Reasons and Countermeasures of Slow Development on Three-line Japonica Hybrid Rice

At present,the planting area of japonica hybrid rice accounts for only 3% of japonica area in China.Compared with the development of indica hybrid rice,japonica hybrid rice develops slowly because of the difference in photoperiod-sensitivity and adaptability between indica and japonica,the difference in male sterility stability and flowering habits between BT type japonica CMS lines and WA type indica CMS lines as well as the rapid development of conventional japonica rice breeding.Therefore,in order to promote the development of japonica hybrid rice,some countermeasures were suggested as follows:increasing the fund input and human resources for japonica hybrid rice breeding,improving the grain quality and yield of restorer lines,utilizing more types of sterile cytoplasm resources,improving the flowering habits of japonica CMS lines,ensuring the seed purity of CMS lines in its multiplication and combining modern biotechnologies with conventional breeding methods.