| Heilongjiang province is the major rice producing area in our country. Rice planting area of Heilongjiang province reaches 3.997 million hectares in 2014, which shares 28.11% of the total grain crops sown area of Heilongjiang. Heilongjiang is also one of the earliest provinces of herbicides application in our country. Since the 1980 s some ALS inhibitors such as pyrazosulfuron-ethyl and bensulfuron-methyl have been widely used in Heilongjiang. Scirpus juncoides Roxb is one type of perennial sedge weeds and reproduces by seeds.The peak time of their damage is consistent with rice elongation stage, so they can affect rice yield seriously.19 Scirpus juncoides Roxb biotypes collected from nine areas of Heilongjiang province were used to determine the resistant level of Scirpus juncoides Roxb to 4 common ALS inhibitors by using agar method and whole plant method. At the same time we will definite whether there is some biotypes which have cross-resistance to 4 different ALS inhibitors.Researching the differences between agar method and whole plant method by comparing the two bioassay methods. At the same time researching the resistance mechanism of Scirpus juncoides Roxb preliminarily and expliciting whether the resistance is connected with ALS, POD, SOD and CAT. The results are as follows:(1) The 19 Scirpus juncoides Roxb biotypes from 9 areas of Heilongjiang province have different resistant level to 4 different ALS inhibitors.1) After treated with pyrazosulfuron-ethyl, Shangzhi01, Shangzhi02 and Fangzheng01 developed an intermediate level of resistance; Tonghe01 developed a low level of resistance; Only Jixi01 biotype is in decreased sensitivity stage; Other 14 biotypes are sensitive to pyrazosulfuron-ethyl.2) After treated with bensulfuron-methyl, Shangzhi01 developed an intermediate level of resistance; Shangzhi02, Jixi01, Tonghe02, Fangzheng01 developed a low level of resistance; Tonghe02, Acheng01 are in decreased sensitivity stage; Other biotypes are sensitive to bensulfuron-methyl.3) After treated with penoxsulam, Shangzhi01, Shangzhi02 developed an intermediate level of resistance;Jixi01, Tonghe01 developed a low level of resistance; Qingan02,Tieli01 biotypes are in decreased sensitivity stage; Other 13 biotypes are sensitive to penoxsulam.4) After treated with pyribenzoxim,Shangzhi01, Shangzhi02 developed a low level of resistance;Tonghe01,Acheng01 biotypes are in decreased sensitivity stage respectively; Other 15 biotypes are sensitive to pyribenzoxim.(2) The cross-resistance of 19 Scirpus juncoides Roxb biotypes between 4 different ALS inhibitors. Shangzhi01,Shangzhi02 and Tonghe01 developed cross-resistance to pyrazosulfuron-ethyl, bensulfuron-methyl,penoxsulam and pyribenzoxim Fangzheng01 developed cross-resistance to pyrazosulfuron-ethyl and bensulfuron-methyl; Jixi01 developed cross-resistance to pyrazosulfuron-ethyl, bensulfuron-methyl and penoxsulam. 3.Enzymatic activities in Scirpus juncoides Roxb biotypes of different resistant level are different to pyrazosulfuron-ethyl and bensulfuron-methyl.1) The resistant level of Scirpus juncoides Roxb to pyrazosulfuron-ethyl and bensulfuron-methyl is related with non-target enzyme.Making Wuchang huangdi biotype as sensitive biotype(S),Tonghe01 biotype as medium resistant biotype(M) and Shangzhi01 biotype as high resistant biotype(R).After treated with pyrazosulfuron-ethyl,the activity of POD were all raise first and then declined.The activity of POD in R biotype was highest at the third day.The activity of POD in M and S biotypes were highest at the fifth day.7 days later,the activities of POD were similar to comparison. The activity of POD average change rate showed that R biotype(11.56%)>M biotype(6.39%)>S biotype(-4.36%)within 13 days.The activity of POD varied considerably after treated with bensulfuron-methyl.The activity of POD in R and M biotypes were higher than comparison within 13 days.The activity of POD in S biotype was higher than comparison only at the seventh day.The activity of POD average change rate showed that R biotype(46.27%)>M biotype(29.80%)>S biotype(-0.06%)within 13 days. Therefore, resistant level of Scirpus juncoides Roxb to pyrazosulfuron-ethyl and bensulfuron-methyl is related with POD.Making Wuchang huangdi biotype as sensitive biotype(S),Tonghe01 biotype as medium resistant biotype(M) and Shangzhi01 biotype as high resistant biotype(R).After treated with pyrazosulfuron-ethyl,the activity of SOD were all declined first and then raise and finally declined.The activities of SOD average change rate of S,M,R biotypes were6.12%,-23.27% and-11.64% respectively.The activity of SOD in S biotype was higher than those in M and R.This is different to the result of whole plant method.So the resistance of Scirpus juncoides Roxb to pyrazosulfuron-ethyl is not related with SOD.The activity of SOD varied considerably after treated with bensulfuron-methyl.The activity of SOD in S and M biotypes were highest at the fifth day.The activity of SOD in R biotype has been raising with time and was highest at the eleventh day.The activity of SOD average change rate showed that S biotype(29.24%)<M biotype(89.02%)<R biotype(151.63%).So SOD is one of the reasons of resistance to bensulfuron-methyl.Making Wuchang huangdi biotype as sensitive biotype(S),Tonghe01 biotype as medium resistant biotype(M) and Shangzhi01 biotype as high resistant biotype(R).After treated with pyrazosulfuron-ethyl,the activity of CAT were all raise first and then declined.The activity of CAT average change rate showed that S biotype(0.81%)<M biotype(3.2%)<R biotype(27.48%) with 13 days.So CAT is one of the reasons of resistance to pyrazosulfuron-ethyl.The activity of CAT varied considerably after treated with bensulfuron-methyl.The activity of CAT average change rate in S,M and R biotypes were-9.81%,-7.37% and 28.71% respectively.The activity of CAT average change rate in M biotype was less than 0,explained that the activity of CAT in Tonghe biotype was lower than comparison.The activity of CAT will decline because of herbicide.The activity of CAT average change rate in R biotype was higher than 0,explained that the activity of CAT has been raising to decrease harm after treated with bensulfuron-methyl.4) The resistant level of Scirpus juncoides Roxb to pyrazosulfuron-ethyl and bensulfuron-methyl is related with target enzyme.Making Wuchang huangdi biotype as sensitive biotype(S),Tonghe01 biotype as medium resistant biotype(M) and Shangzhi01 biotype as high resistant biotype(R).After treated with pyrazosulfuron-ethyl,the activity of ALS in S biotype was lower than comparison and has been inhibited obviously.The activity of ALS in M and R biotypes were twice and 2.7 times respectively of comparison at the third day.ALS in M and R always maintained high vigor.After treated with bensulfuron-methyl,the activities of ALS in S,M and R biotypes kept reducing.The activity of ALS in R biotype was highest at the first day and was 1.8 times of comparison.The activity of ALS in M biotype was highest at the third day and was 1.4 times of comparison.The activity of ALS in S biotype was lower than comparison and has been inhibited obviously.So ALS is one of the reasons of resistance to pyrazosulfuron-ethyl and bensulfuron-methyl. |
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