Soybean [Glycine max (L.) Merr.] has recently become a popular rotational crop in the Canadian Northern Great Plains where herbicide-resistant (HR) soybean cultivars have been widely adopted. Intense reliance on herbicides has contributed to the development of HR weeds in soybean and other crops. Cultural weed management practices reduce the need for herbicides and lower the selection pressure for HR weed biotypes by improving the competitiveness of the crop. The effects of two row spacings, three target densities, and three cultivars on the critical weed-free period (CWFP) in soybean were evaluated as three separate experiments in southern Manitoba. In the row-spacing experiment, soybean grown in narrow rows shortened the CWFP by up to three soybean developmental stages at site-years with increased weed pressure. In the target density experiment, low-density soybean stands lengthened the CWFP by one soybean developmental stage compared with higher-density soybean stands. The effect of soybean cultivar varied among locations, yet tended to be consistent within location over the 2-yr study, suggesting that competitive ability in these soybean cultivars was linked to edaphic and/or environmental factors. Generally, the cultivar with the shortest days to maturity, which also had the shortest stature, consistently had a longer CWFP. Each of these cultural practices were effective at reducing the need for in-crop herbicide applications.

中文翻译：

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文化杂草管理实践缩短了在大平原北部种植的大豆的关键无杂草期

大豆 [最大甘氨酸(L.) Merr.] 最近在加拿大北部大平原成为一种流行的轮作作物，抗除草剂 (HR) 大豆品种已被广泛采用。对除草剂的强烈依赖促进了大豆和其他作物中 HR 杂草的发展。文化杂草管理实践通过提高作物的竞争力来减少对除草剂的需求并降低对 HR 杂草生物型的选择压力。在曼尼托巴省南部作为三个独立的实验评估了两个行距、三个目标密度和三个栽培品种对大豆关键无杂草期 (CWFP) 的影响。在行距实验中，在杂草压力增加的情况下，窄行种植的大豆在每个地点年将 CWFP 缩短了多达三个大豆发育阶段。在目标密度实验中，与高密度大豆林分相比，低密度大豆林分将 CWFP 延长了一个大豆发育阶段。大豆品种的影响因地区而异，但在为期 2 年的研究中往往在地区内保持一致，这表明这些大豆品种的竞争能力与土壤和/或环境因素有关。一般来说，成熟天数最短的品种，也有最短的身材，始终具有较长的CWFP。这些文化实践中的每一种都有效地减少了对作物除草剂应用的需求。表明这些大豆品种的竞争能力与土壤和/或环境因素有关。一般来说，成熟天数最短的品种，也有最短的身材，始终具有较长的CWFP。这些文化实践中的每一种都有效地减少了对作物除草剂应用的需求。表明这些大豆品种的竞争能力与土壤和/或环境因素有关。一般来说，成熟天数最短的品种，也有最短的身材，始终具有较长的CWFP。这些文化实践中的每一种都有效地减少了对作物除草剂应用的需求。