Knowledge of crop–weed interference effects on weed biology along with yield penalties can be used for the development of integrated weed management (IWM) tactics. Nevertheless, little is known about the beneficial effects of soybean [Glycine max (L.) Merr.] density, an important aspect of IWM, on late Palmer amaranth (Amaranthus palmeri S. Watson) establishment time. Two field experiments were conducted in 2014 and 2015 to investigate how various soybean densities and A. palmeri establishment timings in weeks after crop emergence (WAE) affect height, biomass, and seed production of the weed but also crop yield in drill-seeded soybean. Soybean density had a significant impact on dry weight and seed production of A. palmeri that established within the first 2 wk of crop emergence, but not for establishment timings of the weed 4 wk and later in relation to crop emergence. Differential performance of A. palmeri gender was observed, regarding greater biomass production of female than male plants under crop presence, and merits further investigation. Grain yield reductions were recorded at earlier A. palmeri establishment timings (i.e., 0 and 1 WAE) compared with 8 WAE establishment timing in 2014 and 2015. High soybean densities resulted in greater soybean yields compared with low soybean density, but no grain yield benefits were observed between medium and high soybean densities. Crop budget analysis revealed the benefits of moderate seeding rate (i.e., 250, 000 seeds ha−1) increases in comparison to lower (i.e., 125,000 seeds ha−1) or high (i.e., 400,000 seeds ha−1) on crop revenue, net income returns, and breakeven price. Earlier A. palmeri establishment timings (i.e., 0, 1, and 2 WAE) resulted in lower crop revenue and net income returns compared with later establishment timings of the weed.

中文翻译：

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大豆密度和苋菜 (Amaranthus palmeri) 建立时间：对杂草生物学、作物产量和经济回报的影响

作物-杂草干扰对杂草生物学的影响以及产量损失的知识可用于制定综合杂草管理 (IWM) 策略。然而，人们对大豆的有益作用知之甚少[最大甘氨酸(L.) Merr.] 密度，IWM 的一个重要方面，晚帕尔默苋菜 (苋菜S. Watson) 成立时间。2014 年和 2015 年进行了两次田间试验，以研究不同的大豆密度和A. 帕尔梅里作物出苗后数周内的建立时间 (WAE) 会影响杂草的高度、生物量和种子产量，还会影响播种大豆的作物产量。大豆密度对干重和种子产量有显着影响A. 帕尔梅里在作物出苗的前 2 周内建立，但不适用于杂草 4 周及以后与作物出苗有关的建立时间。差异化表现A. 帕尔梅里观察到性别，因为在作物存在下雌性植物的生物量大于雄性植物，值得进一步调查。早些时候记录了粮食减产A. 帕尔梅里与 2014 年和 2015 年的 8 个 WAE 建立时间相比，建立时间（即 0 和 1 WAE）。与低大豆密度相比，高大豆密度导致大豆产量更高，但在中等和高大豆密度之间没有观察到谷物产量效益。作物预算分析揭示了适度播种量（即 250, 000 粒种子公顷-1) 与较低的（即 125,000 公顷种子）相比有所增加-1) 或高（即 400,000 颗种子公顷-1) 对作物收入、净收入回报和盈亏平衡价格的影响。早些时候A. 帕尔梅里与较晚的杂草建立时间相比，建立时间（即 0、1 和 2 WAE）导致作物收入和净收入回报较低。