Evaluation of predation potency of predatory nematodes and the influence of organic amendments on nematode communities and growth of tomato

Abstract

In the experiment designed to evaluate the predation potency of predatory nematodes, Iotonchus indicus and Mylonchulus minor under laboratory condition against J2 of Meloidogyne incognita (Kofoid and White) Chitwood as prey, mortality of J2 was highest when fifteen numbers of predators were used. The mortality of M. incognita increased with increase in number of predators. Most effective predator was M. minor, when compared to I. indicus. Second experiment with soil amendments, showed that neem cake @ 50 g pot^-1 was the superior in reducing the final population of M. incognita (88.38%) followed by poultry manure @ 50 g pot^-1 (85.50%), castor cake @ 50 g pot^-1(81.07%), saw dust @ 50 g pot^-1 (73.89%) and Gliricidia leaves @ 100 g pot^-1 (62.99%) compared to untreated. Similar trend was noticed with other plant parasitic nematodes. Neem cake was the most effective treatment in increasing the final population of I. indicus (333.33%), M. minor (278.90%) and predatory dorylaimids (125.00%) followed by poultry manure. Neem cake was the superior treatment in reducing the formation of root galls (11.25) and egg masses (7.75) in tomato plant infected with M. incognita followed by soil amendment with poultry manure. The shoot length (71.55cm), root length (12.93cm), shoot weight (23.15g) and root weight (6.88g) of tomato was highest when amended with neem cake followed by poultry manure. The increase in the population of predatory nematodes due to the effect of organic amendments might have reduced the population of plant parasitic nematodes and increased plant growth.