Low soil nitrogen (low-N) and stem borer attack are two of the major stresses limiting maize production in West and Central Africa (WCA). Thus, there is need to intensify efforts aimed at identifying inbred lines with resistance and tolerance to these stresses for hybrid development. The objectives of the study were to determine the combining ability of maize inbred lines, classify them into heterotic groups using both conventional and marker-based approaches, compare the efficiency of the different grouping methods and evaluate the performance of the hybrids generated from the inbred lines under contrasting environments. Ten white maize inbred lines with varying levels of resistance to stem borers were selected and crossed in a diallel in 2015. The resulting 45 hybrids were evaluated together with five checks in 10 environments under low-N, artificial stem borer infestation and non-stress conditions in Nigeria. General combining ability (GCA) and specific combining ability (SCA) were highly significant ( p ≤ 0.01) for most of the traits studied but GCA was predominant over SCA under each and across research conditions. Inbred line 2 combined significant positive GCA for grain yield with significant negative GCA for traits of resistance to stem borers and tolerance to low-N. Each of the grouping methods classified the inbred lines into 3 heterotic groups but SCA and heterotic groups’ specific and general combining ability had the joint highest breeding efficiency. Hybrids 1 × 4, 2 × 3, 1 × 6 and 2 × 5 were identified to be high yielding and stable across environments and can serve as candidates for further on-farm evaluations and eventual release in WCA.

中文翻译：

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西非和中非热带玉米自交系杂种分组及其在螟虫侵染和低土壤氮条件下的杂交性能

土壤低氮（低氮）和螟虫侵袭是限制西非和中非 (WCA) 玉米生产的两个主要压力。因此，需要加紧努力，旨在确定对这些压力具有抗性和耐受性的近交系，以进行杂交发育。该研究的目的是确定玉米自交系的配合能力，使用传统和基于标记的方法将它们分类为杂种优势组，比较不同分组方法的效率并评估由自交系产生的杂种的性能在对比鲜明的环境下。2015 年选择了 10 个对螟虫具有不同抗性水平的白玉米自交系，并在双列中杂交。 在低氮条件下，在 10 个环境中评估了 45 个杂种，并进行了五次检查，尼日利亚的人工螟虫侵扰和非胁迫条件。对于大多数研究的性状，一般配合力（GCA）和特定配合力（SCA）非常显着（p≤0.01），但在每种研究条件下，GCA均优于SCA。自交系 2 将谷物产量的显着正 GCA 与对蛀虫抗性和低氮耐受性状的显着负 GCA 结合起来。每种分组方法将自交系分为3个杂种优势群，但SCA和杂种优势群的特异和一般配合力联合育种效率最高。杂交种 1 × 4、2 × 3、1 × 6 和 2 × 5 被确定为高产且跨环境稳定，可作为进一步农场评估和最终在 WCA 发布的候选者。