Bleaching of young leaf tissue is a common response to the herbicide mesotrione and varies from one application to another. To better elucidate factors that may contribute to perennial ryegrass (Lolium perenne L.) phytotoxicity from mesotrione, studies were conducted at Blacksburg, VA. Continuous field monitoring of temperature, humidity, solar radiation, soil moisture, and leaf wetness was used to elucidate environmental conditions that led to perennial ryegrass injury by mesotrione applied at 0.14 kg a.i. ha⁻¹. The study found that 2 of 17 weekly treatments caused unacceptable perennial ryegrass injury at two field sites. Ten-day temporal trends prior to mesotrione treatment showed that temperature, for one injury event, and volumetric soil water content, for the other injury event, were exclusively correlated to visually and digitally assessed perennial ryegrass injury. Both instances suggest that alleviation of suboptimal temperature or moisture with more optimal growing conditions influenced the turf injury response. Additional studies in growth chambers showed that carotenoid levels and turf phytotoxicity were strongly temperature dependent and followed a quadratic response with peak injury occurring at perennial ryegrass growth optima. Carotenoid levels decreased and perennial ryegrass injury increased in response to increased mesotrione rate. These data suggest that mesotrione is more likely to injure perennial ryegrass turf when used at higher rates and under conditions of rapid turfgrass growth.

中文翻译：

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多年生黑麦草的植物毒性随着甲基磺草酮率和促进生长的环境条件而增加

幼叶组织的漂白是对除草剂甲基磺草酮的常见反应，并且因应用而异。为了更好地阐明可能导致甲基磺草酮对多年生黑麦草 ( Lolium perenne L.) 植物毒性的因素，在弗吉尼亚州布莱克斯堡进行了研究。温度、湿度、太阳辐射、土壤水分和叶子湿度的连续现场监测被用来阐明导致多年生黑麦草被施用 0.14 kg ai ha ^{-1 的}甲基磺草酮伤害的环境条件. 该研究发现，每周 17 次处理中的 2 次在两个田间地点造成不可接受的多年生黑麦草损伤。甲基磺草酮处理前的 10 天时间趋势表明，一个损伤事件的温度和另一个损伤事件的土壤体积含水量与视觉和数字评估的多年生黑麦草损伤完全相关。这两个实例都表明，在更理想的生长条件下缓解次优温度或湿度会影响草皮损伤反应。在生长室中进行的其他研究表明，类胡萝卜素水平和草皮植物毒性强烈依赖于温度，并遵循二次响应，峰值损伤发生在多年生黑麦草的最佳生长点。随着甲基磺草酮率的增加，类胡萝卜素水平下降，多年生黑麦草损伤增加。