Mycoparasitic Trichoderma viride as a biocontrol agent against Fusarium oxysporum f. sp. adzuki and Pythium arrhenomanes and as a growth promoter of soybean

Trichoderma viride was proved as an effective biocontrol agent against two fungal pathogens, Fusarium oxysporum f. sp. adzuki and Pythium arrhenomanes, infecting soybean. During an in vitro biocontrol test, Trichoderma showed mycoparasitism and destructive control against the tested fungal pathogens. Both the pathogens significantly influence the germination and P. arrhenomanes had a severe effect (only 5% germination). The root system of the soybean plant was poorly developed due to the infection and it exerted a negative influence on the nodulation and further growth phases of the plant. During pot assay along with biocontrol activity, Trichoderma showed growth promoting action on the soybean plant. Trichoderma enhanced growth of shoot and root systems and fruit yield after 12 weeks of growth. Pythium and Fusarium infected plants treated with Trichoderma had ∼194% and 141% more height than pathogens alone. The fruit yield treated with Trichoderma was ∼66 per plant whereas the yield was only 41 for a control plant. The plants infected with Pythium and Fusarium and treated with Trichoderma had fruit yields of 43 and 53 respectively and those were 5 and 1.6 times higher than plants infected with pathogens.

Research highlights
► The current study assures the efficiency of Trichoderma as biocontrol agents against fungal soil pathogens and indicates the need of production and development of Trichoderma based biocontrol agents to serve as a model for environment friendly biocontrol agent. The enhanced root system in soybean treated with Trichoderma directly enhanced the nodulation and more biological nitrogen fixation helps in the photosynthetic activity of plants. Thus the Trichodermal infection helps in the growth and yield of soybean providing its own metabolites and helps in the metabolism of nodulating bacteria. Trichoderma effectively controlled the pathogen and simultaneously increased the growth of plants and proved as avirulent opportunistic symbiont in rhizosphere of soybean plant. Antagonistic Trichoderma enhanced resistance against the secondary infection of pathogen in soybean.