亚种间杂种优势利用的设想与实践

Since Prof. Yuan Longping put forward a suggestion on utilization of heterosis between subspecies in 1986, a great upsurge in development of subspecific hybrids by using two-line and three-line methods has been formed in China. However,when the two-line method is used , the fertility expression of the genie sterile line is greatly influenced by the environments, which results in increase of difficulties in use of wide compatibility materials. If the three-line method is used to make japonica/javonica and indica/javonica, the difficulty in use of wide compatibility materials may be overcome without a hitch. Our idea is to do this by 2 stages. In the first stage the secondary subspecific hybrids are developed by making japonica and javonica cross or indica and javonica cross, and in the second stage utilization of heterosis between subspecies is realized by developing hybrids between japonica and indica. In utilization of heterosis between secondary subspecies japonica and japonica a breeding pattern of ecological breeding+ideal plant type+heterosis has been formed. Based on the light and temperature conditions in the north, grain quality and concrete environments, several new hybrid combinations such as Tijin A/ C9022,Qiuguang A/C9022 and Xiuling A/C9002 have been developed by using the local short statured sterile lines of japonica type with good grain quality as female parents and the almost short statured wide compatibility restorer line of javonica type with large panicles as male parent. Their panicle number per mu may reach 280-300 thousand, and their spikelet number per mu 39. 20-42. 00 million, 20%-28% more than that of Xiu-You 57. If their seed setting percentage is 80%, their grain yield per mu may be 735-840kg. , At present, the "WA" sterile line of indica type is used to develop hybrids between indica and japonica. Their yield potential may reach 800-900kg per mu. However , they cannot be used in production yet due to their unstable seed setting percentage and unfilled grains Which are caused by the environments.