Study Of Ricinus Communis Extracts And Paecilomyces Lilacinus On The Biological Control Of Meloidogyne Incognita

Root-knot nematodes (Meloidogyne spp.) always leads to great economic loss in agricultural crops worldwide. Environmental problems caused by chemical control stimulated the research for alternative control strategies. As a nematicidal plant, Ricinus communis was efficiently against to root-knot nematodes. Several attempts had been made to use antagonistic fungi to control root-knot nematodes. The egg-parasitical fungus Paecilomyces lilacinus has been studied over the past two decades for potential usage as control agent for plant parasitic nematodes.The impacts of Ricinus communis extracts and Paecilomyces lilacinus on the nematocidal activity, the control of Meloidogyne incognita, the soil nutrients and soil microbial biomass with the nematocidal activity test and pot experiment were studied. The results showed were as follows.The ricinine and Ricinus communis water extracts could highly poison Meloidogyne incognita. When the concentration of ricinine reached 2000 mg·L-1 by 48 hours teratment, the nematocidal activity was the strongest among all treatments, which could lead to 91.5% of corrected mortality for Meloidogyne incognita, and the LC50 was 585.2 mg-L-1. When the concentration of Ricinus communis water extracts achieved 100 g·L-1 by 48 hours teratment, the nematocidal activity was the strongest, which could lead to 83.5% of corrected mortality for Meloidogyne incognita, and the LC50 was 18.3 g·L-1. Then with the treatment of the ricinine. Ricinus communis water extracts and plant powder of Ricinus communis leaves to Meloidogyne incognita, respectively, the results could be showed as follows, the mean number of root-knots, which were significantly lower than the control 37, were 18,21 and 23, respectively, and the root length of tomato increased 46.8%.34.5% and 33.8%, the plant height increased 33.5%. 22.6% and 15.8%. and the fresh mass increased 41.4%, 18.9% and 10.1%, compared with the control, respectively. The results above indicated that Ricinus communis extracts could release the harm of Meloidogyne incognita and also had significant effects against Meloidogyne incognita in pot tomato test.The ricinine had no effects on bourgeoning spores of Paecilomyces lilacinus, but the ricinine and Paecilomyces lilacinus had highly nematocidal activity. With the ricinine treatment, the inhibition rate of egg hatching and mortality of the second stage juveniles of Meloidogyne incognita, which were significantly higher than that of the control treatment, were 61.7% and 69.0%, respectively. Then with the treatment of combination of ricinine and Paecilomyces lilacinus to the Meloidogyne incognita, the results could be showed as follows, the mean number of root-knots were 15, which were significantly lower than the control 37. The increase rate of plant height, fresh mass and root length of tomato were significantly higher than that of the control treatment, which were increased 38.5%, 44.0%and 57.0%, respectively. And the results above indicated that Ricinus communis extracts and Paecilomyces lilacinus could release the harm of Meloidogyne incognita and also had significant effects against Meloidogyne incognita in pot tomato test.Soil nutrients and soil microbial biomass were all higher than the control with the treatment of Ricinus communis extracts and Paecilomyces lilacinus. Soil available nitrogen with the combination of plant powder and spores reached the maximum value of 111.3 mg·kg-1. Soil available phosphorus with the treatment of Ricinus communis water extracts reached the maximum value of 26.9 mg·kg-1. Soil available potassium and soil organic matter with the plant powder of Ricinus communis leaves all reached the maximum value of 128.1 mg·kg-1 and 11.9 g·kg-1. respectively. Soil microbial biomass carbon and nitrogen with the spores of Paecilomyces lilacinus all reached the maximum value of 122.6 mg·kg-1 and 55.0 mg·kg-1, respectively. There were positive correlations among soil microbial biomass carbon, nitrogen and soil nutrients. Also, soil microbial biomass carbon exhibited a significant positive correlation with soil microbial biomass nitrogen. These results demonstrated that the application of Ricinus communis extracts and Paecilomyces lilacinus could increase soil microbial biomass and improve soil fertility.