Three resistant (R) rigid ryegrass (Lolium rigidum Gaudin) populations from southern Australia (EP162, 375-14, and 198-15) with cross-resistance to thiocarbamate, chloroacetamide, and sulfonylisoxazoline herbicides displayed reduced sensitivity to the isoxazolidinone herbicides bixlozone and clomazone. Each of these R populations was exposed to two cycles of recurrent selection (RS) in which plants were treated with the field rate of bixlozone, survivors were bulk crossed, and seed was collected. After the first cycle of recurrent selection (RS1), the LD50 to bixlozone in population 198-15 increased to 17.5-fold compared with the S population and increased further to 26.9-fold after a second cycle of recurrent selection (RS2). The recurrent selection process also increased the level of resistance to bixlozone in populations EP162 and 375-14 (7.8- to 18.4-fold) compared with the S population. Phorate antagonized bixlozone and clomazone in SLR4 (34.6- and 28.1-fold increase in LD50) and both herbicides in populations EP162 (36.5- to 46.6-fold), 375-14 (71.4- to 73.9-fold), and 198-15 (86.4- to 91.5-fold) compared with the absence of phorate. The increase in LD50 of all L. rigidum RS populations when treated with phorate suggests a lack of herbicide activation is not the likely resistance mechanism to these herbicides. This research highlights the elevated risk of thiocarbamate-resistant L. rigidum populations to rapidly evolve resistance to the isoxazolidinone herbicides bixlozone and clomazone.

中文翻译：

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来自澳大利亚南部的交叉抗性硬质黑麦草（黑麦草）种群对双恶唑和异恶草酮的抗性

三抗（R）硬质黑麦草（黑麦草来自澳大利亚南部（EP162、375-14 和 198-15）对硫代氨基甲酸酯、氯乙酰胺和磺酰异恶唑啉除草剂具有交叉抗性的种群对异恶唑烷酮除草剂联苯唑酮和异恶草酮的敏感性降低。这些 R 种群中的每一个都暴露于两个循环选择 (RS) 循环中，其中植物用双唑酮的田间速率处理，幸存者被大量杂交，并收集种子。在第一个循环选择周期 (RS1) 之后，LD50与 S 群体相比，群体 198-15 中的联苯唑酮增加至 17.5 倍，并在第二轮循环选择 (RS2) 后进一步增加至 26.9 倍。与 S 种群相比，循环选择过程还增加了 EP162 和 375-14 种群对联苯唑酮的抗性水平（7.8 至 18.4 倍）。SLR4 中甲拌磷拮抗双唑酮和异恶草酮（LD 增加 34.6 倍和 28.1 倍）50) 和两种除草剂在 EP162（36.5 至 46.6 倍）、375-14（71.4 至 73.9 倍）和 198-15（86.4 至 91.5 倍）的种群中与没有甲拌磷相比。LD的增加50其中刚体乳杆菌当用甲拌磷处理时，RS 种群表明缺乏除草剂活化不是这些除草剂的可能抗性机制。这项研究强调了耐硫代氨基甲酸盐的风险升高刚体乳杆菌种群迅速进化出对异恶唑烷酮除草剂双唑酮和异恶草酮的抗性。