Triagem do potencial de promoção do crescimento vegetal de rizobactérias isoladas de alface

Abstract

Terrestrial plants are colonized by a large number of microorganisms. Rhizopheric microorganisms, which colonize root adjacencies, provide a large amount of nutrients through the decomposition of organic matter and nutrient cycling, as well as improving root architecture and protecting the host against phytopathogens. Thus, the objective of this work was to screen bacteria isolated from lettuce rhizosphere, Lactuca sativa, with the best capacity to promote plant growth. For this purpose, 6 strains were selected from the bacterioteca and triaged for idol-acetic acid (AIA) production, phosphate solubilization, nitrogen fixation, enzyme production, cellulases and chitinases, biofilm formation and, finally, root colonization. All isolates were capable of producing at least one characteristic analyzed, as well as they were able to produce biofilm. The isolated AG4 has obtained the highest phosphate solubilization index, the isolated AG7 has produced the highest number of plant growth factors. With the exception of AG1, all others were able to colonize lettuce roots. Thus, the isolates Enterobacter cloacae (AG3), Enterobacter cancerogenus (AG5), and Enterobacter ludwigii (AG7) are good candidates for inoculants, because beyond their capacity of colonize the host roots, they are produce a high number of plant growth promoters.