Beneficial microorganisms are important for survival and development of micropropagated plants. The objective of this work was to evaluate the potential of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR), isolated and/or combined (in dual inoculation) on acclimatization of Zingiber spectabile Griff. The experiment was carried out in a greenhouse using containers of 300 mL and dust from coconut shell (Amafibra®) as substrate. The experimental design was completely randomized with two AMF treatments [Glomus etunicatum (Ge) and the mixture of G. etunicatum and Gigaspora margarita (Ge/Gm)], two treatments with PGPR inoculation [Bacillus thuringiensis (HPF14) and B. pumilus (HPS6)], four treatments combining these microorganisms [Ge+HPS6, Ge+HPF14, Ge/Gm+HPS6 and Ge/Gm+HPF14] and a control treatment (not inoculated), with eight replicates. After 90 days survival percentage, height, leaf area, fresh and dry biomass of shoots (FBS and DBS) and roots (FBR and DBR), mycorrhizal colonization and content of macro and micronutrients in the shoot were evaluated. Co-inoculation (Ge/Gm+HPS6) benefited significantly the mycorrhization when compared to the other treatments, resulting in higher FBS than that produced by HPF14 inoculation. Although with 100% survival after the acclimatization period, the development of Z. spectabile inoculated with HPF14 isolated and/or combined with AMF is lower than the observed for control plants. The results suggest that the use of plant growth-promoting microorganisms should be done carefully, considering the cost/benefit of the application.
Glomeromycota; rhizobacteria; Bacillus sp.; micropropagation; ornamental plants
