A Novel Chitosan–Bentonite Nanoclay Bioformulation of <i>Trichoderma harzianum</i> as a Biofertilizer for Tomato Cultivation

The development of microbial inoculants represents a promising strategy for sustainable agriculture. In this study, we developed a solid formulation based on a chitosan-modified bentonite nanoclay (CHB) designed to carry conidia of Trichoderma harzianum . Compatibility of the T. harzianum IB-J15 strain with CHB was verified through in vitro assays, while scanning electron microscopy demonstrated the successful attachment of fungal conidia to the CHB surface. Remarkably, our findings revealed that CHB formulation maintained fungal viability after 3 months of storage at 4, 20, and 30 °C. Seed application of the formulated IB-J15 train on tomato plants resulted in an increase in root fresh and dry weight, as well as stem length. This study highlights the first use of a chitosan-modified bentonite nanoclay as a multifunctional carrier for Trichoderma conidia, providing an efficient platform for improved storage stability, handling, and plant-growth promotion in sustainable crop production.