| Sagittaria trifolia L.is one of the main worst weeds in paddy field in Liaoning Province.In recent years,the occurrence and harm of S.trifolia in paddy field is getting more serious,shows mainly in the following three aspects: One is that S.trifolia will occur uninterruptedly during the period of paddy planting;Secondly,herbicides can not prevent the occurrence of corm breeded of S.trifolia,because of most herbicides only have inhibitory effect on the overground part,but have no effect on the underground part;Thirdly,S.trifolia is very adaptable,even if the paddy field has been ridged,it can still occur in a large area.Florpyrauxifen-benzyl is a new,synthetic auxin herbicide.In this paper,establish the baseline sensitivity of 35 S.trifolia populations to florpyrauxifen-benzyl in Liaoning Province;Determine whether there is multi-resistance between florpyrauxifen-benzyl and bensulfuron-methyl,pyrazosulfuron-ethyl and ethoxysulfuron;Investigate the reason of different sensitivity of S.trifolia to florpyrauxifen-benzyl in physiological and biochemical perspective.It can provide a reference for resistance monitoring and management of S.trifolia to florpyrauxifen-benzyl in paddy field.The main findings are as follows:1.The whole plant experiment was used to determine the sensitivity to florpyrauxifen-benzyl in all the 35 S.trifolia populations which not treated with auxin herbicide before in Liaoning Province,and established the baseline sensitivity of corm and seed breeded of S.trifolia.The results showed that the average GR50 values of corm and seed breeded of S.trifolia populations were(3.72 ± 1.406)g a.i.hm-2 and(2.44 ± 0.776)g a.i.hm-2.The sensitivity frequencies distribution of the strains was similar to Gaussian distribution.Therefore,the average GR50(3.72 ± 1.406)g a.i.hm-2 and(2.44 ± 0.776)g a.i.hm-2 can be the baseline sensitivity of corm and seed breeded of S.trifolia populations to florpyrauxifen-benzyl and can be used as a reference for monitoring the sensitivity changes of S.trifolia to florpyrauxifen-benzyl in the field.2.Established a graded risk assessment standard for resistance to florpyrauxifen-benzyl in S.trifolia populations.If RI?1,it was low risk of resistance;if 1 <RI?10,there was a history of the use of auxin herbicide in the field,the fitness of resistant biotypes was close to or higher than that of sensitive biotypes,it was moderate risk of resistance;if RI>10,there was a history of the use of auxin herbicide in the field,the fitness of resistant biotypes was close to or higher than that of sensitive biotypes,it was high risk of resistance.This test measured the sensitivity of S.trifolia which were resistant to bensulfuron-methyl,ethoxysulfuron and pyrazosulfuron-ethyl to florpyrauxifen-benzyl in Liaoning Province.The results showed that test populations were all died at the recommended dose and the resistance index of test populations to florpyrauxifen-benzyl was less than 1(RI <1)as compared with baseline sensitivity,so there was no multi-resistance between florpyrauxifen-benzyl and bensulfuron-methyl,ethoxysulfuron and pyrazosulfuron-ethyl.The resistance index of 10 populations where the historical use of auxin herbicides prevailed in Liaoning Province was less than 1(RI <1)as compared with baseline sensitivity.So,the resistance of S.trifolia population in test areas is low risk to florpyrauxifen-benzyl.3.By measuring the changes of the activity of SOD,CAT,POD and the content of MDA in S.trifolia at different times after florpyrauxifen-benzyl application,it was found that the trends of the four indexes in the less and the most sensitive S.trifolia populations were consistent,and there was no significant difference in CAT,POD activity and MDA content over time,but the less sensitive population LN-15 and LN-35 had a higher SOD activity than the most sensitive population LN-1.Therefore,the activity of SOD in less sensitive populations after florpyrauxifen-benzyl application is higher than that in the most sensitive populations may be one reason for its insensitivity to florpyrauxifen-benzyl. |
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