Abstract
Soybean cv. "Miyagishirome" (flat type) was planted to use or not use light efficiency (Type R or Type P). This study was conducted to research the effect of light utilization of canopy on leaf nitrogen concentration and accumulation, nitrogen distribution in each canopy, and nitrogen partitioning into the pod. Leaf nitrogen concentration increased and showed the highest level in Type R with 25 plants m-2. After R2, leaf nitorogen concentration decreased sharply in Type R and gradually in Type P. Total nitrogen accumulation increased higher in Type R than in Type P from the early reproductive stage. Leaf and stem nitrogen accumulation increased in Type R, but only leaf one did in Type P at R5. Nitrogen accumulation in vegetative organs contributed to the amount of nitrogen partitioning into the pod after R5. Leaf nitrogen accumulation distributed into higher layers of canopy and declined gradually to the ground in all treatments. But the concentration level in leaf nitorogen was higher in Type R than in Type P at low layers and it showed high photosynthetic ability because of more light penetration at R6. From these results, light intercepting characteristics that related with photosynthesis at reproductifve stage ware suggested to effect on nitrogen concentration in leaf. Nitorgen accumulation in vegetative organs contributed to increase nitrogen partitioning into the pod. Nitrogen partitioning from leaf and stem was higher in Type R.
