Consórcio de Azospirillum, Bacillus e Acaulospora na atividade microbiana do solo e no crescimento de genótipos de milho crioulo, varietal e híbrido

Abstract

In Brazil, corn is considered a strategic crop and ranks second among the most cultivated, soybeans being the first. The use of inoculants with plant growth-promoting microorganisms also proved to be a technology to reduce chemical inputs. This study aimed to evaluate inoculation effect with rhizobacteria and arbuscular mycorrhizal fungi (AMF) on initial growth and microbial activity in maize genotypes. The experiment was conducted in a greenhouse with 16 treatments with 4 repetitions and one positive control. The evaluated factors were four maize genotypes:Crioule 1 and 2, rustic (Eldorado), and hybrid (MG711) combined with inoculation levels without inoculation (WI), arbuscular mycorrhizal fungus A. morrowiae UFLA-226 (AMF), rhizobacteriaAzospirillum sp.-BR 13925, Azospirillum sp.-BR 13796, and Bacillus sp.-BR 15130 (BACT), arbuscular mycorrhizal fungus and rhizobacteria (AMF-BACT). After 50 days of conducting the experiment, chlorophyll content, aerial and root dry mass, basal respiration, carbon and nitrogen microbial biomass, acid phosphatase, fluorescein diacetate hydrolysis, β-glycosidase, P accumulation, N and P concentration of soil, colonization and spores density were evaluated.In terms of plant development, the hybrid MG711 increased shoot dry matter (SDM) with combined or separate inoculations. In Crioula 1 had the highest phosphorus (P) accumulation in the plant with combination. In terms of colonization and microbial activity, MG711 had the highest values in basal soil respiration with AMF-BACT,in microbial quotient (qCO2) of Crioula 1 with BACT showed greater efficiency. The results indicate that the responses to combined AMF-BACT inoculations are highly dependent on the maize variety. The hybrid MG711 showed a positive response in plant development and slight promotion in microbial activity, followed by traditional genotypes.