Abstract Seed number (SN) is positively associated with aboveground dry matter (ADM) accumulation in most crop species. In soybean, there are discrepancies among studies relative to the start and end of the critical period for seed number determination. The objective of this study was to more precisely identify those two stages. To do so, we followed two approaches: (i) analyses of experimental data where differences in SN occurred as a result of variation in crop growth due to weather and management practices and (ii) review of published experiments where soybean was subjected to artificial stresses during specific crop phases. Following the first approach, we analyzed the relationships between SN versus ADM accumulation and its components, crop growth rate (CGR) and duration, for different reproductive phases using data from experiments that portrayed a wide range of environments and management practices. In the second approach, we compared SN values in stressed versus non-stressed treatments. Accumulated ADM during the R3 to R6 phase explained ca. 70 % of the variation in SN across experiments. The CGR during R3-R6 was also a good predictor of SN, but it had lower explanatory power compared with accumulated ADM, because CGR did not account for changes in duration of critical period across experiments. Review of published data, wherein soybean crops were subjected to artificial stresses during different reproductive phases, confirmed that the R3-R6 phase is a critical phase for SN determination in soybean. Key findings of this study were: (i) critical period for SN determination in soybean occurs during the R3-R6 phase and (ii) accumulated ADM during the critical period is a better predictor of SN compared with CGR because it accounts for differences in the duration of the critical period as a result of weather and management.

中文翻译：

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由作物生长速率、持续时间和干物质积累决定的大豆种子数确定关键期

摘要 在大多数作物物种中，种子数 (SN) 与地上干物质 (ADM) 积累呈正相关。在大豆中，关于种子数确定关键期的开始和结束的研究之间存在差异。本研究的目的是更准确地确定这两个阶段。为此，我们采用了两种方法：(i) 分析由于天气和管理实践导致作物生长变化而导致 SN 差异的实验数据，以及 (ii) 审查已发表的大豆受到人工胁迫的实验在特定的作物阶段。按照第一种方法，我们分析了 SN 与 ADM 积累及其组成部分、作物生长率 (CGR) 和持续时间之间的关系，使用来自描绘各种环境和管理实践的实验数据来分析不同的繁殖阶段。在第二种方法中，我们比较了压力和非压力处理中的 SN 值。R3 到 R6 阶段期间累积的 ADM 解释了大约。70% 的实验中 SN 的变化。R3-R6 期间的 CGR 也是 SN 的一个很好的预测因子，但与累积的 ADM 相比，它的解释力较低，因为 CGR 没有考虑整个实验的关键期持续时间的变化。回顾已发表的数据，其中大豆作物在不同繁殖阶段受到人工胁迫，证实 R3-R6 阶段是大豆 SN 测定的关键阶段。这项研究的主要发现是：