提高种植密度是玉米增产的关键措施之一,种质改良是培育优良耐密种质的基础。课题组前期以陕B群选育的玉米自交系KB182和国内骨干自交系昌7-2为基础材料,通过多年不同轮次的改良培育了KB204、KB588等6个新自交系。为了探究不同轮次的改良效应,本研究以KB182、昌7-2及其不同轮次的改良系为材料,通过不同密度(60,000、90,000和120,000株/hm2)试验,评估了不同轮次改良系的耐密性、产量；并结合Maize 6H60K SNP分子标记,对改良后的自交系进行了遗传背景分析。结果表明,改良后的自交系产量较KB182和昌7-2有所提高,且随着密度的增加,自交系产量逐步提高；改良系的耐密系数较两个基础材料也有一定的提高；穗位叶叶夹角、茎秆强度、穗位系数、ASI(吐丝散粉间隔期)等主要耐密性状优于KB182和昌7-2。基于6H60K SNP基因型数据发现,随着不同轮次的改良,各个自交系保留的KB182遗传背景逐渐提高,昌7-2遗传背景逐渐降低,并保持在一定水平。同时,不同轮次自交系中基因型一致的纯合SNP位点有9,139个,占有效标记的25.13%。综上所述,基于KB182和昌7-2改良的不同轮次玉米自交系保留了基础材料的耐密特性,并在产量上得到了有效改良。

Increasing planting density is one of the key measures to increase maize yield, and germplasm improvement is the basis for cultivating excellent density-tolerant germplasm. In the early stage, the research group used the maize inbred line KB182 selected by Shaan B group and the domestic backbone inbred line Chang7-2 as the basic material, and cultivated six new inbred lines such as KB204 and KB588 through different rounds of improvement for many years. In order to explore the improvement effect of different rounds, this study used KB182, Chang7-2 and their different rounds of improved lines as materials, and evaluated the density tolerance and yield of different rounds of improved lines through different densities ( 60,000,90,000 and 120,000 plants/hm2). Combined with Maize 6H60K SNP molecular markers, the genetic background of the improved inbred lines was analyzed.The results showed that the yield of improved inbred lines was higher than that of KB182 and Chang7-2, and the yield of inbred lines increased gradually with the increase of density. The density tolerance coefficient of the improved line was also higher than that of the two basic materials. The main density tolerance traits such as ear leaf angle, stem strength, ear position coefficient, and ASI ( silking interval ) were better than KB182 and Chang 7-2. Based on the 6H60K SNP genotype data, it was found that with the improvement of different rounds, the genetic background of KB182 retained by each inbred line gradually increased, and the genetic background of Chang7-2 gradually decreased and remained at a certain level. At the same time, there were 9,139 homozygous SNP loci with the same genotype in different rounds of inbred lines, accounting for 25.13% of the effective markers. In summary, the different rounds of maize inbred lines improved based on KB182 and Chang7-2 retained the density tolerance characteristics of the basic materials and were effectively improved in yield.

陕西省科技厅项目(2024ZY-CGZY-17)和现代农业产业技术体系专项(玉米)(CARS-02-77)