Abstract
Studies were made to examine the yield response of different varieties of low-land rice plant to the direct supply of fertilizers to the rhizosphere of the growing plants and analyzed the results with special reference to the components of yield. Fertilizers with 13-13-13 analysis was applied to the depth of 12cm, 32-35 days before the heading date of each variety. The resultsof two seasons' studies are summarized as follows. 1. The average yield of all the varieties examined increased by about 13% with the treatment. At the same time, the number of panicles, the number of spikelets per plant, and the 1000 grains weight also increased but the percentage of ripened grains decreased. 2. The yield of a given variety under the condition of the treatment was mainly determined by the rate of increase of yield in response to the treatment irrespective of the yield under the standard condition and the tendency of the variety whose ripeness of grains not to be lowered by heavy fertilization. 3. The varieties of heavy panicle type tended to produce a good crop responding favorably to the treatment. 4. High significant correlation was not found of the yield of the varieties between the standard plots and the treated plots. This seems to be due to the lack of correlation between the percentages of ripened grains in both groups of plot.
