In vivo interaction in antagonistic potential of Trichoderma spp. and Pseudomonas fluorescens

Studies were carried out to find out interaction between antagonism activity of Pseudomonas fluorescens on the different species of Trichoderma. The inhibition in growth of Trichoderma was 8.59% when Trichoderma was used first and 59.44% when P. fluorescens was used first in a dual culture test. Highest growth inhibition (59.44%) of Trichoderma (Th3) was recorded when P. fluorescens was first inoculated in King's medium B agar (KMB) 24h prior to inoculation of T. harzianum. The lowest inhibition (8.59%) was recorded in T. viride (Tv1) when the isolate was inoculated in KMB prior to inoculation of P. fluorescens. All other isolates of Trichoderma, irrespective of the species, exhibited intermediate growth inhibition ranging from 9.87% in potato dextrose agar (PDA) (Tv1) to 59.18% in KMB (Th3). When the cell-free culture filtrate (5%) of P. fluorescens was used against different species and isolates of Trichoderma, it also caused growth inhibition of fungal antagonist to different levels (5.55 for Tvs1 to 25.92% for Th3). In steamed soil, recoverable number of Trichoderma population gradually increased (90 x 10⁵ CFU g⁻¹ of soil for Th3 to 172 x 10⁵ CFU g⁻¹ of soil for Tvs1) irrespective of the species over a period of 14 days incubation.