Analysis of Yield-Determining Process and Its Application to Yield Prediction and Culture Improvement of Lowland Rice. : LXI. Studies on the nitrogen top-dressing at full heading time.

Abstract

Since the authors reported the favourable effects of the nitrogen top-dressing at full heading time on the rice plant in the previous paper (XL VII, Vol. 27, No. 1), they have further been examining them for those several years under the various conditions differing in the amount of basic fertilizer, time of planting, spacing and variety, and obtained the following conclusions. 1. Nitrogen top-dressing at full heading time caused the plant to increase the rate of photosynthesis and amount of dry-matter as well in the period after heading except the cases of extremly unfavourable weather conditions and extremely dense spacing. 2. When the amount of dry-matter was increased by nitrogen top-dressing at full heading time, it was generally observed that yield as well as the percentage of ripened grains were clearly increased independently of the time of planting, spacing and variety, except the case of the control (non-top-dressed) plot being high enough in its percentage of ripened grains. 3. No effect of nitrogen top-dressing at full heading time was found on the plant in the case of the translocation of carbohydrates being disturbed by cool temperature in autumn or the enough amount of nitrogen being supplied to the plant from the soil even in the period after heading.