| Rice is an important food crop in the world;therefore,it is of great significance ensuring the safe production of rice.Rice blast and borer are the common pests and diseases that endanger the safety production of rice.According to the long-term practice,it has been found out that cultivating or discovering new varieties of disease and insect pests carrying resistance genes is the main method for preventing rice diseases and insect pests.In this research,based on the previous researches and the Bt transgenic rice obtained from the preliminary work of the laboratory,it adopts the molecular marker-assisted selection and backcross technology to transfer the three rice Pi-ta,Pib and Pikm carried in Chuankang 30 Blast resistance genes to Changhui 121 T,Changhui 891 T,and R205 XT insect-resistant rice restorer strain,after which it has obtained a batch of improved multi-gene strain that carries both borer and rice blast resistance genes.Later on,after comprehensive experiments such as resistance identification at seedling stage,inspection of agronomic traits,and analysis of combining ability,etc.,it evaluates the actual improvement effect of the polymer strains.Here are the main research results:(1)Through molecular marker-assisted selection breeding,and a total of 30 improved strains that carry resistance genes were obtained.Including 2 Changhui 121 T improved strains that carry Pi-ta homozygous genes;4 Changpi 891 T improved strains that carry Pib homozygous genes,4 carry Pikm homozygous genes,and 3 carry Pikm and Pib homozygous double genes Lines;6 R205 T improved strains that carry Pib homozygous genes,7 carry Pikm homozygous genes,2 carry Pib and Pikm homozygous double genes,and 2 carry Pi-ta,Pib and Pikm homozygous triple genes;(2)According to the genetic background analysis,except for the JH891-10 strain,it has been found out that the background recovery rate of the other improved strains that have been tested exceeded 93.75% of the theoretical value.While in the analysis of agronomic traits,except for the two strains of JH891-1 and JH891-10,whose 1000-grain weight was extremely and significantly or significantly reduced,and the ear length of the JH205-16 line was significantly reduced,while the remaining agronomic traits of the improved strains showing no significance differences(3)During the insect resistance identification experiment,the resistance level of the borer of the improved strain did not have any change with the introduction of the rice blast resistance gene.Through the laboratory spray inoculation experiment at seedling stage,the blast disease resistance level of rice of the improved strains was significantly improved compared to the original parents.Among which the disease resistance levels of the single and double gene homozygous strains were both disease resistant and the triple gene homozygous strains showed a high resistance of disease;(4)During the analysis of the cohesion analysis,only the JH205-14 strain surpassed the reincarnate parents in general cohesion.And among the 66 combinations,the one with the highest yield per plant is the Yexiang A/JH205-14.Shape and properties such as number of branch stems,total grains,real grains,seed setting rate,thousand-grain weight,etc.of the hybrid combination mainly depend on the parental function,while plant height,effective ear,panicle length,and yield per plant depend on the joint action of the parents. |
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