ABSTRACT Low-branching soybean cultivars have few nodes per plant, and there have been many cases in northern Japan where growing these cultivars at high plant densities did not improve yield. Soybean cultivar ‘Tokei 1122ʹ (T22), which has a long terminal raceme, was bred to improve the yield of low-branching cultivars under dense planting conditions. To elucidate the effects of long racemes on the suitability of T22 for dense planting, we compared the yield and yield components of T22 and ‘Toyoharuka’ (TH), which is a low-branching cultivar, at various planting densities. There was no significant difference in the seed yield of these cultivars at low planting densities, whereas the seed yield of T22 was significantly greater than that of TH under dense planting conditions. The increase in the number of seeds per unit area was greater for T22 than for TH. An analysis of variance revealed a significant interaction between cultivar and planting density for seed yield, number of pods, and number of pods per node. Moreover, the low-branching cultivar ‘Tokei 1122ʹ with long terminal racemes produced a higher yield under non-lodging conditions than the conventional low-branching cultivar at planting densities of 33 plants m−2 or higher. The greater yield of T22 is likely because of its long terminal raceme, which increases the number of pods per node and the sink capacity (number of seeds) at high planting densities. Graphical Abstract

中文翻译：

---

高种植密度条件下长末端总状花序 QTL 的大豆育种系 'Tokei 1122' 的产量及相关性状

摘要 低分枝大豆品种每株的节数很少，在日本北部有很多案例，以高密度种植这些品种并没有提高产量。大豆品种 'Tokei 1122ʹ (T22) 具有长末端总状花序，是为了在密集种植条件下提高低分枝品种的产量而培育的。为了阐明长总状花序对 T22 适用于密集种植的影响，我们比较了 T22 和 'Toyoharuka' (TH)（一种低分枝品种）在不同种植密度下的产量和产量构成。这些品种在低种植密度下的种子产量没有显着差异，而在密集种植条件下，T22的种子产量显着高于TH。T22 的单位面积种子数增加大于 TH。方差分析揭示了品种和种植密度之间在种子产量、豆荚数和每个节点豆荚数方面的显着交互作用。此外，在种植密度为 33 株 m−2 或更高时，具有长末端总状花序的低分枝品种 'Tokei 1122ʹ 在非倒伏条件下比常规低分枝品种产生更高的产量。T22 更高的产量可能是因为它的末端总状花序长，这增加了每个节点的豆荚数量和高种植密度下的汇容量（种子数量）。图形概要 在种植密度为 33 株 m−2 或更高时，具有长末端总状花序的低分枝品种 'Tokei 1122ʹ 在非倒伏条件下比常规低分枝品种产生更高的产量。T22 更高的产量可能是因为它的末端总状花序长，这增加了每个节点的豆荚数量和高种植密度下的汇容量（种子数量）。图形概要 在种植密度为 33 株 m−2 或更高时，具有长末端总状花序的低分枝品种 'Tokei 1122ʹ 在非倒伏条件下比常规低分枝品种产生更高的产量。T22 更高的产量可能是因为它的末端总状花序长，这增加了每个节点的豆荚数量和高种植密度下的汇容量（种子数量）。图形概要