NEMATICIDAL POTENTIAL OF CULTURE FILTRATES OF SOIL FUNGI ASSOCIATED WITH RHIZOSPHERE AND RHIZOPLANE OF CULTIVATED AND WILD PLANTS

Abstract

Several fungi are known to regulate the nematode densities in soil by exhibiting a range of antagonistic activity including production of nematoxic compounds. Since fungi and nematodes occur together in the rhizosphere, the toxic metabolites naturally produced by fungi may be responsible for keeping a low level of nematode populations. In this study culture filtrates of several isolates of fungi, isolated from rhizosphere and rhizoplane of cultivated and wild plants exhibited significant nematicidal activity on Meloidogyne javanica, by killing 2nd stage juveniles at varying degrees. Aspergillus candidus, A. fumigatus, A. niger, A. ochraceus, A. sulphureus, A. terreus, A. ustus, Cephalosporium sp., Chaetomium flavum, C. globosum, Cladosporium sp., Memnoniella echinata, Paecilomyces lilacinus, Penicillium aspermum, P. citrinum, P. purpurogenum, P. raistrickii, Scopulariopsis brumptti, Stachybotrys atra, S. parvispora, Trichoderma hamatum, T. harzianum, T. koningii, T. viride and Verticillium chlamydosporium (Pochonia chlamydosporia) showed highest nematicidal activity. However, different isolates of same species of fungi showed variation in their nematicidal potential. Secondary metabolites from fungi associated with rhizopshpere and rhizoplane of crop plants offer an exciting area of research for the discovery of potential nematicidal compounds.