Potential Use of Trichoderma sp. and Pseudomonas fluorescens to Control Phytophthora capsici in vitro and Promoting the Growth of Black Pepper (Piper nigrum L.) in the Nursery

Abstract

Biocontrol agents, Trichoderma sp. and Pseudomonas fluorescens isolated from black pepper rhizosphere soil were identified by microscopic and macroscopic features along with the emission of green fluorescence under ultra violet radiation. Trichoderma sp. was mass multiplied in tea refuse. Higher number of colony counts were recorded when P. fluorescens grown in sorghum (Sorghum bicolor L.) and rice (Oriza sativa L.) substrates. As the both biocontrol agents showed antagonistic ability over Phytophthora capsici under in vitro condition, showing significantly higher level of growth inhibition, a nursery experiment was conducted using six different combinations of treatments to find out in vivo biocontrol ability. Treatments applied were Trichoderma sp. treated plants, P. fluorescens treated plants, both Trichoderma sp. and P. fluorescens treated plants, un inoculated tea refuse applied plants, un inoculated sorghum seeds applied plants and normal potting mixture with no substrate. Treated plants showed greatest mean plant height than untreated control (P< 0.05), The highest leaf area of 125.37cm 2 was recorded in P. fluorescens treated plants while the lowest value of 89.8 cm2 was in untreated control. The highest root volume was recorded in Trichoderma sp. and P. fluorescens treated plants. Root volume, root dry weight and plants' survival % in treated plants were significantly (P< 0.05) higher than the control. Shoot dry weight was significantly (P< 0.05) high in P. fluorescens treated plants. The results indicate that Trichoderma sp. and P. fluorescens enhanced plant survival rate and growth that could serve as bio control agents and growth promoters.