BIOFILM BASED CONSORTIA FOR GROWTH PROMOTION AND SOIL-BORNE DISEASE MANAGEMENT IN COWPEA (VIGNA UNGUICULATA L. WALP)

Abstract

Biofilm based antagonists were evaluated for growth promotion and soil borne disease management in cowpea (Vigna unguiculata L. Walp). Nine Trichoderma sp. and five Bacillus sp. were obtained from ten rhizosphere soils of cowpea growing areas of Thrissur district (Kerala). The highest population of Trichoderma sp. was recorded in Chellakara (4.8 x 103 cfu g1) and Bacillus sp. in Pananchery (4.48 x 103 cfu g ́1). Among Trichoderma sp., TCH (Chellakara) isolate recorded maximum inhibition (51,1 %) against Rhizoctonia solani and Pythium aphanidermatum (57.7 %). None of the Bacillus sp. showed antagonistic activity against Rhizoctonia solani and Pythium aphanidermatum. Bacillus sp. were screened for biofilm production, and BCH (Chellakara) isolate (0.0600) was the most efficient followed by BPN (Pananchery)(0.058) and BML (Mala) (0.056). Based on the plant growth promoting traits and antagonistic activities, three most efficient Trichoderma sp. (TCH, TPZ and TMT) and Bacillus sp. (BCH, BPN and BML) were selected for further studies. Three best Trichoderma based Bacillus sp. biofilms (TPZ+BPN, TCH+BCH and TMT+BML) were selected based on the growth promotion, antagonistic activity, biofilm production and compatibility under in vitro. Population of inoculated Trichoderma sp., Bacillus sp. and Rhizobium sp. in the potting mixture showed declining trend till the final harvest of the crop. Among the biofilm based formulations, TCH (Trichoderma sp.) + BCH (Bacillus sp.) (T2) was the most promising treatment for growth promotion and disease management in cowpea under pot culture studies. However, further studies are needed to evaluate under field conditions. Keywords: Biofilm, Cowpea, Trichoderma, Bacillus