Study On The Chemical Control Techniques Of Weeds In Rice Fields With Penoxsulam-Resistant Echinochloa Crus-galli As The Dominant Species

Echinochloa crus-galli is the most typical one of Echinochloa specie,which is the most harmful weed in rice field.It seriously affects the yield and quality of rice.Penoxsulam is the most important herbicide for controlling Echinochloa specie in recent years,because of penoxsulam possessing single target and perennial use,the Echinochloa crus-galli developed serious resistance to penoxsulam.In this study,an amino acid substitution of Ala-205-Val was found in the AXXZ-2 population,one penoxsulamresistant Echinochloa crus-galli population.The cross-and multi-herbicide resistance of the AXXZ-2 population is very serious.In order to effectively control weeds in rice fields with penoxsulam-resistant Echinochloa crus-gall,this paper aimed to screen out highly effective and safe herbicide to control the resistant Echinochloa crus-galli.On this basis,the formulation ratio screening of the compounding agent for the purpose of increasing the efficiency or expanding the herbicidal spectrum.and the field effect of new type of herbicides mixture on weed control was verified.In addition,the synergistic effect and mechanism of adjuvant on herbicides are also studied.Results are as follows:Penoxsulam-resistant Echinochloa crus-galli were used as test weeds,and penoxsulam-sensitive Echinochloa crus-galli were used as controls.The whole plant bioassay was used to determine the sensitivity to 25 herbicides,including-commonly used in paddy rice for weed control,herbicides for controlling grass weeds in other crop fields and newly developed herbicides.The safety of in other crop fields herbicides and newly developed herbicides on rice(japonica rice,indica rice)was also studied.The results showed that among the herbicides commonly used in rice fields,resistant Echinochloa crus-galli could be controlled by metamifop,propanil,pretilachlor,oxadiazon,and anilofos.Among the other crop field,isoproturon can prevent the resistant Echinochloa crus-galli and was safe to rice.Among the newly developed herbicides,pyraclonil can prevent the resistant Echinochloa crus-galli and was safe to rice.In order to effectively control weeds in rice fields with penoxsulam-resistant Echino chloa crus-galli as the dominant species,the formulation ratio studies were carried out with pretilachlor,oxadiazon,pyraclonil,propanil,and metamifop.In this chapter,penoxsulam-resistant Echinochloa crus-galli was used as the research object,the condition of simulated field efficacy test,the soil treatment formulations of pretilachlor+oxadiazon and pretilachlor+pyraclonil were evaluated by the equivalent line method,which optimal ratios were 2:1 and 8:1,respectively.According to the Golby method,the optimal ratio of stem and leaf formulations agent propanil,metamifop and carfentrazone-ethyl was 20:4.5:1.These three formulations were simulated in the field to test the efficacy of the field,and they were found to strongly inhibit the resistant Echinochloa crus-gall and other weeds in rice fields.Moreover,the field efficacy of the three formulations were tested.The recommended field doses of pretilachlor+oxadiazon,the compound of pretilachlor+pyraclonil and the compound of propanil+metamifop+carfentrazone-ethyl are 400-500,480-600 and 419.25-516 g a.i./ha,and it was confirmed that the three formulations effectively controlled other weeds in rice fields and were safe for riceThe the synergistic effects of the three adjuvants Jijian,Anngro,Agrospred Prime and Silwet806 on the four herbicides propanil,metamifop and isoproturonl were studied by whole-plant bioassay,the results showed that Anngro,Jijian,Agrospred Prime and Silwet806 had the synergistic effects on the herbicides,propanil,metamifop and isoproturonl.A suitable synergistic combination of herbicides and adjuvants is:80 g.a.i./ha metamifop with 180mL/hm2 Anngro,195g/hm2 Jijian,0.05%(v/v)Agrospred Prime and 0.15%(v/v)Silwet806 displayed the best syngergistic effect.400 g.a.i./ha propanil with 120mL/hm2 Anngro,195g/hm2 Jijian,0.1%(v/v)Agrospred Prime and 0.2%(v/v)Silwet806 displayed the best syngergistic effect.500 g.a.i./ha isoproturonl with 120mL/hm2 Anngro,195g/hm2 Jijian,0.1%(v/v)Agrospred Prime and 0.1%(v/v)Silwet806 displayed the best syngergistic effect.The synergistic effect of the four adjuvants on herbicides Agrospred Prime>Silwet806>Anngro>Jijian.At the same time,proving that adjuvants and herbicides mixed is safe for rice.Furthermore,a representative combination of propanil and Agrospred Prime was further selected to explore its synergistic mechanism.Mixing with Agrospred Prime can significantly reduce the contact angle and surface tension of propanil,reduce the content of chlorophyll in plants and lead to the increase of antioxidase activities in plants.This showed that weeds were inhibited seriously,which may be one of the mechanisms of synergism.