EFFICIENCY OF BIOLOGICAL CONTROL OF ROOT-KNOT NEMATODES IN INFECTED GRAPEVINES SEEDLING BY GENETIC IMPROVED BACTERIA.

Root-knot nematodes, Meloidogyne spp cause several losses in agriculture world-wide. However, these losses have not been clearly estimated for grapevines in Egypt. The risk to humans and environments presented by using chemical nematicides emphasizes the need for alternative tools. Rhizosphere bacteria have been reported as eco-friendly approach biological control to be effective in improving plant growth and affect nematodes reproduction. Protoplast fusion technique has been utilized as helpful tools for developing more powerful bacterial strains that combine all desired properties in one organism. The present study was conducted to increasing efficiency of biological control of root-knot nematode; M. incognita infecting grapevines as nematicidal by using protoplast fusion technique. An attempt has been made to combine between two bio-agent Bacillus thuringienesis I977 as a biocontrol and Pseudomonas aeruginosa as inducer plant growth. Under laboratory condition, 10 fusants evaluated against M. incognita J₂ appearing their efficiency as nematicidal compared to parents and control. The percentages of mortality J2 after 48 h of exposure were 83% and 84 by B. thuringienesis and P. aeruginosa suspensions, respectively, whereas the percentages of mortality caused by four fusants were achieved 100% compared with parental and control. Also, three fusants F36, F45 and F 46 and its parental were evaluated to control root-knot nematodes on grapevine seedling under greenhouse conditions. F45 was more effective on M. incognita nematode-related parameters in Superior and Thompson seedling as compared to the parents and untreated control. While F46 achieved the best reduction in Flame seedling. All fusant recorded significant (P ≤ 0.05) increase in length, fresh and dry weight of shoot, also, length and fresh weight of root and decreased the nematode-related parameters as compared their the parent and untreated control. Generally, all fusant were achieved reduction on nematodes parameters and improved grapevine seedling growth. [ABSTRACT FROM AUTHOR]