Nematode Extract-Induced Resistance in Cowpea against M.Incognita

Abstract

Every plant in the world has a special defence mechanism to protect themselves from their enemies. In India, total crop losses annually 10-40% by plant-parasitic nematodes. These plant parasitic nematodes are roundworms, which are microscopic in nature. Although there are hundred different kinds of plant parasitic nematodes infect plants, root-knot nematode (Meloidogyne incognita) is one of the serious pest for cowpea plants. They manage to evolve sophisticated defence mechanism for their own protection and also creates interrelationship with the roots of their host plant to form giant cells. They also have the capacity to sense and respond to chemical signals of host plant and by this way they orient themselves within the roots and enhances own survival. Present investigation was carried out to establish the biocontrol potentiality of nematode extract (Meloidogyne sp.) on Vigna unguiculata (cowpea) L.walp variety infected with Meloidogyne incognita (Kofoid& White) Chitwood nematode. The result of in vitro laboratory bioassay showed that application of nematode extract safe for second- stage juveniles (J2) of M. incognita. The result of in vivo test revealed that nematode extract increased growth of inoculated plants in terms of shoot length, shoot weight and root length as compared with inoculated untreated plants. Application of nematode extract showed reduction in root gall number and number of nematode eggs in inoculated roots. In nematode extract treated plants PAL (Phenylalanine ammonia lyase) activity generally increased in the roots which may interfere with infected juveniles at the time of root penetration. Although there are several current management practices have been identified for plant nematode control such as use of botanicles, cultural practices, physical methods, chemical nematicides etc but application of nematode extract is one of new method which ultimately reduces management cost and enhances crop production.