Studies On The Resistance Of Barnyardgrass In Rice Field Of Hunan Province

Barnyardgrass is one of the most common and harmful weeds in paddy belonging to Gramineae family. Barnyardgrass can cause the reduction of rice quality and production. The major methods to preventing barnyardgrass is chemical control at present. Some barnyardgrass biotypes of different rice planting regions have got the resistance to herbicide because of the selection pressure and inheritance change? and the situation is getting more and more serious.Hunan province is an very important rice planting region of China, and it also emerges resistance frequently. The resistant biotype to Quinclorac,Butachlor and Propanil have been found in paddies of Hunan province. The level of barnyardgrass resistance have been detected in this paper, resistance mechanism and controlling have also been researched.The barnyardgrass biotypes of Yuanjiang,Miluo,Xiangyin,Nan county,Anxiang,Huarong have been collected and then the resistance to Butachlor,Pretilachlor,Prometryn,Quiclorac and Penoxsulam have been detected. The result showed that Butachlor,Pretilachlor,Prometryn and Penoxsulam had the excellent effeciecy to all biotypes while the barnyardgrass of Yuanjiang,Miluo got a high resistance to Quinclorac especially the biotype of Huarong which had the highest resistant ratio 5.06.Used barnyardgrass of Nan county as the sensitive biotype and Anxiang,Huarong as the resistant biotype, the resistance mechanism has been studied by detecting the activity ofβ-cyanoalanine synthase. The result indicated that the activity ofβ-cyanoalanine synthase of resistant biotype was 1.96 times more than sensitive biotype after spraying Quinclorac 3 days. This conclusion proved that the improvement of detoxification to cyanide byβ-cyanoalanine synthase may be one kind of the barnyardgrass resistance mechanism to quinclorac. The resistant weeds have been controlled in different methods by viarious herbicides. The herbicides combinations in the test could control most resistant weeds, this conclusion support these combinations could used by each other when one or two herbicides occurred resistance.