Azospirillum brasilense interaction effects with captan and thiodicarb on the initial growth of corn plants

The application of biological products containing diazotrophic bacteria in the seed has been highlighted as an alternative to reduce the use of nitrogen fertilizers; however, the chemical treatment of the seeds may negatively affect the survival rate of these microorganisms in the soil. The effects of the application of captan (fungicide) and thiodicarb (insecticide) in association with the inoculation of Azospirillum brasilense were investigated in this study for the corn crop. The research was conducted under greenhouse conditions at Universidade Estadual do Centro-Oeste (UNICENTRO), in Guarapuava, Parana, Brazil, and under laboratory conditions at the Universidade Federal da Fronteira Sul (UFFS), in Laranjeiras do Sul, Parana, Brazil. A completely randomized experimental design with eight treatments and four replicates was used. The treatments were as follows: control; A. brasilense; captan; thiodicarb; captan + thiodicarb; A. brasilense + captan; A. brasilense + thiodicarb; A. brasilense + captan + thiodicarb. The germination and seedling growth rates were evaluated in the laboratory. In the greenhouse were measured the growth of the roots and shoots until the V8 corn growth stages. The use of A. brasilense alone resulted in higher plant growth when compared to the control treatment, whereas the association of A. brasilense with captan and thiodicarb resulted in a similar response to the uninoculated and control treatments. These results suggest that there was a possible toxic effect of seed treatment with these products. The use of captan and thiodicarb interfere in the interaction of diazotrophic bacteria with root growth, affecting the germination rate and initial corn growth.