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Present investigation was carried out to assess the biocontrol potential of Rhizobium leguminosarum against root-knot nematode, Meloidogyne incognita on soybean. Effect of Rhizobium strains LSI-21 and CRI-29 was assessed individually and concomitantly on reproduction of M. incognita. In vitro studies were conducted to check the effect of Rhizobium strains on egg hatching and juvenile mortality of M. incognita. Concomitant application of Rhizobium strains was more effective in reducing egg hatching and causing juvenile mortality as compared to individual treatment. In green house, Rhizobium strains were used as soil drench and seed dressing for the management of root knot nematode on soybean. It caused considerable reduction in reproduction of root knot nematode as well as improved plant growth parameters of soybean. Seed dressing showed most significant results than soil drenching. It is interesting to note that Rhizobia not only controlled reproduction of M. incognita but also an increase in plant height, fresh and dry root shoot weight was observed. It would seem that Rhizobium being a good rhizosphere organism for field and vegetable crops presumably prevent the contact of pathogenic organisms on roots.

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SummaryPasteuria penetrans is a hyperparasite with potential as a biological control agent of root-knot nematodes, Meloidogyne spp. In this study two exotic Pasteuria isolates (PP-3 and PP-J) were developed on different Meloidogyne spp. collected from different districts of Punjab, Pakistan. The development of PP-3 and PP-J on different field populations of Meloidogyne spp. showed differential infectivity in terms of nematode reproduction variables. The development of PP-3 and PP-J was maximum on tomato as compared to cucumber. It was probably due to more invasion sites for nematodes present in the tomato roots. However, a bigger root system has not always been a guarantee for development of Pasteuria on Meloidogyne spp. For successful development of Pasteuria, the key parameters are the percentage of infected females, number of endospores (female)−1 or endospores (mg root powder)−1. The results of these parameters are greater in tomato as compared to cucumber.