| Rice is one of the most important food crops in the world. Diseases and insect pests have greatly affected the yield and quality of rice. Rice blast is the most serious fungal disease of rice. The long-term practice has proved that modifying rice resistance assisted with resistant genes is the most effective methods for protecting diseases and insect pests. In this study, 29 restorer lines and six photo-thermo-sensitive genic male sterile lines developed in past years in our lab were used as male and female parents for cross testing to screen new two-line hybrids with blast resistance, high yielding and rice quality. Other work was that Hua15 bearing Bph14 and Bph15 genes was crossed with P9311 harboing Pi9 and XJ12202-9harboing Pi2, respectively, for selecting new restorer lines with multi-resistance genes.The following are the main results:1. The results of blast evaluation of 29 restorer lines showed that their leaf blast scores were 1-4, neck blast scores were 0-5, loss rate of neck blast were 0-1,composite index of resistance were 0.0-3.5. Of 29 restorer lines, three lines were highly resistant agains blast, 22 lines resistant against blast and four moderate resistant against blast, respectively.2. The results of blast evaluation of 130 crosses indicate that seven crosses are highly resistant against blast, 39 crosses are resistant against blast, 47 crosses are moderate against blast, 27 crosses are moderate susceptible to blast and 10 crosses are susceptible to blast, respectively. Comparesed with traditional breeding, the blast resistance of new crosses from new restorer lines is improved significantly.3. Three new combinations, Feng39S/YAQ1027ã€Hua1228S/YAQ10242 and Hua1228S/YAQ10272 were screen out among 130 testing crosses. The yields of Feng39S/YAQ1027, Hua1228S/YAQ10242 and Hua1228S/YAQ10272 are6.62%, 8.40% and 17.88% higher than that of the control, Feng liangyou 1,respectively. All of they are resistant against blast and show high quality.These combinations should be used and evaluated for their application in production in multi-point testing.4. 1500 plants from F2 segrage populations of Hua15/P9311 and Hua15 /XJ12202-9 are detected by MAS. The plants of F3 and F4 family lines are dected later. Finally, 17 restorer breeding lines carrying Bph15 and Pi9 genes and 26 lines carrying Bph14, Bph15 and Pi2 genes are selected through MAS and phenotype in the field.Further resistance identification and cross screening should be studied on these selected lines... |
