Development of ideal breeding and crop management strategies that can improve maize grain yield under tropical environments is crucial. In the temperate regions, such yield improvements were achieved through use of genotypes that are adapted to high plant population density stress. However, tropical germplasm has poor tolerance to high plant population density stress, and thus it should be improved by introgressing temperate maize germplasm. The aim of this study was to estimate the genetic gains and identify traits associated with such gains in stable and high yielding temperate × tropical hybrids under low and high plant population densities. A total of 200 hybrids derived from a line × tester mating design of tropical × temperate germplasm were developed. These hybrids were evaluated for grain yield and allied traits under varied plant population densities. High yielding and stable hybrids, such as 15XH214, 15XH215 and 15XH121, were resistant to lodging and had higher number of leaves above the cob. The high genetic gains of 26% and desirable stress tolerance indices of these hybrids made them better performers over check hybrids under high plant population density. At high plant population density yield was correlated to stem lodging and number of leaves above the cob. Future gains in grain yield of these hybrids derived from temperate × tropical maize germplasm can be achieved by exploiting indirect selection for resistance to stem lodging and increased number of leaves above the cob under high plant density conditions.

开发能够在热带环境下提高玉米产量的理想育种和作物管理策略至关重要。在温带地区，这种产量提高是通过使用适应高植物种群密度胁迫的基因型实现的。然而，热带种质对高植物种群密度胁迫的耐受性较差，应通过引入温带玉米种质进行改良。本研究的目的是在低和高植物种群密度下估计稳定和高产温带×热带杂交种的遗传增益并确定与这种增益相关的性状。从热带×温带种质的品系×测试仪交配设计中，共开发出200个杂种。在不同的植物种群密度下评估这些杂种的谷物产量和相关性状。15XH214、15XH215 和 15XH121 等高产且稳定的杂种具有抗倒伏性，并且穗轴上方的叶子数量较多。这些杂种 26% 的高遗传增益和理想的胁迫耐受性指数使它们在高植物种群密度下表现优于对照杂种。在高植物种群密度下，产量与茎倒伏和穗轴上方的叶子数量相关。这些源自温带×热带玉米种质的杂交种的未来谷物产量增加可以通过在高植物密度条件下利用间接选择来抵抗茎倒伏和增加玉米棒上方的叶子数量来实现。15XH215 和 15XH121 抗倒伏，穗轴上方的叶子数量较多。这些杂种 26% 的高遗传增益和理想的胁迫耐受性指数使它们在高植物种群密度下表现优于对照杂种。在高植物种群密度下，产量与茎倒伏和穗轴上方的叶子数量相关。这些源自温带×热带玉米种质的杂交种的未来谷物产量增加可以通过在高植物密度条件下利用间接选择来抵抗茎倒伏和增加玉米棒上方的叶子数量来实现。15XH215 和 15XH121 抗倒伏，穗轴上方的叶子数量较多。这些杂种 26% 的高遗传增益和理想的胁迫耐受性指数使它们在高植物种群密度下表现优于对照杂种。在高植物种群密度下，产量与茎倒伏和穗轴上方的叶子数量相关。这些源自温带×热带玉米种质的杂交种的未来谷物产量增加可以通过在高植物密度条件下利用间接选择来抵抗茎倒伏和增加玉米棒上方的叶子数量来实现。这些杂种 26% 的高遗传增益和理想的胁迫耐受性指数使它们在高植物种群密度下表现优于对照杂种。在高植物种群密度下，产量与茎倒伏和穗轴上方的叶子数量相关。这些源自温带×热带玉米种质的杂交种的未来谷物产量增加可以通过在高植物密度条件下利用间接选择来抵抗茎倒伏和增加玉米棒上方的叶子数量来实现。这些杂种 26% 的高遗传增益和理想的胁迫耐受性指数使它们在高植物种群密度下表现优于对照杂种。在高植物种群密度下，产量与茎倒伏和穗轴上方的叶子数量相关。这些源自温带×热带玉米种质的杂交种的未来谷物产量增加可以通过在高植物密度条件下利用间接选择来抵抗茎倒伏和增加玉米棒上方的叶子数量来实现。