Current status and prospects of Japonica hybrid rice breeding in Jiangsu, China.

Research on Japonica hybrid rice in Jiangsu Province began in the end of 1970s.From 1982 and 1983,cooperation researches on Japonica hybrid rice breeding in Eastern China and in South China were organized respectively.Some Japonica hybrid combinations such as Yanyou 57V,Xuyou 3-2,Liuyou 1,Liuyou 3-2 were firstly developed.However,because of the non-integrity of seed production system,these hybrids were not so popularized as they were.After 1996,breeding for japonica hybrids made a great breakthrough in both middle season and late season hybrids.The successful development of the middle season hybrids broken the wandering phase for years in japonica hybrid rice breeding.Grain quality was greatly improved in late season hybrids.And great progress was made in seed multiplication and seed production.However,problems such as not pronounced heterosis in grain yield,poor resistance to stripe virus disease,un-stabile of sterility for BT type CMS lines,poor purity of hybrid seeds,lower yield performance and higher cost in seed production,lacking of technological cultivation system still existed in Japonica hybrid rice breeding.In order to speed up the Japonica hybrid rice breeding in Jiangsu Province,more attention should be paid to the development of R lines with strong restoring ability and CMS lines with high outcross ability,breeding for new hybrids in middle season with late maturity and research on seed production technology for higher yield and lower cost.