| Praxelis clematidea was discovered in Hong Kong in the 1980s in China.At present,it’s sporadic distribution reports in Fujian province.Based on the highway system,field investigations were used to survey each administrative district of Fujian Province.The distribution and distribution characteristics of P.clematidea were recorded in detail by using cloud data collection system and the distribution and population coverage were obtained in Fujian Province.In combination with literatures and networks resources,the distribution of P.clematidea in China was obtained based on the MaxEnt model.The effects of the extract of P.clematidea on insects,pathogenic bacteria and invasive plants were also studied.In order to control the growth and spread of P.clematidea,experiments on germination inhibition,root length inhibition and its toxicity to roots of P.clematidea were carried out for selecting the best herbicide and most suitable effective treating concentration with five kinds of herbicides.The results are as follows:(1)A total of nine prefecture-level cities which including fifteen municipal districts,twelve counties and thirty-nine prefectures were surveyed,accounted for 77.6%of the administrative districts of Fujian province.48.5%of the surveyed areas had P.clematidea distribution.According to the analysis of population coverage of P.clematidea,it could be found that the species mainly distributed in the south of Fujian and the coastal areas,especially in Zhangzhou,while the northern Fujian region found less.The prediction of the distribution area of P.clematidea based on Maxnet model was similar to that of the actual investigation.Combined with the literature,it was concluded that the minimum temperature in February had the greatest influence on the distribution of the P.clematidea,and the contribution rate of the two was 61.70%.The second was the Precipitation of driest quarter and maximum temperature in September(the contribution rate is 28.20%).The suitable area area of P.clematidea in China is 785,985 km2:high-suitable area is 162,288 km2,mid-suitable area is 279,364 km2 and low-suitable area is 334,332 km2.Suitable area of P.clematidea was 61.98%in Fujian province,among which the area of highsuitable is 45.97%.(2)The effect of P.clematidea extracts on insects was not satisfactory.After 72 h fumigation of Phyllotreta striolata by pure essential oil,the mortality rate was only 40%.The mortality was lower than 10%under fumigation treatment of essential oil which oncentration less than 0.01 g/mL.The results indicated that the fumigation effect of the P.clematidea essential oil was not satisfactory.The results of aversion experiment showed that the selection rate of P.clematidea essential oil was between 40%and 50%.There was no significant difference in the selection behavior of different concentrations of P.clematidea essential oil to P.striolata.Therefore,it could not be considered that the essential oil of P.clematidea had aversion effect on P.striolata.The results of gastric toxicity of P.clematidea aqueous extracts against P.striolata showed that the corrected mortality rates for P.striolata was 7.94%and 6.74%,respectively at concentration was 0.3 g/mL.The results indicated that the aqueous extract of P.clematidea against P.striolata had no effect on gastric toxicity.(3)It was found that the essential oil had significant inhibitory effect on the conidia of Diosporium.With the increase of the concentration of essential oil,the inhibition effect was more obvious.When the concentration of essential oil was 0.02 g/mL,the inhibition rate of germination was 43.25%and 72.2%after being treated 12 h and 24 h,respectively.The maximum inhibition rate is up to 93.65%(concentration of essential oil is 0.1 m g/mL,treated 24 h).After 24 h being treated,the inhibitory effect of EC50 oil on Oidium sp.was 0.008 g/mL,EC95 was 0.122 m g/mL.The results indicated that the essential oil could be used as a natural fungicide for the fungus.(4)The seed germination of Mimosa pudica was inhibited and the effect was enhanced with the increase concentration of aqueous extract.The inhibitory effect of dry aqueous extract on M.pudica was stronger than that of fresh extract.When treated for 7 days,the germination inhibition rates of dry and fresh aqueous extract were 84.66%and 19.26%,respectively.The results of the experiment could be used as the basis for the aqueous extract of P.clematidea to be as herbicide of plant herbicide.(5)The herbicide had germination inhibition effect on P.clematidea seed.After 10 d treatment in the control group,the germination rate of P.clematidea seeds was about 82.33%.The EC50 of 41%Glyphosate IPA Salt on the germination of P.clematidea seeds was 19.55 mg/ml,which was 5.34 times the recommended dosage(3.659 mg/ml).The EC50 was 2.08 mg/ml(dilution multiple of 480 times,which was only 1/3 of the recommended dosage of 9.091 mg/ml)after 15 d of treatment with 18%Glufosinate.The EC50 of the seeds treated with 20%Fluroxypyr was 0.67 mg/ml after treatment of 15 d,which was about 3 times of the recommended dosage of 0.22 mg/ml.The EC50 of 20%Diquat was 0.67 mg/ml after 15 d,which was 1/15-1/12 of the recommended dosage of 0.4 mg/ml-0.5 mg/ml.The EC50 of 13%MCPA-Na for 15 d to inhibit the germination of P.clematidea seeds was 0.01 mg/ml.It was 1/22 of the recommended dosage.In summary,the inhibitory effect of herbicide on the germination stage of P.clematidea seeds is as follow:13%MCPA-Na>20%Diquat>18%Glufosinate>20%Fluroxypyr>41%Glyphosate IPA Salt.(6)The toxic effect of herbicide on P.clematidea root showed that all 5 herbicides had a certain toxic effect on the root.Based on the analysis of the effective component concentration corresponding to herbicide when the mortality rate of roots was 80%,the relationship among the toxic effects of 5 herbicides on the root of P.clematidea were as follows:13%MCPANa(1.84×10-3mg/ml-3.56×10-3mg/ml)>20%Diquat(0.038 mg/ml-0.091 mg/ml)>20%Fluroxypyr(0.38 mg/ml-0.678 mg/ml)>18%Glufosinate(1.04 mg/ml-2.08 mg/ml)>41%Glyphosate IPA Salt(2.22 mg/ml-21.19 mg/ml).The results showed that the toxicity of 20%Fluroxypyr,13%MCPA-Na and 20%Diquat are very effective in poisoning the P.clematidea root.(7)Comprehensive consideration was given to the effect of herbicide on germination inhibition rate of P.clematidea seed,the toxic effect of P.clematidea root,recommended dosage and EC50.Among the 5 herbicides,the best herbicide for the control of P.clematidea were 13%MCPA-Na and 20%Diquat.Based on the survey and distribution region prediction of P.clematidea in Fujian province,it provides the practical direction for the prevention and control of the fake grass.The study on the effects of the extracts on different organisms is expected to provide a theoretical basis for the rational development of biogenic herbicides and fungicides.Through the study of the relationship between herbicide and pseudomonas,it provides a theoretical and practical basis for the prevention and treatment of P.clematidea. |
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