Control of barnyardgrass susceptible and resistant to imidazolinones at different temperature regimes before and after imazethapyr application

ABSTRACT Environmental conditions can influence herbicide metabolism and interfere with the evolution of weed resistance. This study aimed to evaluate the effect of thermal regimes on the control of barnyardgrass (Echinochloa crus-galli) susceptible and resistant to herbicides of the imidazolinones chemical group. Factor A (biotypes) consisted of one biotype that is susceptible and one that is resistant to imazethapyr; factor B (dose) comprised six imazethapyr doses between 0 and 800 g ha-1 for the resistant biotype and between 0 and 100 g ha-1 for the susceptible biotype; factor C (temperature) consisted of four thermal regimes (16/16 ºC, 25/25 ºC, 16/25 ºC and 25/16 ºC) to which the plants were submitted before and after the herbicide application. Concerning the resistant biotype, the highest control levels were observed in the thermal regimes with temperature fuctuation, especially at 25/16 ºC. At the recommended imazethapyr dose (100 g ha-1), the herbicide resulted in a control level over 90 % at 25/16 ºC and less than 50 % at 16/16 ºC, in the resistant biotype. The shoot dry mass was reduced by more than 80 % at 25/16 ºC and 16/25 ºC and less than 30 % at 16/16 ºC. The temperature conditions to which the plants are subjected in the pre- and post-application period interfere with the level of imazethapyr resistance in barnyardgrass.

摘要 环境条件可影响除草剂代谢，并干扰杂草抗药性的演化进程。本研究旨在探究温度制度对咪唑啉酮类（imidazolinones）除草剂敏感及抗性稗草（*Echinochloa crus-galli*）防除效果的影响。因素A（生物型）设置两个稗草生物型：其一对咪唑乙烟酸（imazethapyr）敏感，另一对其产生抗性；因素B（施药剂量）设置6个咪唑乙烟酸剂量梯度：抗性生物型的剂量范围为0~800 g·ha⁻¹，敏感生物型为0~100 g·ha⁻¹；因素C（温度）设置4种温度制度：16/16 ℃、25/25 ℃、16/25 ℃及25/16 ℃，分别在除草剂施药前后对植株进行处理。对于抗性生物型，温度波动的温度制度下防除效果最佳，尤以25/16 ℃处理组最为显著；在咪唑乙烟酸推荐剂量（100 g·ha⁻¹）下，抗性生物型的稗草防除效果在25/16 ℃时可达90%以上，而在16/16 ℃时仅为50%以下。25/16 ℃与16/25 ℃处理下，稗草地上部干重降幅均超过80%，而16/16 ℃处理下降幅不足30%。施药前后植株所处的温度条件，会干扰稗草对咪唑乙烟酸的抗药性水平。