Effects of Trichoderma asperellum on nutrient uptake and Fusarium wilt of tomato

Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici (FOL), results in severe losses in tomato production. Biological control offers a promising alternative to manage this disease due to its eco-friendly nature compared to pesticides. The objectives of this study were to select a species' strain of Trichoderma for containerized-transplant production to reduce Fusarium wilt and to determine the relationship between disease severity and nutrient uptake of tomato plants. Fifty eight isolates of Trichoderma were obtained from field soils and commercial composts. Of these 58 isolates, isolate CHF 78 showed the best antagonistic ability against FOL in a dual culture test and was further studied. The taxonomy status of CHF 78 was determined using combined sequences of internal transcribed spacer (ITS) and translation elongation factor-1α gene (TEF1α). The plant growth promoting traits and biocontrol efficiency of CHF 78 were also evaluated. Phylogenetic analyses demonstrated that CHF 78 was T. asperellum. This strain also showed several plant growth-promoting traits including the ability to solubilize Ca3(PO4)2, and to produce cellulases, chitinases, indole acetic acid (IAA), proteases, and siderophores. In addition, CHF 78 significantly increased dry weight and plant height of tomato plants inoculated with or without FOL compared to those inoculated only with FOL. Inoculation of tomato plants with CHF 78 significantly reduced disease severity of Fusarium wilt, and pre-inoculation of tomato plants with CHF 78 followed by inoculation with FOL significantly promoted nutrient uptake of P, K, Mg and Zn as a result of reducing disease severity and these plant growth promoting traits. Interestingly, there was a significantly negative correlation between disease severity and nutrient uptake of all the elements analyzed in this study. Trichoderma asperellum strain CHF 78 can potentially be used to reduce Fusarium wilt and promote plant growth and nutrient uptake under commercial tomato production.