Sc and Pn due to higher N% in the leaf by shading treatment was observed.
