A marker-assisted recurrent selection (MARS) program was undertaken in sub-Saharan Africa to improve grain yield under drought-stress in 10 biparental tropical maize populations. The objectives of the present study were to evaluate the performance of C1S2-derived hybrids obtained after three MARS cycles (one cycle of recombination (C1), followed by two generations of selfing (S2), and to study yield stability under both drought-stress (DS) and well-watered (WW) conditions. For each of the 10 populations, we evaluated hybrids developed by crossing 47–74 C1S2 lines advanced through MARS, the best five S5 lines developed through pedigree selection, and the founder parents with a single-cross tester from a complementary heterotic group. The hybrids and five commercial checks were evaluated in Kenya under 1–3 DS and 3–5 WW conditions with two replications. Combined across DS locations, the top 10 C1S2-derived hybrids from each of the 10 biparental populations produced 0.5–46.3 and 11.1–55.1 % higher mean grain yields than hybrids developed using pedigree selection and the commercial checks, respectively. Across WW locations, the best 10 hybrids derived from C1S2 of each population produced 3.4–13.3 and 7.9–36.5 % higher grain yields than hybrids derived using conventional pedigree breeding and the commercial checks, respectively. Mean days to anthesis of the best 10 C1S2 hybrids were comparable to those of hybrids developed using the pedigree method, the founder parents and the commercial checks, with a maximum difference of 3.5 days among the different groups. However, plant height was significantly (P < 0.01) different in most pairwise comparisons. Our results showed the superiority of MARS over pedigree selection for improving diverse tropical maize populations as sources of improved lines for stress-prone environments and thus MARS can be effectively integrated into mainstream maize breeding programs.

中文翻译：

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使用标记辅助轮回选择和谱系选择程序开发的玉米种群的性能和谷物产量稳定性

在撒哈拉以南非洲开展了一项标记辅助轮回选择 (MARS) 计划，以提高 10 个双亲热带玉米种群在干旱胁迫下的谷物产量。本研究的目的是评估在三个 MARS 循环（一个重组循环 (C1)，然后是两代自交 (S2)）后获得的 C1S2 衍生杂种的性能，并研究两种干旱胁迫下的产量稳定性(DS) 和良好浇水 (WW) 条件。对于 10 个种群中的每一个，我们评估了通过杂交 47-74 个通过 MARS 推进的 C1S2 品系开发的杂种，通过系谱选择开发的最佳 5 个 S5 品系，以及具有来自互补杂种优势群体的单交叉测试者。在肯尼亚，在 1-3 DS 和 3-5 WW 条件下对杂交种和五项商业检查进行了评估，两次重复。跨 DS 位置组合，来自 10 个双亲群体中的每一个的前 10 个 C1S2 衍生杂种产生的平均谷物产量分别比使用谱系选择和商业检查开发的杂种高 0.5-46.3% 和 11.1-55.1%。在整个 WW 地点，来自每个种群的 C1S2 的最佳 10 个杂交种的谷物产量分别比使用传统谱系育种和商业检查衍生的杂交种高 3.4-13.3% 和 7.9-36.5%。最好的 10 个 C1S2 杂种的平均开花天数与使用谱系方法、创始人亲本和商业检查开发的杂种相当，不同组之间的最大差异为 3.5 天。然而，在大多数成对比较中，株高有显着差异（P < 0.01）。我们的结果表明，MARS 优于系谱选择，可作为易受胁迫环境的改良品系来源，在改良不同热带玉米种群方面具有优势，因此 MARS 可以有效地整合到主流玉米育种计划中。