Efficacy of Trichoderma asperellum against Ralstonia solanacearum under greenhouse conditions

Abstract

The rhizosphere soil samples of healthy tomato plants were used to isolate Trichoderma spp and identified based on morphological and molecular characterization as a Trichoderma koningii (T1) T.  flavofuscum (T2), T. harzianum (T3), T. asperellum (T4), T. harzianum (T5 & T7), T. koningii (T6), T. asperellum (T8), T. harzianum (T9), T. viride (T10). The isolates screened for antagonistic activity against ten virulent strains of Ralstonia solanacearum (Rs). Two isolates of Trichoderma (T4 and T8) exhibiting high antagonistic activity (24-29mm and 20-27mm respectively) and also studied for several biocontrol mechanisms under greenhouse conditions. These strains were found to be positive to protease, β-1, 3-glucanase, Cellulase, Chitinase, Xylanase, Amylase, Pectinase and lipase activity.  Germination percentage increased by 48% and 45% by Trichoderma with pathogen treated seeds and also increased root length, shoot length, fresh weight, dry weight and vigour index. Efficacy of T4 and T8 isolate were evaluated under green house conditions in suppressing disease and promoting tomato plant growth. The disease incidence was significantly reduced by about 50% in tomato plants raised under green house conditions.