Study On The Resistance Of Beckmannia Syzigachne To Quizalofop-p-ethyl In Rape Field

As a major weed species in rape field, Beckmannia syzigachne has a strong impact on yield and quality of rape. On the basis of collecting Beckmannia syzigachne populations in rape field of Hunan Province, dormancy breaking and germination characteristics of Beckmannia syzigachne was studied. Then, indoor bioassay method was conducted to determine quizalofop-p-ethyl resistance of Beckmannia syzigachne, and the mechanism of quizalofop-p-ethyl resistance was studied. Finally, preliminary study on chemical control of quizalofop-p-ethyl resisitant Beckmannia syzigachne was carried, which would provide scientific basis for field control of quizalofop-p-ethyl resistant Beckmannia syzigachne. The results were as follows:Dormancy breaking and germination characteristics of Beckmannia syzigachne was studied. The results showed that GA3 and KNO3 treatment could effectively break dormancy of Beckmannia syzigachne, ETH and HC1 treatment had also certain effect on dormancy breaking of Beckmannia syzigachne seeds, but not so effective as GA3 and KNO3 treatment.The result of germination characteristics study showed that pH had little effect on germination of Beckmannia syzigachne seeds. Light had certain effect on germination of Beckmannia syzigachne seeds,germination rate of Beckmannia syzigachne seeds under all-day light was lower than light-dark alternation. The optimum temperature for Beckmannia syzigachne seed germination was 10～15℃. The highest seedling emergence was observed when Beckmannia syzigachne seeds were placed on the soil surface or no more that 2 cm depth of burial.The resistant level of ten Beckmannia syzigachne biotypes to quizalofop-p-ethyl were determined by seed bioassay and whole plant bioassay methods, respectively.The results showed that different bioassays may have different resistance level.In this paper,resistance level of Beckmannia syzigachne biotypes determined by seed bioassay were a little higher that that determined by whole plant bioassay method.The results of whole plant bioassay showed that IC50 value of Liuyang Yongan biotype was 82.043 g/hm2,and its relative resistance ratio was highest of 23.60. Relative resistance ratio of other 8 biotypes were between 2.48～8.53 of low resistance level.Resistance mechanism of Beckmannia syzigachne to quizalofop-p-ethyl was studied.The results showed that GST activity of resisitant Beckmannia syzigachne biotype was significantly higher than sensitive biotypes. SOD activity of resisitant Beckmannia syzigachne biotype was significantly higher than sensitive biotypes. POD activity of resisitant Beckmannia syzigachne biotype had no sigficance with sensitive biotypes. CAT activity of resisitant Beckmannia syzigachne biotype was higher than sensitive biotypes after quizalofop-p-ethyl treatment, no significant difference existed in 1～5days after quizalofop-p-ethyl treatment in resistant and sensitive biotypes,and CAT activity of resisitant Beckmannia syzigachne biotype was significantly higher than sensitive biotype in 7-14days after quizalofop-p-ethyl treatment.MDA content in resistant biotype was significantly lower that sensitive after quizalofop-p-ethyl treatment.It can be seen quizalofop-p-ethyl resistance of Beckmannia syzigachne may be related to factors like enhance of GST,SOD and CAT activity.10% Pyribambenz-isopropyl SC,10% Pyribambenz-propyl EC,41%glyphosate AS, 20% napropamide EC,10.8% haloxyfop-R-methyl EC,99%acetochlor EC and 24%clethodim EC were selected as good herbicides controlling quizalofop-p-ethyl resistant Beckmannia syzigachne, stem control effect and fresh weight control effect of these herbicides were all above 90%.Through reasonable rotation of these herbicides, quizalofop-p-ethyl resistant weeds could be effectively controlled.