Anais do Congresso Paranaense de Microbiologia
IV Congress of Microbiology in Paraná

Arbuscular mycorrhiza (MA) is a symbiotic association between plant roots and soil fungi presents, which enhances plant growth, due to increased water and nutrient absorption, mainly phosphorous, ensuring improved development and resistance to pests/ diseases. Mycorrhizal inoculants are an alternative to reduce the use of phosphate fertilizers, consequently reducing production costs and ambiental impact. The multiplication in association with roots transformed by the insertion of the Ti plasmid of Agrobacterium rhizogenes has already shown to be beneficial for obtaining a higher number of propagules, homogeneous batches, and contamination control. In this context, an inoculant based on multiplication of R. Clarus associated with tobacco roots transformed by the plasmid Ti of A. rhizogenes was evaluated and compared to current used systems, regarding colonization potential and productivity in soybean crop fields. The experiment was performed in the Bragança farm (countryside of Lucas do Rio Verde - MT, Brazil), starting on 07/11/2019 with harvesting on 02/05/2020 in soybean, cultivar RK8317 IPRO, in which nitrogen-fixing bacteria (BFN) were inoculated. For inoculation of the R. clarus in soybean seeds was used the substrate Mec Plant, according to the patent BR 102014017389. The experimental design was in randomized blocks, with four treatments and five replications: inoculum of R. clarus produced in vivo in vases in association with Urochloa decumbens (IS); inoculum of R. clarus multiplied in vitro in transformed carrot roots (IC); inoculum of R. clarus multiplied in vitro in transformed tobacco roots (IT); and control (C) (non-inoculated plants). The percentage of mycorrhizal colonization was evaluated by root collection and soybean yield. IT showed efficacy in increasing mycorrhizal colonization, reaching 89% of colonized roots, comparing to 62% of C. The other treatments also promoted higher colonization than the control, reaching 91% in IS and 79% in IC. In addition, the treatments IT, IS, and IC also showed gains in productivity of 16%, 19%, and 13%, respectively. These results illustrate the potential of the use of propagules obtained by cultivation in association with transformed tobacco roots as a base for agricultural inoculants in soybean crop.