Most maize production across the globe is rain-fed, and production is set to be negatively impacted as duration and occurrence of droughts increases due to climate change. Development of water-deficit tolerant maize germplasm has been a major focus for most breeding programmes. Here, we sought to assess the genetic gain for grain yield in two maize populations developed for drought tolerance at CIMMYT by evaluating their cycle progeny through hybrid performance. Inbreds derived from different cycles of the Drought Tolerant Population (DTP) and La Posta Sequia (LPS) were mated to a tester (CML550), and resulting hybrids were evaluated under managed water-deficit stress and well-watered conditions. The difference in yield between water-deficit and well-watered treatments was 27% and 36% for the DTP and LPS, respectively. Genetic gain for grain yield across cycles for the two populations was confirmed in the study. Genetic gain was observed for both treatments indicating that selection for water-deficit stress tolerance simultaneously improves grain yield in well-watered conditions. The DTP population had a genetic gain of 0.07 t ha⁻¹ cycle⁻¹, while the LPS had 0.16 t ha⁻¹ cycle⁻¹ under water-deficit conditions. Significant genetic gain was also observed in the well-watered treatments for both populations. Anthesis to silking interval was significantly reduced under water-deficit stress conditions in both populations. Plant and ear height were reduced in the LPS population in both treatments, while no reductions were observed for the trait in the DTP population. Potential water-deficit stress tolerance donor lines with yields comparable to commercial check varieties were identified.

中文翻译：

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亚热带玉米种群耐旱性选择遗传增益的表型评估

全球大部分玉米生产都是靠雨养的，随着气候变化导致干旱的持续时间和发生率增加，产量将受到负面影响。开发耐缺水玉米种质一直是大多数育种计划的主要重点。在这里，我们试图通过杂交性能评估其周期后代来评估 CIMMYT 开发的两个耐旱玉米种群的谷物产量的遗传增益。将来自耐旱种群 (DTP) 和 La Posta Sequia (LPS) 的不同周期的近交系与测试仪 (CML550) 交配，并在受控缺水胁迫和水分充足的条件下对所得杂交种进行评估。对于 DTP 和 LPS，缺水和充分浇水处理之间的产量差异分别为 27% 和 36%。该研究证实了两个种群跨周期谷物产量的遗传增益。两种处理均观察到遗传增益，表明选择缺水胁迫耐受性同时提高了水分充足条件下的谷物产量。DTP 种群的遗传增益为 0.07 t ha^-1 cycle ^-1，而LPS在缺水条件下有0.16 t ha ^-1 cycle ^{-1 。}在两个种群的充分浇水处理中也观察到显着的遗传增益。在缺水胁迫条件下，两个种群的花期到吐丝间隔显着缩短。在两种处理中，LPS 种群的植物和穗高都降低了，而 DTP 种群的性状没有观察到降低。确定了产量与商业对照品种相当的潜在缺水胁迫耐受性供体系。