Currently, Eucalyptus spp. is the tree that is most widely planted in Brazil, occupying 81.6% of planted forests. In 2009 its productivity was 44.2 m³ of eucalyptus with bark/hectare, generating about 46,850 direct jobs. Studies of beneficial bacteria, such as plant growth-promoting rhizobacteria (PGPRs), have been carried out for more than a century. The objective of this work was to evaluated strains of facultative extremophile bacteria that show potential in promoting eucalyptus growth. Seeds from the hybrid "urograndis" were microbiolized with a suspension of 10(9) UFC/mL from 10 bacterial strains, by means of shaking at 150 rpm in a rotating incubator, at 28 ºC for 24 h. Next, they were planted in seed-trays and kept in the greenhouse. After 60 days seed germination and dry weight of the aerial part and roots were evaluated.. The dry weight of the aerial part revealed that all the bacterial strains produced gains when compared to the control, varying from 11.3 to 78.0%. However, strains UnB 1366, UnB 1371, UnB 1375, UnB 1370 and UnB 1373 were the ones that differed significantly. In contrast, the UnB 1368 strain (Bacillus sp.) stood out individually in promoting an increase of 130.0% in root biomass. These strains should be more thoroughly studied with regard to vehicle, combinations, formulations and others, so that they may be used in optimizing seedling production.
Root biomass,Seed microbiolization; Seedling production
