Separation of chiral enantiomers and the dissipation of rac-metolachlor and S-metolachlor in soil were evaluated using achiral high-performance liquid chromatography (HPLC) and chiral gas chromatography (GC) methods. ...Separation of chiral enantiomers and the dissipation of rac-metolachlor and S-metolachlor in soil were evaluated using achiral high-performance liquid chromatography (HPLC) and chiral gas chromatography (GC) methods. Under the experimental conditions the possible metabolite was considered to be N-(2-ethyl-6-methyl-phenyl)-2-hydroxy-acetamide. Because of the presence of two chiral elements (asymmetrically substituted carbon and chiral axis), the baseline separation of metolachlor enantiomers was not achieved. S-metolachlor degraded faster in soil than rac-metolachlor. After a 42-day incubation, 73.4% of rac-metolachlor and 90.0% of S-metolachlor were degraded. However, due to the absence of biological processes the degradation process in sterilized soil showed no enantioselectivity. The results indicated that enantioselective degradations could greatly affect the environmental fate of metolachlor and should be considered when the environmental behavior of these compounds was assessed.展开更多
Diclosulam and flumioxazin applied preemergent (PRE) results in direct peanut exposure to these herbicides prior to seedling emergence. Flumioxazin has been reported to induce injury in adverse weather (</span>&...Diclosulam and flumioxazin applied preemergent (PRE) results in direct peanut exposure to these herbicides prior to seedling emergence. Flumioxazin has been reported to induce injury in adverse weather (</span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> cool-wet soil conditions) at crop emergence. Research at Ty Ty and Plains, Georgia evaluated the physiological effects of PRE herbicides to emerging peanut in 2018 and 2019. Peanut seed with variable germination and different planting dates were evaluated as additional factors. Peanut plant physiological measurements included electron transport (ETR), net assimilation rate (</span><i><span style="font-family:Verdana;">A</span></i><sub><span style="font-family:Verdana;">net</span></sub><span style="font-family:Verdana;">), quantum yield of PSII (Φ</span><sub><span style="font-family:Verdana;">PSII</span></sub><span style="font-family:Verdana;">), and stomatal conductance to water vapor (GSW). Data were obtained from V3 to R1 peanut growth stages using a LiCOR 6800, along with stand counts and plant width measures. In 2018, diclosulam reduced peanut ETR when measured across multiple growing degree days (GDD) after planting, compared to the nontreated control (NTC). Flumioxazin reduced peanut ETR compared to the NTC, at several sample timings for each planting date. In 2018 and 2019 at both locations, flumioxazin impacted </span><i><span style="font-family:Verdana;">A</span></i><sub><span style="font-family:Verdana;">net</span></sub><span style="font-family:Verdana;"> less than ETR, but was consistently similar to/or greater than the NTC. Peanut Φ</span><sub><span style="font-family:Verdana;">PSII</span></sub><span style="font-family:Verdana;"> responded similarly as </span><i><span style="font-family:Verdana;">A</span></i><sub><span style="font-family:Verdana;">net</span></sub><span style="font-family:Verdana;"> at each location and yr. GSW was variable in both years</span></span><span style="font-family:Verdana;">;</span><span style="font-family:Verdana;">however flumioxazin treated plants had higher GSW rates than other treated plants. Peanut stand counts, plant widths, and pod yields noted few differences compared to the physiological measures. Though some peanut plant physiological differences were noted when measured at varying GDD’s after planting with the different PRE treatments, planting date, and seed vigor, no specific trends were observed. Growers will often observe peanut injury from flumioxazin early in the season. However, it is transient and does not affect yield.展开更多
2017年和2018年采用田间小区药效试验的方法,评价52%精异丙甲草胺·丙炔氟草胺悬乳剂对花生田一年生杂草的防治效果和对花生的安全性。结果表明,52%精异丙甲草胺·丙炔氟草胺悬乳剂能有效防除河北省花生田一年生杂草,如马唐、...2017年和2018年采用田间小区药效试验的方法,评价52%精异丙甲草胺·丙炔氟草胺悬乳剂对花生田一年生杂草的防治效果和对花生的安全性。结果表明,52%精异丙甲草胺·丙炔氟草胺悬乳剂能有效防除河北省花生田一年生杂草,如马唐、牛筋草、马齿苋、反枝苋、酸浆等,适宜剂量为780~975 g a.i./hm^(2),对杂草鲜重总防效为88.2%~100.0%,防效均高于丙炔氟草胺和精异丙甲草胺2个单剂。52%精异丙甲草胺·丙炔氟草胺悬乳剂对花生出苗、生长和发育无影响,产量比空白对照增产30%以上,该药剂在花生播后苗前施药对花生安全。展开更多
评价草铵膦、丙炔氟草胺及其混剂对砂糖橘园杂草的防除效果及其安全性。田间试验结果表明,用600 g a. i./hm^2200 g/L草铵膦水剂、675 g a. i./hm^245%丙炔氟草胺悬浮剂及396 g a. i./hm^266%氟草·草铵膦可湿性粉剂喷施14 d后,对...评价草铵膦、丙炔氟草胺及其混剂对砂糖橘园杂草的防除效果及其安全性。田间试验结果表明,用600 g a. i./hm^2200 g/L草铵膦水剂、675 g a. i./hm^245%丙炔氟草胺悬浮剂及396 g a. i./hm^266%氟草·草铵膦可湿性粉剂喷施14 d后,对砂糖橘园阔叶杂草和禾本科杂草的鲜质量防效均在95%以上,因此值得在南方砂糖橘园推广使用,尤其是混剂能改善对阔叶类杂草的防效。进一步用叶绿素荧光技术测定了3种药剂低于正常使用剂量喷雾对砂糖橘叶片的影响,结果表明3种药剂对砂糖橘叶绿素荧光参数均有不同程度的影响,其危害程度表现为66%氟草·草铵膦可湿性粉剂> 45%丙炔氟草胺悬浮剂> 200 g/L草铵膦水剂。因此,3种试验药剂均存在一定的安全风险,在使用过程中应避免药液飘移至果树上。展开更多
基金Supported by the National Science Fund for Distinguished Young Scholars (No. 20225721) and the National Natural Science Foundation of China (No. 30270767).
文摘Separation of chiral enantiomers and the dissipation of rac-metolachlor and S-metolachlor in soil were evaluated using achiral high-performance liquid chromatography (HPLC) and chiral gas chromatography (GC) methods. Under the experimental conditions the possible metabolite was considered to be N-(2-ethyl-6-methyl-phenyl)-2-hydroxy-acetamide. Because of the presence of two chiral elements (asymmetrically substituted carbon and chiral axis), the baseline separation of metolachlor enantiomers was not achieved. S-metolachlor degraded faster in soil than rac-metolachlor. After a 42-day incubation, 73.4% of rac-metolachlor and 90.0% of S-metolachlor were degraded. However, due to the absence of biological processes the degradation process in sterilized soil showed no enantioselectivity. The results indicated that enantioselective degradations could greatly affect the environmental fate of metolachlor and should be considered when the environmental behavior of these compounds was assessed.
文摘Diclosulam and flumioxazin applied preemergent (PRE) results in direct peanut exposure to these herbicides prior to seedling emergence. Flumioxazin has been reported to induce injury in adverse weather (</span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> cool-wet soil conditions) at crop emergence. Research at Ty Ty and Plains, Georgia evaluated the physiological effects of PRE herbicides to emerging peanut in 2018 and 2019. Peanut seed with variable germination and different planting dates were evaluated as additional factors. Peanut plant physiological measurements included electron transport (ETR), net assimilation rate (</span><i><span style="font-family:Verdana;">A</span></i><sub><span style="font-family:Verdana;">net</span></sub><span style="font-family:Verdana;">), quantum yield of PSII (Φ</span><sub><span style="font-family:Verdana;">PSII</span></sub><span style="font-family:Verdana;">), and stomatal conductance to water vapor (GSW). Data were obtained from V3 to R1 peanut growth stages using a LiCOR 6800, along with stand counts and plant width measures. In 2018, diclosulam reduced peanut ETR when measured across multiple growing degree days (GDD) after planting, compared to the nontreated control (NTC). Flumioxazin reduced peanut ETR compared to the NTC, at several sample timings for each planting date. In 2018 and 2019 at both locations, flumioxazin impacted </span><i><span style="font-family:Verdana;">A</span></i><sub><span style="font-family:Verdana;">net</span></sub><span style="font-family:Verdana;"> less than ETR, but was consistently similar to/or greater than the NTC. Peanut Φ</span><sub><span style="font-family:Verdana;">PSII</span></sub><span style="font-family:Verdana;"> responded similarly as </span><i><span style="font-family:Verdana;">A</span></i><sub><span style="font-family:Verdana;">net</span></sub><span style="font-family:Verdana;"> at each location and yr. GSW was variable in both years</span></span><span style="font-family:Verdana;">;</span><span style="font-family:Verdana;">however flumioxazin treated plants had higher GSW rates than other treated plants. Peanut stand counts, plant widths, and pod yields noted few differences compared to the physiological measures. Though some peanut plant physiological differences were noted when measured at varying GDD’s after planting with the different PRE treatments, planting date, and seed vigor, no specific trends were observed. Growers will often observe peanut injury from flumioxazin early in the season. However, it is transient and does not affect yield.
文摘2017年和2018年采用田间小区药效试验的方法,评价52%精异丙甲草胺·丙炔氟草胺悬乳剂对花生田一年生杂草的防治效果和对花生的安全性。结果表明,52%精异丙甲草胺·丙炔氟草胺悬乳剂能有效防除河北省花生田一年生杂草,如马唐、牛筋草、马齿苋、反枝苋、酸浆等,适宜剂量为780~975 g a.i./hm^(2),对杂草鲜重总防效为88.2%~100.0%,防效均高于丙炔氟草胺和精异丙甲草胺2个单剂。52%精异丙甲草胺·丙炔氟草胺悬乳剂对花生出苗、生长和发育无影响,产量比空白对照增产30%以上,该药剂在花生播后苗前施药对花生安全。
文摘评价草铵膦、丙炔氟草胺及其混剂对砂糖橘园杂草的防除效果及其安全性。田间试验结果表明,用600 g a. i./hm^2200 g/L草铵膦水剂、675 g a. i./hm^245%丙炔氟草胺悬浮剂及396 g a. i./hm^266%氟草·草铵膦可湿性粉剂喷施14 d后,对砂糖橘园阔叶杂草和禾本科杂草的鲜质量防效均在95%以上,因此值得在南方砂糖橘园推广使用,尤其是混剂能改善对阔叶类杂草的防效。进一步用叶绿素荧光技术测定了3种药剂低于正常使用剂量喷雾对砂糖橘叶片的影响,结果表明3种药剂对砂糖橘叶绿素荧光参数均有不同程度的影响,其危害程度表现为66%氟草·草铵膦可湿性粉剂> 45%丙炔氟草胺悬浮剂> 200 g/L草铵膦水剂。因此,3种试验药剂均存在一定的安全风险,在使用过程中应避免药液飘移至果树上。