Analysis of Developmental Factors Determining Yield and Its Application to Yield Prediction and Culture Improvement in Lowland Rice. : XLVII. Studied on the mechanism of ripening (8). : Relation of temperature to the rate of translocation of carbohydrates from leaves and culms to grains, and a method for increasing the percentage of ripened grains.

[摘要] 1) Two further experiments have been carried out to confirm the hypothesis, derived from the previous experiments (XLI, Vol. XXVI. No. 1.), that the gradient of sugar concentration in a rice plant is one of the most influential factors in determining the rate of translocation. From the experiments following facts have newly been made clear, as can be seen in Table 1: (1) the rate of translocation is markedly disturbed even in a midday by shading the rice plants, and (2) sugar concentration in a rice plant gradients in the order of leaf-blade>sheath>culm>panicle, and the gradient between a leaf-blade and a panicle is the larger at the time when the translocation is the more active. 2) Entire plants being subjected to different temperatures for 20 days after heading, the relation of the rate of translocation to the temperature has also been experimented. From the experiment it has been elucidated that the rate of translocation increases with the temperature up to about 25°C, but it seems to keep almost constant in higher temperatures than 25°C, as can be seen in Fig. 1 and 2. 3) Enabling the rice plant to favour its photosynthetic activity, the nitrogenous top-dressing at the time just after heading has been proved to play an important roll in increasing the percentage of ripened grains on many cases where rice plants have less contents than 1.25% in total nitrogen at heading time, as seen in Table 2.

[学科分类] 农业科学（综合）