Bio-efficacy of Trichoderma-fortified compost in controlling onion diseases and improving yield of onion (Allium cepa L.)

摘要

In recent years, the genus Trichoderma has achieved a special position in the field of agriculture as a potent fungal bio-agent besides being a plant growth promoter and improving composting ability. They are enormously interactive in root, soil and foliar environments and economically viable for combating a wide range of plant diseases. In this study, an attempt was made to control seedling mortality, damping off diseases of onion at different growth stages caused by several fungal pathogens using Trichoderma-fortified compost mixed with different substrates including saw dust, cowdung, tea waste, water hyacinth and poultry refuges. Pathogens included Alternaria porri, Fusarium oxysporum, Rhizoctonia solani, and Sclerotium rolfsii in onion field under natural epiphytotic conditions. Additionally we also observed the effect of Trichoderma-fortified composts on growth promotion components and yield of onion. Among the 20 isolates screened in dual culture assay on PDA, T. harzianum isolate Pb-9 was found to show the highest radial growth inhibition of Alternaria porri, Fusarium oxysporum, Rhizoctonia solani, and Sclerotium rolfsii. Trichoderma-fortified compost with poultry manure was found most effective in reducing seedling mortality, damping off, incidence and severity of foliar and soil-borne diseases in onion field. The lowest disease incidence and severity were observed with spraying spore suspension of T. harzianum Pb-9 on leaf in controlling purple leaf blight disease of onion caused by A. porri. All the treatments significantly increased the growth promoting components and yield where the highest increased was achieved with the treatment Trichoderma-fortified poultry manure compost.