Studies on Yield Forecast in Main Crops : VI. On the relation between nitrogen content in leaves and photosynthetic ability of rice plant at ripening stage

Abstract

Photosynthetic ability of rice plant at ripening stage had an intimate correlation with nitrogen content in leaves. Accordingly, in general cases, it is assumed to be beneficial for the photosynthetic ability of the rice plant to maintain nitrogen content in leaf blades at a relatively higher level. During the ripening stage, the decreasing nitrogen content in leaves was mainly due to the translocation of nitrogen in leaves to the ear, associated with the carbohydrates transport from the vegetative parts to the ear. The nitrogen content in leaves could be maintained at high level during the ripening stage by the treatments, i. e., the restriction in number of glumes and the removing of the ear, but the photosynthetic ability and the net assimilation ratio of the treated plant were lower than the non-treated plants. These results suggest that the photosynthetic ability of the rice plant at the ripening stage may be materially influenced through the degree of translocation of photosyntheates from the vegetative parts.