Germplasm Evaluation For Production Of Ratooning And Direct-seeding Rice And Genetic Analysis Of Related Traits

With the development of aging and urbanization,the area of available cultivated land and agricultural labor force are decreasing.The traditional rice production model is no longer suitable for the requirements of China’s agricultural development.Light Simplified Cultivation Technology of rice is a new technology to improve production efficiency by reducing the investment of human and material resources.At present,direct seeding rice and ratooning rice are commonly used.However,there is still a shortage of rice varieties suitable for this planting mode.Therefore,it is of great significance to evaluate and screen rice germplasm suitable for the production of Ratooning Rice and direct seeding rice,and carry out genetic analysis on the regeneration ability of Ratooning Rice and the lodging resistance and hypoxia tolerance seedling emergence rate of direct seeding rice.In this study,the sequenced core germplasm accessions collected were verified by genotyping,and then purified.Then,the genotype data was obtained from Rice Var Map.At the same time,the modern breeding materials in our laboratory were sequenced by next-generation sequencing to obtain genotype data.The above germplasm resources were tested for three traits,including ratooing ablility,breaking resistance,and anaerobic germination tolerance to obtain phenotypic data.On the one hand,the germplasm resources suitable for the production of direct seeding rice and ratooning rice can be selected.On the other hand,the genes related to the above three traits can be located through genome-wide association analysis,and their genetic mechanism was preliminarily analyzed,so as to provide gene resources for the genetics and breeding of ratooning rice and direct seeding rice in the future.The main results are as follows:1.The ratooning ability of 160 accessions was evaluated.154 accessions had higher ratooning ability than the control Tianliangyou 616,147 accessions had less annual growth period than the control,15 accessions had higher annual yield than the control,and 80 accessions had higher yield than the control in ratooning season.The correlation coefficient between ratooning ability and yield in ratooning season is 0.73.2.In 311 accessions,the breaking resistances the third(N3)and forth(N4)internodes from the top were tested.One hundred and one accessions showed higher breaking resistance than the control Huanghuazhan,and the correlation coefficient between the tillering number per plant and breaking resistances of N3 and N4 were-0.710 and-0.650,respectively.The anaerobic germination tolerance of 308 accessions were evaluated.One hundred and thirty accessions showed higher anaerobic germination tolerance than the control Kho Hlan on.3.A total of 12 QTLs loci related to breaking resistance were located on chromosomes 2,3,4,6 and 8,by use of genome-wide association analysis of breaking resistance of N3 and N4.Two QTLs adjacent to the cloned gene region were found,and 10 new QTL were identified.Among them,q D3BR2-8 controling the breaking resistance of N3,and q D4BR1-8 controling the N4,were simultaneously detected in two environments.4.A total of 8 QTL related to anaerobic germination tolerance were located on chromosomes 2,3,5,6,7,and 12 in three different environments.Among them,four QTL were found adjacent or overlapped with the reported QTL / gene,and 4 QTL were newly identified in this study.