Study on the Effective Role of some Metabolites of Fluorescent Pseudomonads Bacteria in Control of Meloidogyne javanica Nematode on Tomato

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An ability of the fluorescent pseudomonad bacteria is to secrete such secondary metabolites as hydrogen cyanide, protease, salicylic acid as well as siderophore which prevent the growth of soil-habitant pathogens. Tests were done for evaluating the materials produced by the said bacteria. In the tests' cultures, P. aeruginosa strains 7NSK2, UTPF92, and UTPF86 produced the most hydrogen cyanide, protease, and salicylic acid respectively. The said strains caused the most parasitism on second-stage larvae (more than 70%) as well as parasitism on nematode egg (more than 60%) in vitro (bacterial suspension against nematode in 96-well basins) (P?0/01).Three-week-old wild type tomato seedlings were planted in plastic pots (8 cm diameter) filled with 300 g unsterilized sandy-loam, and transferred to a glasshouse. After one week, the plants were treated with bacteria by adding 30 ml of the bacterial suspension (1.9-2.1×109 CFU/ml) into soil around the root system. Control plants received 30 ml of one-fourth concentration of Ringer Solution. Two days after bacterial application, 2000 freshly hatched juveniles of M. javanica were added to the soil by making three holes around the seedlings. After 45 days past, some growth indices (dry weight of the aerial parts and root, the wet weights of the aerial parts, root and stem lengths) as well as disease indices (gall number and diameter, nematode population in soil and root along with bacteria endophyte population) were assessed. The study was arranged on the basis of a completely randomized design of ten treatments and five replications. In the roots inoculated by P. aeruginosa 7NSK2 and UTPF86 strains the most increase in total plant-growth (63% increase) was observed along with least the nematode penetration (55% decrease) into root accompanied by least gall formation (53% decrease) in comparison with the other treatments (P?0/05). Strain UTPF86 was more effective than the other treatments in control of the said nematode (P?0/05).

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