Impact assessment of Karanja deoiled cake and sundried biogas slurry as a mixed substrate on the nematicidal potential of Purpureocillium lilacinum

Abstract

The present study explored the feasibility of waste biomass viz., Karanja (Pongamia pinnata) deoiled cake (KDC), and sundried biogas slurry (BGS) as a mixed substrate to develop Purpureocillium lilacinum 6029 based fungal formulation against plant-parasitic nematode, Meloidogyne incognita. The fungus cultured on KDC-BGS in a 60/40 ratio showed maximum egg mass inhibition (96.8%) and protease activity (376.65 U/g) along with superior colonization ability (100% colonization of egg mass on the third day). Incidentally, P. lilacinum spores obtained from the traditional substrate (wheat) inhibited only 68.72% egg mass hatching with a comparatively poor colonization rate construing the linkage between the nature of substrate and virulence of the fungus. Bioefficacy studies on tomato plants in the greenhouse revealed that the formulation with KDC-BGS as a substrate was 1.19 times more effective than the wheat-based formulation in controlling nematodes. Enhanced physical-biochemical parameters of tomato plants treated with the bioformulation further substantiated KDC-BGS as a reliable and economical substrate for P. lilacinum.