Susceptibility of Perennial Tropical Forage Plants to Glyphosate Herbicide in Integrated Crop-Livestock Farming Systems

ABSTRACT: The purpose of this study was to evaluate forage plant susceptibility in Urochloa ssp. and Megathyrsus maximus with two glyphosate herbicide doses, to increase the efficiency of integrated crop-livestock farming systems. A randomized block design was adopted, in a split-plot arrangement, with six replications. In the main plots, the following treatments were established: Urochloa ruziziensis, U. decumbens, U. brizantha cvs. Xaraés, BRS Piatã and BRS Paiaguás, Megathyrsus maximus cvs. Aruana and BRS Tamani; in the subplots, there were doses of glyphosate herbicide; 0.72 and 1.44 kg a.e. ha-1. The estimated control percentage was consisted of a grading scale from zero (fully living tiller) to 100 (fully dead tillers), assigned 7; 14; 21 and 28 days after herbicide application. The 0.72 kg a.e. ha-1 glyphosate dose was not effective for forage control, but it was possible to identify the most susceptible genotypes, such as U. ruziziensis and BRS Paiaguás. The 1.44 kg a.e. ha-1 dose was satisfactory in controlling (³80%) the grasses U. ruziziensis, U. brizantha cv. BRS Paiaguás and M. maximum cv. Aruana at 17, 18 and 18 days of desiccation intervals, respectively. In conclusion, the susceptibility of forage plants to herbicide glyphosate varies among species and cultivars. U. ruziziensis, BRS Paiaguás and Aruana grasses are desiccated with reduced herbicide doses and short desiccation intervals, and can contribute to the diversification of the forage used in integrated crop-livestock farming systems.

【摘要】本研究旨在探究臂形草属（Urochloa）物种与大黍（Megathyrsus maximus）对两种草甘膦（glyphosate）除草剂剂量的敏感性，以提升农牧综合种养系统的生产效率。本试验采用随机区组-裂区设计，设置6次重复。主区处理包括：臂形草属的鲁兹臂形草（Urochloa ruziziensis）、俯仰臂形草（U. decumbens）、布氏臂形草（U. brizantha）品种Xaraés、BRS Piatã、BRS Paiaguás，以及大黍品种Aruana和BRS Tamani；副区处理为草甘膦施用剂量：0.72 kg a.e.·ha⁻¹与1.44 kg a.e.·ha⁻¹。本研究以0（分蘖完全存活）至100（分蘖完全死亡）的分级评分作为防效评价标准，分别于施药后7、14、21、28天开展防效评估。结果显示，0.72 kg a.e.·ha⁻¹的草甘膦剂量对供试饲草的防效不佳，但可据此筛选出敏感性较高的基因型，如鲁兹臂形草与BRS Paiaguás。1.44 kg a.e.·ha⁻¹剂量对3个供试草种的防效可达80%以上：分别在施药后17、18、18天即可有效防除鲁兹臂形草、布氏臂形草品种BRS Paiaguás以及大黍品种Aruana。综上，不同饲草物种及品种对草甘膦的敏感性存在显著差异。鲁兹臂形草、BRS Paiaguás与Aruana饲草可通过较低除草剂剂量与较短施药后间隔实现有效防除，有助于丰富农牧综合种养系统中饲草种类的多元化。