以来自不同杂种优势类群的F₂选系基础群体郑58×LH196(SS类群)和昌7-2×MBUB (NSS类群)为试验材料，在5个选系密度下，采用混合选择方法，分别获得选系群体C₁～C₄世代。2017年种植40个世代群体材料，评价选系群体产量遗传增益及主要农艺性状变化特征。结果表明，随着选系密度的增加，不同类群的玉米选系群体产量遗传增益均先增加后降低，郑58×LH196和昌7-2×MBUB分别在150 000株/hm²和120 000株/hm²选系密度下产量遗传增益最高。高密度循环育种过程中选系群体株型性状受选择影响较小，产量与生育期及穗部性状相关性较高。为进一步提高遗传增益，高密度循环育种应从C₁或更早世代开始加大密度选择压力，在后代材料中应注重早开花和行粒数的选择以及穗长和百粒重等性状的协同改良。

The F₂ selection base population Zheng 58×LH196(SS group) and Chang7-2×MBUB(NSS group) from different heterotic groups were selected as experimental materials. The mass selection was adopted to obtain C₁-C₄ generations under the five densities. In 2017, 40 generation populations obtained from the two groups under five different densities were planted to evaluate the genetic gain of yield and the change of main agronomic traits. The results showed that the genetic gain in grain yield for selected population groups first increased and then decreased as density increased. Zheng 58×LH196 and Chang 7-2×MBUB reached the highest genetic gain under the density of 150 000 and 120 000 plants/ha, respectively. In the process of high density cycle breeding, the plant type traits were less affected by selection, and the significant correlation between yield and growth and ear traits was found. In order to further improve genetic gain, maize cycle improvement should be carried out in a suitable high-density environment, and density selection pressure should be increased from C₁ or earlier generation. Additionally, emphasis should be placed on selecting for early flowering, row number, ear length, and 100-grain weight.

S513.031

国家重点研发计划项目(2022YFD1200802);国家玉米产业技术体系(CARS-02-02)