Relationship between the change in the chloroplastic nitrogen fractions and the rate of oxygen evolution in rice plants

Chloroplasts and the lamellae systems were isolated from rice leaves and the change with leaf age in the nitrogen fractions localized in the lamellae systems and the stroma region was examined. The pattern of the change in these two chloroplastic nitrogen fractions varied according to the leaf position. In order to find out the relationship between the change in the chloroplastic nitrogen fractions and the photosynthetic activity of a leaf, the rate of oxygen evolution of leaf sections on a total leaf nitrogen basia was also followed. The rate of oxygen evolution/total leaf nitrogen was affected by two factors. i.e., lamellae nitrogen/total leaf nitrogen and the lamellae-stroma composition of the chloroplast. An increase in lamellae nitrogen/total leaf nitrogen caused an increase in oxygen evolution, whereas an increaae in the proportion of stroma nitrogen in chloroplast brought about the negative effect. Consequently, oxygen evolution/total leaf nitrogen had a close correlation with an index of lamellae nitrogen²/total leaf nitrogen × chloroplast nitrogen. The relationship with the photosynthetic efficiency of the leaf nitrogen is also discussed.