| With the area expanding of greenhouse in northern region, root-knot nematode has infested in greenhouses and seriously affected vegetable production. At present, to control the disease, farmers usually apply chemical pesticides to irrigate vegetable root before the vegetable planting or during the growth season. Such an approach causes not only serious pollution of the soil but also the toxic chemicals to be absorbed directly by vegetables so that the vegetables are poisonous and harmful for people’s food safety and health. Therefore, we have a great need to develop some non-toxic control methods.In this thesis, two strains of the entomopathogenic fungi:Beauveria bassiana TST05 powder and Metarhizium anisopliae TSL06 fermentation broth were used to control root-knot nematodes. The study included:(1) Metarhizium anisopliae fermentation broth application including mortality experiment, indoor pot experiment, the greenhouse experiment, the fungal survival ability in the soil in the greenhouse environment, and measuring toxin components of Metarhizium fermentation broth by using gas chromatography-mass spectrometry. (2)Beauveria bassiana powder application, including the experiment on celery in winter, the experiment on cucumber in spring and summer, and fungal survival ability in the soil in the greenhouse environment. The results are as follows:1. The experiment results of the Metarhizium fermentation broth controlling root-knot nematodes in greenhouse1) Mortality experiment resultThe live nematodes were collected from the experiment greenhouse and were divided into three groups. They were treated with filtrate of Metarhizium fermentation broth, with SDAY medium, and with distilled water, respectively. After 24h treatment, the mortality of nematodes was 100% in fermentation filtrate treatment group,7.40% in medium treatment group, and 0% in distilled water treatment group.2) Experiment result in potThe celeries were planted in flower pot with the disease soil in the laboratory. Three different treatment groups were the Metarhizium fermentation broth treatment (MFB), filtrate of Metarhizium fermentation broth treatment (F-MFB), and distilled water treatment (control group). The prevention effect on root-knot nematodes was examined after three months at celery growth. The results showed that the average height of celery in MFB treatment group was higher 3.1cm than the F-MFB treatment and 6.3cm than the control group; the average plant fresh weight of celery in MFB treatment group was heavier 13.4g than the F-MFB treatment group and 6.58g than the control group; the root nodule numbers in the MFB treatment group reduced 100% comparing with the control groups, while the F-MFB group reduced 83.88%. It was concluded that Metarhizium fermentation broth has obvious control effect on the root knot nematode and the MFB treatment is better than the F-MFB treatment.3) Experiment result in greenhouseThe Metarhizium anisopliae TSL06 was prepared into fermentation borth by using fermentor. The experiment was conducted in greenhouse. The vegetable was cucumber and that was planted at the end of February. The experiment was designed three treatments, Metarhizium anisopliae fermentation broth treatment group (MFB), pesticide treatment group and blank control group. After 5 months, the numbers of root nodule on the cucumber were statisticed. The sizes of the root nodules were divided into four classes by diameter in 0-3mm,4-6mm,7-9mm, and≥10mm, respectively. Theresults showed that in MFB group, the average numbers of root nodules at each plant were 56,35,33,4 in the four size classes, respectively. While in pesticide group, the numbers were 45,9,8,1, respectively. But in control group, the numbers were 67,54,39,11, respectively. The conclusion was that MFB treatment has good controlling effect comparing with control group, however, it was not so good like the pesticide group.4) The analysis result of the toxin component of Metarhizium anisopliae fermentation brothThe fermentation borth was extracted with n-hexane and ethyl acetate as solvent. The extraction was analysised by using gas chromatography mass spectrometry. Some 20 organic small molecules as the potential toxic components were identified, such as 2,5-bis(1,1-dimethylethyl)-Phenol; Phthalic-acid,isobutyl2-pentylester; 1-ethyl-1H-indene;2,4-bis(1,1-dimethylet hyl)-Phenol;2,4-di-t-butyl-7,7-dimethyl-1,3,5-Cycloheptatriene and so on.2. The experiment results of BeauveriaBassiana powder controlling root-knot nematodes in the two greenhouses1) The celery experiment in the winter seasonThe Beauveria bassiana TST05 was prepared into powder. The experiment was conducted in greenhouse. The vegetable was celery and that was planted in early October. The fungus powder was given in soil before planting. The experiment was designed three treatments, fungus powder group, pesticide group and blank control group. After three months, plant height, root length, fresh weight, the root nodule numbers, leaf chlorophyll content and net light synthetic rate of celery were measured.The results from the greenhouse-1 showed that the celery plants grew better in the fungus powder group than that in the control group. In the fungus powder group, the plant height was taller 10.42cm than that in the pesticide group and 10.00cm than that in the control group; the plant weight in fungus powder group was heavier 48g than that in the pesticide group and 93g than that in the control group; The numbers of root-knot of celery in the fungus powder group reduced 54.9% than the control group, while in the pesticide group reduced 50.0%; the quantity of chlorophyll in the fungus powder group was more 0.05mg/g than that in the pesticide group and 0.277mg/g than that in the control group; the net photosynthetic rate in the fungus powder group was faster 0.4 mg CO2/g fresh leaf*h than that in the pesticide group and 0.367 mg CO2/g fresh leaf*h than that in the control group.In the greenhouse-2, a similar result was obtained. In the fungus powder group, the plant height was taller 2.8cm than that in the pesticide group and 12.7cm than that in the control group; the plant weight in fungus powder group was lighter 41 g than that in the pesticide group and 51g heavier than that in the control group; The numbers of root-knot of celery in the fungus powder group reduced 45.6% than the control group, while in the pesticide group reduced 41.7%; the quantity of chlorophyll in the fungus powder group was more 0.036mg/g than that in the pesticide group and 0.133mg/g than that in the control group; the net photosynthetic rate in the fungus powder group was faster 1.675 mg CO2/g fresh leaf*h than that in the pesticide group and 1.725 mg CO2/g fresh leaf*h than that in the control group.These results prove that the bassiana against root-knot nematodes have a good effect, and even better than the pesticide.2) The cucumber experiment in the spring to summer seasonThe Beauveria bassiana TST05 was prepared into powder. The experiment was conducted in greenhouse. The vegetable was cucumber and that was planted at the end of February. The fungus powder was given in soil before planting. The experiments were divided into three treatments, fungus powder group, pesticide group and blank control group. After 5 months, the numbers of root nodule on the cucumber were statisticed. The sizes of the root nodules were divided into four classes by diameter in 0-3mm,4-6mm, 7-9mm, and≥10mm, respectively. Theresults showed that in fungus powder group, the average numbers of root nodules at each plant were 63,30,22, and 5 in the four size classes, respectively. While in pesticide group, the numbers were 45,9,8, and 1, respectively. But in control group, the numbers were 67, 54,39, and 11, respectively. The conclusion was that the fungus treatment has good controlling effect comparing with control group; however, it was not so good like the pesticide group.3. The result of the fungal survival ability in the soil in the greenhouseThe spore concentration of Metarhizium fermentation borth was 1×108 spores/mL, and the spore content of Beauveria bassiana powder was 1×108 spores/g. After application in the greenhouse, the soil samples were collected once every half moon in winter, and once every month in spring and summer. The numbers of spore in the soil were measured. The results showed that in winter, the concentrations of Beauveria bassiana in the soil were 2.44 ×105,3.78×105 and 3.56×105,3.44×105,1.44×105,1.43×105 spores/g soil, in order. In spring and summer, the concentrations of Metarhizium anisopliae in the soil were 5.00×105,4.22×105,7.11×105,1.44×105, 0.11×105 spores/g soil, in order; the concentration of Beauveria bassiana in the soil were 1.56×105,10.67×105,7.12×105,2.00×105, 1.11×105,0.78×105 spores/g soil.The conclusion was that Beauveria bassiana and Metarhizium anisopliae have strong ability to survive in the greenhouse soil and the duration was 3 months. |
PDF Full Text Request