Lower growth rate of the açaí palm seedlings limits the crops' commercial expansion. The goal was evaluating the biometry, biomass accumulation, nutrient contents, chlorophyll-a fluorescence, and gas exchange in açaí seedlings inoculated with rhizobacteria. The treatments were individual inoculations of the seven rhizobacteria isolates and one control (without inoculation) on the roots. Biometry and biomass data were submitted to cluster analysis to separate the isolates into groups according to the similarity degree, and groups' means were compared through the SNK test. Three groups were formed; group 1 was composed of the control; group 2 of the UFRA-35, UFRA-38, UFRA-58, UFRA-61, UFRA-92, and BRM-32111 isolates; and group 3 was composed of the BRM-32113 isolate. Group 2 and 3 isolates promoted an increase in growth, biomass accumulation, higher levels of nutrients and chlorophyll, and improvements in the gas exchange and chlorophyll-a fluorescence in comparison with the control. The results evidenced that the rhizobacteria accelerate the growth, increase the photosynthetic efficiency, and induce the leaf nutrient accumulation in açaí palm seedlings. The rhizobacteria inoculation can contribute to the sustainable management of the açaí palm seedling production in nurseries.
Keywords: Biofertilizer; Biostimulants; Euterpe oleracea; Photosynthesis.