Crop-Scientific Studies on the Yield-Formation and the Yield-Forecast of Lowland Rice. : XXXIII. Carbon assimilation of rice plants under natural conditions.

Abstract

Using the same apparatus reported in the previous papers, the authors made further experiments. 1) The differences of the light curves of carbon assimilation in nursery beds between thinly and thickly spaced rice-seedlings could hardly be found. 2) Nitrogen supplies at different growing stages always increased the photosynthetic activity of rice plants. Especially, the top-dressing at the beginning stage of panicle differentiation caused the rice plants to make a marked increase in the rate of carbon assimilation per unit leaf-area. 3) Drought and shading treatments decreased the rate of carbon assimilation, but the assimilating rates of shaded plants were much more active than the normal ones at a certain period after finishing. the treatments. 4) Fertile tillers (which bear heads) were superior to sterile tillers (which fail to head) in the photosynthetic activity at the time shortly after the stage of maximum number of tillers. 5) Rice plants subjected to strong wind decreased their photosynthetic activity. 6) Carbon assimilation of rice plants in actual fields were measured also. The results were nearly the same as those of previous papers, except for the seasonal changes of carbon assimilation.