Study On The Application Of Pyroxsulam Controlling Weeds In Wheat Field

Wheat is one of the world’s most important food crops,the second-largest food crop after rice in our country.Sulfonanilide herbicide is one of the commonly used herbicide to control of weeds in wheat fields.Wherein,pyroxsulam is a high herbicidal activity for controlling weeds which popularization and application in China’s wheat field in recent years.but still in the initial application stage.In order to demonstrate the application value of pyroxsulam,the sulfonanilide herbicide,in wheat field in China,we took series methods such as pot experiments in greenhouse,dish-dipping,enzyme activity assays and field experiments,research and evaluation the spectrum herbicide,the herbicidal activity,the differences and mechanism of the safety of different wheat varieties with pyroxsulan,the detoxifying effect and detoxification mechanism of adding safener menfenpyr-diethyl to pyroxsulam.In order to provide theoretical basis for the pyroxsulam in the wheat fields of reasonably safe to use.The results could be summarized as follows:1.The results of greenhouse pot experiments showed that pyroxsulam had a high effective of herbicidal activity to common grass weeds and part of broadleaf weeds in wheat field,the IC50 vlues of Alopecurus aequalis,Alopecurus japonicas,Vicia sativa,Bromus japonicas,Sclerochloa kengiana and Phleum paniculatum are 1.3949,1.3717,1.0614,1.7115,1.6374 g a.i./hm2 and the IC50 values of comparison herbicide mesosulfuron-methyl to the 5 weeds are 4.6074,1.0435,1.3763,3.5912,3.0478 g a.i./hm2.2.The results of safety to various wheat varieties experiments showed that,there are significant differences among different wheat varieties.Tainong 18,Hengguan 35,Shannong 20,Liangxing 66 and Liangxing 77 showed the lower tolerance to pyroxsulan,when pyroxsulam at dose 12.5g/hm2,the plant height inhibiting rate among 19.82%~24.36% and 22.95%~38.06%;when pyroxsulam at dose 25.0g/hm2,the plant height inhibiting rate among 24.85%~32.81% and 31.92%~51.53%;Shannong 21,Shannong 22,Shannong 25,Wennong 17 and Luomai 24 showed the higher tolerance,did not appear obvious injury symptoms.But the plant length and fresh weight were inhibited of all wheat varieties treated with pyroxsulam,the results of dish-dipping showed the same trend with pot experiments in greenhouse.3.The analysis of various wheat varieties sources and safety differences showed that,there is a certain relation between sources of various wheat varieties and safety differences,especially when the sources of wheat varieties exactly the same,the safety difference is small.E.g,the root length IC50 values of Liangxing 66 and Liangxing 77(Ji 91102 and Ji 935031)are 0.37 and 0.58μg a.i./mL,which of Shannong 22 and Shannong 23(Tal and Ms2)are 6.25 and 4.66μg a.i./m L,and the tolerance of wheat is lower when Ji 935031 as one of the sources.The results of pot experiments in greenhouse showed the same trend with dish-dipping.4.The sensitive varieties Tainong 18 and the tolerant varieties Shannong 25 were chosen for enzyme assay experiments.The results showed that,the sensitivity of their ALS to pyroxsulam was not significantly different between the two tested varieties even though the difference in tolerance was significant,the IC50 values are 44.9433 and 46.2132μg a.i./L.ALS activity of the two tested varieties were inhibited when treated by pyroxsulam,wheat ALS activity could renew the inhibition rapidly which of Shannong 25 need two days and Tainong 18 need three days.The results of GSTs activity enzyme assay experiment showed that,the GSTs activity was not significantly different between the two tested varieties without pyroxsulam treated,but the relative activity of Shannong 25 in the second day reached the maximum 1.524 which of Tainong 18 reached the maximum 1.451 in the third day when treated by pyroxsulam.The results suggested that the metabolic differences of pyroxsulam by GSTs activity between the two tested wheat varieties is one of the reasons of their different tolerance to pyroxsulam.5.Safener menfenpyr-diethyl for detoxifying effect of pyroxsulam showed that,menfenpyr-diethyl has detoxifying effect to pyroxsulam.When the concentration of safener in the range of 100~400μmol/L,detoxifying effect to pyroxsulam increased with concentration increasing,reached the highest detoxifying effect in 400μmol/L,the Crop protection rate is 113.4% when pyroxsulam at dose 12.5g/hm2,after that detoxifying effect decreased with concentration increasing.The results of enzyme assay experiments showed that the safener menfenpyr-diethyl adding enhanced the relative GSTs activity of wheat,and enhanced the detoxifying metabolism of wheat.6.The field research experiments further demonstrated that,pyroxsulam had a well effective of herbicidal activity to Capsella bursa,Bromus japonicas,Phleum paniculatum,Galium aparine and Stellaria media in the wheat field,the total fresh weight efficiency 87.1%,91.7% when pyroxsulam at dose 12.5,15.0g/hm2,which is consistent with the results of indoor test.Above treatments were safe to experiment wheat Shannong 25.