Recently, glyphosate-resistant Italian ryegrass (Lolium multiflorum Lam.) was found on rice paddy levees in a western region of Shizuoka Prefecture, Japan. Naturalized populations of Italian ryegrass are frequently infected with fungal Epichloe endophytes. Endophytes often confer benefits to their host grasses. This study investigated the influence of five weed management treatments on glyphosate resistance and endophyte infection in Italian ryegrass that was growing on paddy levees where glyphosate-resistant individuals were dominant. The weed management treatments were: (i) mowing once before the grass flowered; (ii) mowing once during flowering; (iii) mowing twice during flowering; (iv) glyphosate application before flowering; and (v) no treatment. The seeds were collected from the treatment plots in 2013 and 2014. The seeds were examined for endophyte infection and the seedlings that had been grown from the seeds were tested for the frequency of glyphosate resistance. The seedlings that had been derived from the glyphosate treatment showed higher frequencies of glyphosate resistance than those seedlings that had been derived from all the other treatments. Endophytes were found in all populations of the seeds from the paddy levees, with higher infection rates in the seeds that had been derived from the glyphosate treatment and the twice-mowed treatment. There was a significant relationship between the endophyte infection frequency in the seeds and glyphosate resistance in the seedlings that had been grown from the same populations. The results indicate that where glyphosate herbicides are frequently used, selection for glyphosate-resistant Italian ryegrass occurs, and along with this, the frequency of endophyte infection also increases.

中文翻译：

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杂草管理措施对归化意大利黑麦草（Lolium multiflorum）草甘膦抗性和内生菌感染的影响

最近，在日本静冈县西部地区的稻田堤坝上发现了抗草甘膦的意大利黑麦草（Lolium multiflorum Lam.）。归化的意大利黑麦草种群经常感染真菌 Epichloe 内生菌。内生菌通常会给寄主草带来好处。本研究调查了五种杂草管理处理对生长在稻谷堤坝上的意大利黑麦草的草甘膦抗性和内生菌感染的影响，其中草甘膦抗性个体占优势。杂草管理处理是： (i) 在草开花前割一次；(ii) 开花期间割草一次；(iii) 开花期间割草两次；(iv) 开花前施用草甘膦；(v) 没有治疗。种子收集自 2013 年和 2014 年的处理地块。检查种子的内生菌感染，并测试从种子长出的幼苗的草甘膦抗性频率。来自草甘膦处理的幼苗比来自所有其他处理的幼苗表现出更高的草甘膦抗性频率。在来自稻田堤坝的所有种子种群中都发现了内生菌，其中来自草甘膦处理和两次割草处理的种子的感染率更高。种子中的内生菌感染频率与来自相同种群的幼苗的草甘膦抗性之间存在显着关系。结果表明，在经常使用草甘膦除草剂的地方，