Evaluation On Rice Seedlings With Submergence Tolerance And Genome-Wide Association Study

Among the various rice production methods,the live broadcast technology has become an ideal way for light and efficient cultivation of rice in China due to its advantages of light weight,high efficiency,water saving,and labor saving.However,due to the direct seeding and seedling problems caused by direct water broadcasting,the main contributing factor is that the seeds of direct seeding rice are in a hypoxic stress environment under flooding conditions,which is not conducive to seedling emergence of direct seeding rice.Therefore,it is of great significance to excavate rice germplasm with good resistance to hypoxia germination.In this study,234 rice germplasms were used to measure the seed vigor phenotypes under normal conditions and hypoxic conditions,and the correlation between seed germination resistance to hypoxia was analyzed;the shallow water layer in the field was simulated for submergence seedlings and a batch of high was selected.Vigor and low-oxygen-resistant rice germplasm;Eight agronomically disparate materials were used to examine the agronomic traits of the whole growth period,and the agronomic traits and yield characteristics of direct-seeded rice were analyzed;Simplified genomic sequencing was used to fully characterize submerged seedling traits.Genomic association analysis,mining potential candidate genes.The main findings are as follows:1.The phenotypes of germination rate,germination potential,germination index,vigor index,shoot length,root length,fresh weight,and dry weight were measured under normal conditions using 234 germplasm materials,and the length of the bud sheath was measured under hypoxic conditions.Diameter,bud length,shoot length,root length,fresh weight,and dry weight phenotype,seedling rate,seedling length,root length,fresh weight,and dry weight measured by submergence seedlings,and the seedling quality index was calculated.Types of traits were screened out for a variety of germplasm materials with high vitality and low oxygen tolerance,such as "Big Grain Red Maple","DAYAKON","Dwarf Nantes" and "Inner 6 You 7028".2.The seed vigor phenotypes measured under normal laboratory conditions and hypoxic conditions were independent variables.The seedling emergence rate and seedling quality index of the field were used as the dependent variables.The correlation analysis and multivariate stepwise regression analysis were used to obtain the survival rate of the seedlings.The germination rate,germination index,and length of the coleoptile were extremely significantly correlated,and the regression equation of the seedling quality index was obtained,so as to realize the prediction of seedling seedlings in the field through laboratory indicators.3.A comparison of agronomic traits and yield characteristics of direct-seeded rice and transplanted rice with different densities revealed that the direct-seeded rice plant had higher height,more developed root systems,more nutritious growth,shallower root distribution,more tillers,and early tillering.Low tiller sites,low heading rate,small panicles,small panicle weight,few panicles per panicle,early earing,low dry matter accumulation,and low SPAD values.After correlation analysis,regression analysis and path analysis of the yield of direct-seeded rice and transplanted rice,it was found that the ear number and single-ear weight were the most important factors affecting the yield of direct-seeded rice,and the spike rate of direct-seeded rice was increased and the variety with large spikes was selected.It is the key to improving the production of direct seed rice.4.A genome-wide association analysis was performed on traits such as vigor index,length of coleoptile,and dry weight of flood-resistant seedlings,which were closely related to flood-tolerant seedlings.A total of 37 sites with significant associations were identified,and 8 related to the vigor index were screened.Candidate genes,8 candidate genes related to the length of the coleoptile,and 9 candidate genes related to the dry weight of the flood-resistant seedlings.In summary,a series of rice germplasm resources with high vitality and low oxygen tolerance were screened in this study,and candidate genes related to the seedling-seeding traits of direct-seeded rice were excavated,providing a certain theoretical and material basis for the study of direct-seeded rice.