Natural occurrence of Azospirillum brasilense in petunia with capacity to improve plant growth and flowering

TOFFOLI, LUCÍA MERCEDES; FONTANA, CECILIA ALEJANDRA; ELÍAS, JULIANA M.; MARTÍNEZ ZAMORA M.G.; LOVAISA NADIA C.; SALAZAR SERGIO M.; NORMA MEDRANO; DELAPORTE QUINTANA PAOLA; PEDRAZA RAÚL O.

JOURNAL OF BASIC MICROBIOLOGY

WILEY-V C H VERLAG GMBH

Año: 2021

0233-111X

To evaluate the natural occurrence of the plant growth‐promoting bacteriumAzospirillum brasilense and petunia plants, local strains were isolated andcharacterized by biochemical and molecular methods. Three strains were assessedin greenhouse conditions using Petunia × hybrida Ultra?. Treatments:Plants without bacterial inoculation or chemical fertilization; fertilized withNPK and KNO3; and independently inoculated with the strains 2A1, 2A2, and2E1 by submerging their roots in a bacterial suspension (~106 CFU·ml−1). Rootlength, dry weight of roots and shoots, leaf area, leaf greenness, and nutrientcontent were evaluated. The number of days from transplanting to the openingof the first flower and the number of flowers per plant were also determined.As a result, five isolates were characterized as A. brasilense, showing thecapacity to produce indoles and siderophores, to solubilize phosphate, nitrogenaseactivity, and nifH‐PCR amplification. In general, all the parametersof the plant assay were improved in plants inoculated with A. brasilense, withvariations among the strains, as well as the onset of flowering and the numberof flowers per plant, compared with uninoculated or fertilized plants. This isthe first report on the natural occurrence of A. brasilense in petunia with thecapacity to improve plant growth and flowering.