Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5403 1st Avenue South, Lethbridge, AB, T1J 4B1, Canada.
Sci Rep. 2022 Nov 7;12(1):18893. doi: 10.1038/s41598-022-21942-6.
Glyphosate is the most used herbicide worldwide, and is an important source of economical weed control in glyphosate-resistant crops, and conservation tillage systems, among other uses. Downy brome (Bromus tectorum L.), otherwise known as cheatgrass, is a highly invasive winter-annual grass weed in cropping systems, pastureland, and naturalized or ruderal areas in western North America. In 2021, a downy brome population remained uncontrolled following four applications of glyphosate in a glyphosate-resistant canola (Brassica napus L.) field located in Taber County, Alberta, Canada. All individuals from the subsequent generation of the population survived glyphosate treatment at the typical field rate (900 g ae ha). In dose-response bioassays, the putative glyphosate-resistant population exhibited 10.6- to 11.9-fold, 7.7- to 8.7-fold, 7.8- to 8.8-fold, and 8.3- to 9.5-fold resistance to glyphosate based on plant survival, visible control, and biomass fresh weight and dry weight, respectively, compared with two susceptible populations 21 days after treatment. Estimated glyphosate rates for 80% control of this population ranged from 2795 to 4511 g ae ha; well above common usage rates. This downy brome population represents the first glyphosate-resistant grass weed confirmed in Canada, and the second weed species exhibiting glyphosate resistance in the Canadian prairie region.
草甘膦是全球使用最广泛的除草剂，也是抗草甘膦作物、保护性耕作系统等其他用途中经济除草的重要来源。多花黑麦草（Bromus tectorum L.），又称毒草，是北美西部作物系统、牧场和自然化或废弃地中高度入侵的冬季一年生禾本科杂草。2021 年，在加拿大阿尔伯塔省塔伯县的一个抗草甘膦油菜（Brassica napus L.）田，经过四次草甘膦施药，仍有一个多花黑麦草种群未得到控制。种群的所有后代个体在典型田间用量（900 g ae ha）下都能耐受草甘膦处理。在剂量反应生物测定中，与两个敏感种群相比，假定的抗草甘膦种群在植物存活率、可见控制以及生物量鲜重和干重方面，对草甘膦的抗性分别为 10.6-11.9 倍、7.7-8.7 倍、7.8-8.8 倍和 8.3-9.5 倍。施药 21 天后，该种群对草甘膦的估计控制率为 80%，其用量范围为 2795 至 4511 g ae ha；远远高于常用用量。该多花黑麦草种群是加拿大首例确认的抗草甘膦杂草，也是加拿大草原地区第二种表现出抗草甘膦特性的杂草。
