Harvest weed seed control (HWSC) may control problematic weeds by decreasing contributions to the weed seedbank. However, HWSC practices will not be effective if plants have shed a great part of their seeds before harvest or if a low proportion of seed production is retained at a height that enables collection during harvest. The seed-shattering pattern of several weed species was evaluated over three growing seasons to determine their potential to be controlled with HWSC in the Pacific Northwest (PNW). The studied weed species were downy brome (Bromus tectorum L.), feral rye (Secale cereale L.), Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot], and rattail fescue [Vulpia myuros (L.) C.C. Gmel.]. Seed retention at harvest, seed production, and plant height differed among species, locations, and years. Environmental conditions influenced seed-shattering patterns, particularly the time plants started to shatter seeds and the rate of the shattering. Agronomic factors such as herbicide use, interrow space, or crop height/vigor also seemed to affect shattering patterns and seed production, but more specific studies must be conducted to determine their individual effects. Bromus tectorum, L. perenne ssp. multiflorum, and V. myuros had an average seed retention at harvest of less than 50%. In addition, the low seed retention height of V. myuros makes this species a poor candidate for HWSC. Secale cereale had average seed retention at harvest greater than 50%, and seed retention height was greater than 30 cm. The variability of seed retention in different species will make the efficacy of HWSC practices species and environment dependent in PNW winter wheat (Triticum aestivum L.) cropping systems. Harvesting the wheat crop as early as possible will be crucial to the success of HWSC.

中文翻译：

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太平洋西北部小麦收获时禾本科杂草的种子保留

收获杂草种子控制 (HWSC) 可以通过减少对杂草种子库的贡献来控制有问题的杂草。但是，如果植物在收获前已经脱落了大部分种子，或者如果在收获期间能够收集的高度保持低比例的种子产量，则 HWSC 做法将无效。在三个生长季节评估了几种杂草的种子破碎模式，以确定它们在太平洋西北部 (PNW) 受 HWSC 控制的潜力。研究的杂草种类是绒毛雀（无芒雀麦L.), 野黑麦 (黑麦L.)、意大利黑麦草 [黑麦草L. ssp。何首乌(Lam.) Husnot] 和鼠尾草 [狐猴(L.) CC Gmel.]。收获时的种子保留、种子产量和株高因物种、地点和年份而异。环境条件影响种子破碎模式，特别是植物开始破碎种子的时间和破碎速度。除草剂使用、行间间距或作物高度/活力等农艺因素似乎也影响破碎模式和种子产量，但必须进行更具体的研究以确定它们的个体影响。无芒雀麦,L. perennessp。何首乌， 和V. myuros收获时的平均种子保留率低于 50%。此外，低种子保留高度V. myuros使该物种成为 HWSC 的不良候选者。黑麦收获时的平均种子保留率大于 50%，种子保留高度大于 30 厘米。不同物种种子保留的变异性将使 HWSC 实践的功效在 PNW 冬小麦中依赖于物种和环境。小麦L.) 种植系统。尽早收获小麦对 HWSC 的成功至关重要。