The plant growth effect and biocontrol potential of Trichoderma sp. inoculation in tomatoes are dependent of the inoculation way

Tomato is an important economic crop due to its consumption and production worldwide. However, like other crops, it is susceptible to pathogens, being necessary agrochemicals to prevent diseases and improve the production of fruits. Among the sustainable alternatives to crop production, microbial inoculants are used as biofungicide and biostimulants for plant development. Thus, this work aimed to evaluate the biocontrol potential of seven Trichoderma spp. isolates (T1, T2, T3, T4, T15, T17, and T19) against tomato pathogens in vitro experiments, and their potential to improve tomato growth. The Trichoderma spp. antagonism was investigated against Alternaria sp. 003/09, Botrytis sp. 006/13, Fusarium sp. 007/09, and Stemphylium sp. A73. Dual culture, volatile, and diffusible compounds activity tests showed that all new Trichoderma spp. tested could reduce the mycelial growth of all tested pathogens, highlighting T15 and T17 isolates. Seed and soil inoculation revealed very contrasting results: Trichoderma sp. T17 showed a beneficial effect when inoculated in soil, reducing the percentage of yellowish leaves, and increasing dry weight and stem diameter. Inoculation of Trichoderma sp. T17 in the seed increases hypocotyl and radicle lengths, and the seed vigor index. Finally, the strains studied present the potential to be used to develop biocontrol products.