| Nematodes were isolated from root knot nematode infected plants and its rhizosphere soils collecting from the facility agricultures in different areas of Shanxi Pronvince. Through conventional morphological and molecular biological identification technique, the species and the dominant species of root knot nematode in Shanxi were studied and analyzed. A strain of fungal initially named X-16 was screened from the infected root knot nematode, and then its taxonomic status, metabolite, parasitic lethal effect, biological characteristics, fermentation conditions, fungicide development and control efficiency were studied systematically. The main results were as following:1. The main pathogens for vegetable root knot nematode of facility agriculture in Shanxi were southern root knot nematode (Meloidogyne incognita) and northern root knot nematode (Meloidogyne hapla), which were accounted for 82.6% and 17.4% of the provincial population respectively. The southern root knot nematode is the dominant population in Shanxi Province.2. A strain of fungal with parasitic function, initially named X-16, was screened from the collected samples. Through indoor test, the nematode lethal effect of this fungal to G2 larvae was analyzed, under 72 hours treatment with concentration of 5x108cfu-ml-1, the mortality was 75.80%, corrected mortality was 70.94%, and the LC50 was 7.7×108cfu·ml-1; In the potted experiment, with 1%,2% and 4% dose, the biocontrol effect to nematode was within 52%to 61%; This fungal was identified as Myrothecium verrucaria by morphological and molecular biological technique.3. The Myrothecium verrucaria strain X-16 posed quite strong parasitic function to egg, G2 larva, and adult female of cucumber root knot nematode. For the egg been parasitized, the egg shell was shrunk and sunk, the embryonic development was paused, and the parasitic eggs were covered with mycelium, the parasitic rate was 67.15% in six days. For the G2 larva parasitized by X16, initially developed tube invaded the body wall of G2 larva through macterial net formed in the surface, the parasitic rate was 82.3%in 13 days; the condensed macterial net was formed in the body wall of adult female.4. Nine active ingredients, namely T1-T9, were extracted from metabolite of Myrothecium verrucaria through reversed phase chromatography. Among them T2, T3, T6 and T8 indicated comparable stronger lethal active to root knot nematode, the corrected mortality of them were 65.75%,70.36%,79.29% and 51.49% separately under 72 hours treatment.5. Two kinds of poison compounds, butyl acetate and Pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl-) were separated and purified from three active ingredients with obvious inhibition and killing effects through GC-MS analysis. When condense was 500 ug/ml, the corrected mortality of butyl acetate and Pyrrolo [1,2-a] pyrazine-1,4-dione,hexahydro-3-(2-methylpropyl-)were 51.2% and 64.8% respectively.6. The study of biological characteristics of Myrothecium X-16 indicated that, X-16 grew best in the liquid and plate culture when the carbon nitrogen ratio was 20:1, with soluble starch as the optimum carbon source; while the carbon concentration was between one and two mol/L, which was the most conductive to the liquid culture and flat sporulation; the optimal nitrogen source inorganic sodium nitrate was conducive to the mycelium pellet formation and sporulation quantity increase in liquid culture; with lactose as carbon source, and beef extract and ammonium sulfate as the nitrogen source, which were good for spore germination of X-16; the suitable temperature for conidia germination was within 25-32℃. Suitable strain sporulation temperature was within 30℃ to 32℃, the suitable spore germination PH was 6.5 to 7.5, the suitable sporulation PH was 6.5. There was no obviously difference of colony growth in the range of PH 5-8.5.24 hours light facilitated sporulation and relatively high humidity in the culture condition facilitated the spore germination.7. The optimal condition for spore solid-liquid fermentation of Myrothecium verrucaria conidium was as following:rice culture medium; liquid culture time:60 hours, inoculation quantity:12%; material and water ratio:1:0.02-1:0.05; solid fermentation temperature:30℃ to 32℃; Sodium nitrate additive amount in solid fermentation was 1%; fermentation ended in 18 days, the suitable temperature of inoculum drying was 35℃, the drying time was 24 hours.8. Myrothecium verrucaria carrier in wettable powder, wetting agent, suspending agent, disintegrating suspension was diatomite, BTS-3, DCM-82 and DK-3 respectively. In the field, the control effect of this dosage form to melon root knot nematode was 53.7%. The strain X16 enriched quantity of the soil microorganism. The quantity of the soil fungi, actinomycetes, and bacteria were increased to 7,60, and 2 times respectively. |
PDF Full Text Request