Relationships between Environmental Coditions and Production-and Consumption Activoties of Individual Leaves in the Population of Rice Plant in a Paddy Field : V. Leaf positional and seasonal changes of some oraganic and mineral components of the individual leaf in the population of different plant spacing and fertilization

[摘要] 1. Total sugar concentration in leaf blade decreased with time from meiosis stage to ripening stage, the maximum being 7% and the minimum 5.0-5.5% at the meiosis stage. Leaf positional differenccs of concentration were small (1.5-2.0%) during all the experimental period. Crude starch concentration increased until heading stage, but declined to a halh at the ripening stage. The leaves which showed maximum concentration were the 2nd or the 3rd leaf inl total sugar and the 1st or the 2nd leaf in crude starch. 2. Nitrogen concentration was the highest in the uppermost leaf during all the experimental period, and higher with the high level than with the low level of fertilization. The pattern of seasonal and leaf positional change of nitrogen content per unit leaf area was similar to that of concentration and the nitrogen content of each leaf changed parallel to the rates of photosynthesis and respiration. Concentration of potassium changed to a small extent, being 2.O-2.5% during all the experimental period, although that for upper leaves was somewhat higher. Content of potassium per leaf area decrcased as the leaf position descended and gradually decreased as the stage progresscd. In general, contents of carbohydrates, nitrogen and potassium were higher in plants with wide spacing than those with closc spacing, except meiosis stage. 3. Photosynthetic rates ran almost parallel with nitrogen content at each leaf, but showcd no relationship with the contents of other components, and the C/P ratios (ratios of the contents of each component to photosynthetic rate) excluding nitrogen became greater as the leaf position was lowered.

[学科分类] 农业科学（综合）