Genetic Variation Of Root System In Maize Breeding Population And Response Of Some Inbred Lines To Low Phosphorus Stress

Root is the main organ of maize to absorb nutrients and moisture, this experiment uses a maize breeding population consist of 500 inbred lines, to explore the natural variation of maize seedling root traits, by using high-throughput cultivation systemand root phenotype measurement platform. At the same time, compare the differences between the subpopulations, different germplasms and China’s 4 kinds of main breeding populations. Provide the reliable genetic material for the improvement of maize root by screening the outstanding inbred lines in root traits. What’s more, this paper uses Mainstay Inbred Line in China, Zheng 58 and the inbred lines in the genetic improvement progress of it (U8112, Shen 5003, Ye478, Dan340, Zheng58), to analysis the P use effifciency and root change trend of them. Results show:1. The root of this maize breeding population has abundant genetic variation in the seedling stage, and Screening special maize germplasm by root phenotype through cluster analysis, these excellent germplasm can be used for genetic improvement of maize root; under field condition, the root length of tropical germplasm TST subsets (mainly come from CIMMYT) is longer significantly in seedling stage,14%-24% higher than other subpopulations, but diameter is smaller than others, while the root length, root biomass and shoot biomass of the germplasm from USA are smaller than the germplasm from other countries.2. The high-throughput imaging system in this experiment has higher efficiency and accuracy; greenhouse high-throughput cultivation system, using the Turface medium, improves efficiency at the same time, the cultivation system reduces the environmental impact and sampling error, but in this experiment, there are differences between field condition and greenhouse condition that different subpopulations, different regions have different phenotypes in these two condition, therefore we need to evaluate the system in the further.3. The study of 5 inbred lines showed that Shen 5003 has deep root system; and there are genetic differences between the reactions of 5 lines in P stress condition, the root of Zheng58 and Shen5003 are more sensitive to P stress:in P0 and P1 treatments, Zheng58 and Shen5003 sinificantly increase the deep root lenght in 20-40cm soil depth, and the grain yield of them reduce less than other lines in P1 condition, that means Zheng58 inheritances the P efficiency of Shen5003; correlation analysis showed that the shoot biomass and root length of 20-40cm is positively correlated with the yield under different phosphorus levels.In summary, this study initially revealed the root genetic variation of maize breeding population, provide the reliable genetic materials for the genetic improvement of maize root, and reasonable evaluation of high-throughput cultivation system and root phenotype measurement platform, and further elucidate the root and P efficiency change trend by the genetic improvement process of Zheng 58, providing theoretical support for the root genetic improvement and P efficiency study.