Estudo da mobilidade do Azospirillum brasiliense em gramíneas sob diferentes formas de inoculação

Abstract

Inoculation of Azospirillum brasilense in maize has become a standard practice among Latin American farmers, providing greater productivity, efficiency in the use of water and nutrients and resistance to environmental stresses. Members of the genus Azospirillum can be free-living, rhizospheric, epiphytic or facultative endophytes. Knowing the level of association between the plant and the bacterium is important for choosing the appropriate inoculation method. Therefore, the objective of the project was to monitor the colonization of three A. brasilense strains (Ab-V5, Az39 and HM053) inoculated by three inoculation methods (seed, foliar and soil) in maize plants. For this, maize plants were grown in a greenhouse for 42 days. Throughout the experiment, A. brasilense populations in the roots and shoots were accessed by qPCR ranging from 103 to 107 CFU plant-1, depending on the inoculation method and the maize development stage. The Ab-V5 and HM053 strains showed to efficiently colonize the rhizosphere and roots, showing no mobility through the plant. On the other hand, Az39 showed systemic behavior, being able to translocate from roots to shoots and vice versa. The inoculation of Ab-V5 and Az39 presented the best results in terms of growth promotion when inoculated via soil, while for HM053 inoculation via seeds got better results than the other methods.