The Response of Different Weed Species to Glyphosate Using Ammonium Sulfate and Hard Water

ABSTRACT: Water hardness antagonism and the effect of ammonium sulphate (AMS) on efficacy of glyphosate have been well documented. However conflicting results between weed species were noted by the authors. Greenhouse experiments were conducted twice at the Ferdowsi University of Mashhad in a randomized complete block design with a factorial arrangement and three replications during 2014-2015. Four experiments were arranged separately on cypress (Kochia scoparia), redroot pigweed (Amaranthus retroflexus), little seed canary grass (Phalaris minor) and winter wild oat (Avena ludoviciana) using ammonium sulphate and deionizad water and in the presence of different salts, (i.e. NaHCO3, CaCO3, MgCl2 and CaCl2 at 500 ppm) against three doses of glyphosate (256.25, 512.5 and 1,025 g a.i. ha-1), with and without ammonium sulphate (AMS) as adjuvant (2% w/v). The results showed the application of AMS overcomes the inhibitory effects of salts in the spray solution in tested species. The degree of effectiveness in A. retroflexus was more than A. ludoviciana and P. minor. Glyphosate with AMS caused reduction in dry matter in grasses from 0.34 to 0.28 g, while glyphosate toxicity in A. retroflexus with AMS was 100 percent and all of the plants were destroyed (0.82 to 0 g). The application of AMS in overcoming the inhibitory effects of water hardness had no effect on K. scoparia control. However, Increasing AMS could overcome the inhibitory effects of hard water in the spray solution on glyphosate efficacy in A. retroflexus and K. scoparia, but it had no effect on tested grassy weeds. We may conclude that glyphosate work differently on weed species using AMS and hard water.

摘要：水硬度拮抗作用及硫酸铵（ammonium sulphate，AMS）对草甘膦（glyphosate）药效的影响已有充分研究报道。然而本研究团队观察到，不同杂草物种间的试验结果存在分歧。2014-2015年间，研究人员在马什哈德费尔多西大学（Ferdowsi University of Mashhad）开展了2组温室试验，试验采用随机完全区组设计、因子排列方案，设置3次重复。研究分别针对4种杂草独立设置试验：地肤（Kochia scoparia）、反枝苋（Amaranthus retroflexus）、小籽雀麦（Phalaris minor）及冬野燕麦（Avena ludoviciana）。试验以硫酸铵与去离子水为基础处理，额外添加浓度为500 ppm的不同盐类（即碳酸氢钠NaHCO3、碳酸钙CaCO3、氯化镁MgCl2及氯化钙CaCl2），同时设置3个草甘膦剂量梯度：256.25、512.5及1025 g 有效成分·公顷⁻¹，分别添加与不添加2%质量体积比的硫酸铵（AMS）作为助剂。试验结果表明，添加AMS可抵消喷雾液中盐类对供试杂草的抑制作用。反枝苋的药效提升幅度高于冬野燕麦与小籽雀麦。添加AMS的草甘膦可使禾本科杂草的干物质重量从0.34 g降至0.28 g；而反枝苋在添加AMS后，草甘膦毒杀效率达100%，所有植株均被完全杀灭（干物质重量从0.82 g降至0 g）。AMS对缓解水硬度抑制作用的效果对地肤防除无显著影响。不过，提高AMS用量可缓解硬水喷雾液对反枝苋与地肤草甘膦药效的抑制作用，但对供试禾本科杂草无此效果。综上可知，在使用AMS与硬水的情况下，草甘膦对不同杂草物种的作用效果存在差异。