Understanding the effects of crop management practices on weed survival and seed production is imperative in improving long-term weed management strategies, especially for herbicide-resistant weed populations. Kochia [Bassia scoparia (L.) A.J. Scott] is an economically important weed in western North American cropping systems for many reasons, including prolific seed production and evolved resistance to numerous herbicide sites of action. Field studies were conducted in 2014 in a total of four field sites in Wyoming, Montana, and Nebraska to quantify the impact of different crop canopies and herbicide applications on B. scoparia density and seed production. Crops used in this study were spring wheat (Triticum aestivum L.), dry bean (Phaseolus vulgaris L.), sugar beet (Beta vulgaris L.), and corn (Zea mays L.). Herbicide treatments included either acetolactate synthase (ALS) inhibitors effective on non-resistant B. scoparia or a non–ALS inhibiting herbicide effective for both ALS-resistant and ALS-susceptible B. scoparia. Bassia scoparia density midseason was affected more by herbicide choice than by crop canopy, whereas B. scoparia seed production per plant was affected more by crop canopy compared with herbicide treatment. Our results suggest that crop canopy and herbicide treatments were both influential on B. scoparia seed production per unit area, which is likely a key indicator of long-term management success for this annual weed species. The lowest germinable seed production per unit area was observed in spring wheat treated with non–ALS inhibiting herbicides, and the greatest germinable seed production was observed in sugar beet treated with ALS-inhibiting herbicides. The combined effects of crop canopy and herbicide treatment can minimize B. scoparia establishment and seed production.

中文翻译：

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作物冠层和除草剂施用对地肤 (Bassia scoparia) 密度和种子产量的影响

了解作物管理实践对杂草生存和种子生产的影响对于改进长期杂草管理策略至关重要，特别是对于抗除草剂杂草种群。地肤 [地瓜(L.) AJ Scott] 是北美西部种植系统中经济上重要的杂草，原因有很多，包括多产的种子生产和对众多除草剂作用位点的抗性进化。2014 年在怀俄明州、蒙大拿州和内布拉斯加州的四个田间地点进行了实地研究，以量化不同作物冠层和除草剂应用对牛蒡密度和种子产量。本研究中使用的作物是春小麦（小麦L.), 干豆 (菜豆L.), 甜菜 (甜菜L.) 和玉米 (玉米L.)。除草剂处理包括对非抗药性有效的乙酰乳酸合酶 (ALS) 抑制剂牛蒡或对 ALS 抗性和 ALS 易感性均有效的非 ALS 抑制性除草剂牛蒡.地瓜除草剂选择对密度的影响比作物冠层的影响更大，而牛蒡与除草剂处理相比，作物冠层对每株种子产量的影响更大。我们的研究结果表明，作物冠层和除草剂处理都对牛蒡单位面积的种子产量，这可能是这种一年生杂草物种长期管理成功的关键指标。在用非 ALS 抑制性除草剂处理的春小麦中观察到每单位面积的可发芽种子产量最低，在用抑制 ALS 的除草剂处理的甜菜中观察到最大的可发芽种子产量。作物冠层和除草剂处理的综合影响可以最大限度地减少牛蒡建立和种子生产。