Reseaarch on Rice Breeding Through Crossing Indica and Japonica and Its Evolution in the Past Thirty Six Years
Yang Shou-jen et al Professor of Agronomy, Shenyang Agriculture University
This study began in 1951, and the paper "Advances in rice cross breed- ing between indica and japonica and its prospect" was issued in 1986. Thirty six years' work can be briefly summarized as follows: 1. The partial sterility and unordinary segregation of its offspring can be effectively overcome by multiple crossing, especially by using varie- ties other than parental ones, so as to broaden the genetic basis and enh- ance the efficiency of selection. 2. The conventional varieties bred by such inter-subspecies cross have performed brilliantly at home and abroad. Their yield potential may often be as high as that of the hybrid rice. Therefore, some of them are spread widely and enjoy great popularity among rice farmers in their adaptable regions, 3. It has been strengthened significantly by the theory of ideotype morphologically and physiologically. Besides, such varieties may have "non- F_1 vigour". All these may be the reason why they ussually have good productivity. 4. It is expected that various intermediate types between indica and japonica and super-high-yield rice varieties will appear in the years to come. 5. This approach to rice breeding has been studied for more than thirty years and proved by many rice breeders in various regions over the past two decades. It has many merits and distinct peculiarities of its own. Here we formally recommend that it be added to the contents of related teaching materials and books.