The Effect of Compost and Biochar Amendments, as Well as the Inoculation of Arbuscular Mycorrhizal Fungi and <i>Trichoderma harzianum</i> , on the Control of <i>Fusarium oxysporum</i> Pathogen on Tomato ( <i>Solanum lycopersicum</i> L.) in the Greenh

In Ethiopia, one of the most extensively grown vegetable crops is the tomato ( Solanum lycopersicum ). Its fruits are eaten in a variety of ways and are high in vitamins. However, because of pests and illnesses, tomato yields in smallholder cropping systems fall short of the crop’s potential. Thus, the goal of this study is to investigate how tomato biomass, fruit yield, and the management of the tomato wilt pathogen Fusarium oxysporum f. sp . lycopersici are affected by the inoculation of arbuscular mycorrhizal fungi (AMF) and Trichoderma harzianum , as well as compost and biochar amendments, in the greenhouse at Hawassa University. Sterilized soils were used to grow the plants in plastic containers. The control was one of fourteen treatments. Growth measurements and disease evaluation were performed for certain parameters after 15, 30, and 45 days of growth using a completely randomized method. With the exception of the F. oxysporum f. sp. lycopersici inoculation, all treatments significantly ( p &lt; 0.05) increased height, leaf area, stem diameter, and shoot and root wet and dry biomass output. During the early days of growth for treatments AMF + Fusarium and AMF + Trichoderma was recorded the highest height, leaf area, and stem collar diameter for Galilea variety and variable values for Roma V.F.N variety. When compared to plants treated with F. oxysporum pathogen alone and control, improvement in the various growth parameters was recorded in the plants treated with AMF, T. harzianum , biochar, and compost sole and combined. Better fruit yield and pathogen resistance were recorded for Roma variety. In addition to growth parameters, all AMF inoculated treatments demonstrated root colonization and sporulation. Nutrient uptake was enhanced in all treatments except for sole Fusarium and control treatments. Mycorrhizal dependency was better for sole AMF inoculation treatment in both varieties. Disease severity was lower in Roma variety while Galilea variety was found to be more susceptible to Fusarium pathogen. Accordingly, significant fruit loss was recorded for Galilea variety. In conclusion, AMF and Trichoderma inoculation and application of biochar and compost have improved performance of the two tomato varieties. In addition, it was recorded that Roma variety is much more resistant to Fusarium pathogen as it is inoculated with the two bioinoculants, which indicates that different varieties show different resistance to Fusarium pathogen. Therefore, when growing tomato, it is recommended to select the appropriate biopesticides like that of AMF and T. harzianum and appropriate variety of tomatoes. Finally, as this study focused on only two tomato varieties and two bioinoculants, wide coverage of other bacterial and fungal inoculant production and application in the smallholder farms is also recommended.