| Plant parasitic nematodes have become one of the important pathogen restricting crop production,which seriously threaten the safety of food production.In order to clarify the genus and distribution of the parasitic nematodes on rice in Guangxi,a investation and identification of parasitic nematodes were carried out in sixty-eight counties(district)of fourteen cities which are in Guangxi.One hundred and eighty eight samples were collected from rice rhizosphere soil.The nematodes were identified as 25 genera and family,which were Hirschmanniella,Meloidogyne and Pratylenchus,etc.Hirschmanniella spreaded widely in many regions,and the occurrence rate was 82.45%,and then Dorylaimida,its occurrence rate was 76.06%.Tylenchorhychus,Meloidogynes and Filenchus were widely distributed,and the occurrence rates were 34.04%,27.66%and 26.60%.Identification and distribution of nematodes are the foundation work for the control of plant parasitic nematode.The results will be useful guiding for further research on the control of rice parasitic nematodes in Guangxi.Recent year biological control is a hot research.As a safe and effective way,it has been widely researched and applied in controlling plant pathogenic nematodes.Microbial metabolites are one of the most effective biological control methods.In this study,Heterodera glycines J2 and Hirschmanniella were used as target test nematodes,Assay of 9 strains with potential nematicidal activity were detected in vitro.The results indicated that FCE-2,XO-2 and CQE-4 strain showed better nematicidal activity than that of other strains.(1)FCE-2 and XO-2 strain fermentation filtrates had a high nematicidal activity against H.glycines J2 and Hirschmanniella.The mortality rate of nematodes exposure to fermentation filtrates was over 70%at 72h.The mortality rate of H.glycines J2 was 91.36%and 83.51%,which was exposure to 10 times dilution of 2-week fermentation filtrates,and was 90.71%and 70.11%to Hirschmanniella exposing to 5 times dilution of 2-week fermentation filtrates.(2)The toxicity of the FCE-2 strain 2 and 3 weeks fermentation filtrates were higher than 1-week fermentation filtrates;The toxicity of the XO-2 strain 2-week fermentation filtrates were higher than land 3 weeks fermentation filtrates.(3)If mortality rate of Hirschmanniella and H.glycines J2 was same,more original fermentation filtrates was needed to kill Hirschmanniella than that of H.glycines J2 under the same condition.The nematodes exposure to FCE-2 and XO-2 fermentation filtrates 72h,the LC50 values were 90.445 1?l/ml and 76.3875?l/ml(for Hirschmanniella),and 44.9301?l/ml and 49.1746 ?l/ml(for H.glycines J2)respectively.(4)Fermentation filtrate of strain XN-2 and XO-2 had a strong hatching-inhibition effect on eggs of H.glycines,and the inhibition rate was 90.85%and 88.66%after exposed 18d respectively.CQE-4,FCE-2 and FCD-2 strain can decrease the hatching rate,less than 25%which was significantly lower than that of control(P<0.05).(5)CQE-4 strain fermentation filtrates had a strong toxic activity against H.glycines J2,and also had a strong hatching-inhibition effect on eggs(P<0.05),however,there was no significant influence on Hirschmanniella.In the pot experiment,CQE-4 strain 1-week and 2-week fermentation filtrates could inhibit the reproduction of soybean cyst nematodes in different dilution.1-week and 2-week fermentation filtrates were the best in this trial at 48 d after inoculation,and number of cysts were decreased by 76.56%and 83.52%respectively.The results provide important theoretical information for the further study of the bio-control effect and effective biocontrol agents of the strain. |
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