Biological effect of nanoparticles loaded with microbial indoleacetic acid on tomato morphometric parameters

The tomato is one of the vegetables that have the highest production worldwide, so for its fertilization and pest control products of synthetic origin are used, which affect the ecosystem where they are applied, for this reason biologically sustainable alternatives are sought. One of these alternatives is the use of microbial metabolism, an example of this is Botryodiplodia theobromae, a phytopathogenic fungus capable of producing phytohormones from its metabolism, such as indolacetic acid (IAA). However, exogenous application of this phytohormone exhibits accelerated degradation when in contact with environmental factors. An alternative to minimize this effect is encapsulation with the use of biopolymeric materials that have the ability to coat the phytohormone and at the same time allow to increase the effectiveness of the product. In this work, the encapsulation efficiency (EE) of IAA from microbial broth was evaluated by liquid fermentation of B. theobromae in alginate/chitosan nanoparticles (Np) (ALG/QS); as well as its biological effectiveness represented in morphological development patterns in tomato plants. The results showed that IAA was produced from the microbial metabolism of Botryodiplodia theobromae, which once encapsulated reached an EE of 90%, as well as various particle sizes. Regarding the biological effectiveness in tomato plants, it was observed that the Np loaded with microbial broth and synthetic grade IAA showed a significant difference in most of the morphological parameters evaluated compared to the absolute control. Therefore, nanosystems loaded with biostimulants are shown as a future alternative for the application of biostimulants in vegetables such as tomatoes.