Studies on the Photosynthesis and Dry Matter Production of Rice Plants : II. Varietal differences in the relationship between the content of nitrogenous constituents in the leaf and photosynthetic activity induced by nitrogen topdressing

[摘要] An investigation was carried out concerning the relationships between changes in the content of nitrogenous constituents in the leaf and its photosynthetic activity caused by nitrogen topdressing given at ear-formation or at heading, using four varieties, Tongil, Milyang 23, Kochihibiki and T-136. 1. Photosynthetic activity was higher in the indica-japonica hybrid varieties than in the japonica or the indica, with further increase by nitrogenous topdressing. 2. The content of total nitrogen, soluble proteins and Fraction 1 protein was higher in the indica-japonica hybrids than in T-136 and Kochihibiki, with further increase by nitrogen topdressing. 3. Changes in the photosynthetic activity showed a linear correlation of wide range with total nitrogen content, but a curvilinear correlation with the content of soluble proteins or Fraction 1 protein, giving a tendency to saturate at higher contents. In this case, the indica-japonica hybrids needed higher content to reach saturation, giving higher photosynthetic activity than the indica or the japonica. 4. In T-136 photosynthetic activity was positively correlated with total nitrogen content, but not so with the content of soluble proteins or Fraction 1 protein. 5. Considering these results, it was supposed that at least two factors, one, the Fraction 1 protein content and the other, something that changed in proportion to the total nitrogen content, were responsible for the changes in photosynthetic activity by nitrogen topdressing. 6. The higher productivity of the indica-japonica hybrids may be attributable to the greater responsiveness of their photosynthesis and of yield capacity to additional nitrogen fertilization.

[学科分类] 农业科学（综合）