苏门白酒草对草甘膦等除草剂的多抗性检测及防治药剂筛选

苏门白酒草Conyza sumatrensis是中国华南地区常见的阔叶杂草，在果园和非耕地常造成严重危害。本研究采用整株剂量反应法，明确了采自广东省广州市的苏门白酒草疑似抗性种群 (GZ-R) 对草甘膦、百草枯和敌草快的抗性水平，比对了GZ-R种群和采自广东省清远市的敏感对照种群 (QY-S) 的草甘膦靶标酶基因EPSPS2片段的差异，并测定了灭草松、氯氟吡氧乙酸等5种茎叶处理剂对不同叶龄苏门白酒草的室内防除效果。结果表明:GZ-R种群对草甘膦和百草枯分别产生了中等水平和高水平抗性，并已对敌草快产生交互抗性，3种药剂对GZ-R种群的LD₅₀值分别是对QY-S种群LD₅₀值的7.2、72.3和6.6倍；与QY-S种群相比，GZ-R种群的EPSPS2基因106位由脯氨酸突变为苏氨酸。在灭草松、氯氟吡氧乙酸或2甲4氯钠推荐剂量下，于4~5叶期施药，苏门白酒草死亡率均为100%，但于6~7叶期和10~12叶期施药，苏门白酒草死亡率显著下降至44.4%~91.7%；而在草铵膦或苯嘧磺草胺推荐剂量下，不同叶龄期施药苏门白酒草的死亡率均为100%，因此在植株生长早期可使用草铵膦和苯嘧磺草胺防除已对草甘膦和百草枯等除草剂产生抗性的苏门白酒草。

Multiple resistance detection to glyphosate and other herbicides in Conyza sumatrensis and the evaluation of chemical control herbicides

In South China, Conyza sumatrensis is a common broadleaf weed, and often causes serious damage in orchards and uncultivated areas. Whole plant dose-response experiments were conducted to evaluate the resistance levels of the suspected resistant population (GZ-R, collected from Guangzhou, Guangdong Province) to glyphosate, paraquat and diquat. The fragments of the glyphosate target enzyme gene, EPSPS2, were sequenced and compared between GZ-R and the susceptible population (QY-S, collected from Qingyuan, Guangdong Province). In addition, the control efficacies of five post-emergence herbicides (including bentazone, fluroxypyr, etc) on GZ-R and QY-S population at different leaf stages were also assessed. The results showed that GZ-R population had evolved moderate and high levels of resistance to glyphosate and paraquat, respectively. In addition, GZ-R population had also evolved cross resistance to diquat. The LD₅₀ values of GZ-R population to glyphosate, paraquat and diquat were 7.2, 72.3 and 6.6 folds than QY-S population, respectively. Compared to QY-S population, the mutation of EPSPS2 site 106 from Pro to Thr was found in GZ-R population. At the recommended field dosages, when bentazone, fluroxypyr and MCPA-sodium were sprayed at the 4-5 leaf stage, the mortality rate of C. sumatrensis plants was 100%. However, the mortality rate declined significantly to 44.4%-91.7% when the above three herbicides were sprayed at the 6-7 and 10-12 leaf stages. In comparison, at the the recommended field dosages of glufosinate-ammonium and saflufenacil, the mortality rates maintained at 100% regardless of the leaf stage. In summary, glufosinate-ammonium and saflufenacil can be applied for controlling glyphosate- and/or paraquat- resistant C. sumatrensis at its early growth stage.