Abstract
The effect of a short root characteristic of rice plant on yield was investigated by comparing the yield and yield components of cultivar Oochikara with those of IL-srt1, a short root near isogenic line derived from Oochikara. The percentage of the yield in IL-srt1 (507g/m2) to that in Oochikara (745g/m2) was 68%. The percentage of ear number, number of grains per head, percentage of ripened grains and 1000 grain weight in IL-srt1 were 91%, 100%, 80%, 95% of those in Oochikara, respectively. Low yield ability of IL-srt1 was mainly attributed to a low percentage of ripened grains. The percentage of fertilized grains and that of fully ripened grains, which are components of the percentage of ripened grains in IL-srt1 were 74% and 108% of those in Oochikara, respectively. Although the percentage of fertilized grains in IL-srt1 was lower than that in Oochikara, the percentage of fully ripened grains to fertilized grains in IL-srt1 was higher than that in Oochikara. These results imply that the low yield ability of IL-srt1 is attributed to the effect of the short-root gene of IL-srt1, which reduces the percentage of ripened grains by decreasing the percentage of fertilized grains.
