Biocontrol of Root-Knot Nematode Meloidogyne incognita by Chitinolytic Trichoderma spp.

The inhibitory potential of chitinolytic Trichoderma spp. was assayed against Meloidogyne incognita in vitro and in vivo. Sixteen Trichoderma isolates were assayed for chitinase activity using basal solid medium supplemented with colloidal chitin. Isolates recorded high chitinolytic activity were identified morphologically as Trichoderma asperelloides, T. hamatum, T. harzianum and T. viride. The four species were quantitatively assayed for total and specific chitinase activity. T. asperelloides showed maximum chitinase activity (1.736 U/mL). In vitro studies revealed that egg hatching and second juveniles vitality of root-knot nematodes were significantly inhibited by chitinase-containing growth culture of the four selected chitinolytic Trichoderma species. However, the reduction effect was directly correlated with the concentration of fungal growth suspension. Under greenhouse conditions, three sequentially treatments of soil with homogenized culture suspension were studied. Trichoderma species significantly reduced the final nematode population by 97.81% and root galling by 92.81%. Moreover, all tested Trichoderma species obviously promoted tomato growth compared to untreated control. Significant positive correlation between the biocontrol efficacy of Trichoderma species against root-knot nematodes and their chitinolytic activity was confirmed. The most potential chitinolytic species, T. asperelloides, also recorded the highest biocontrol activity against M. incognita.