Inoculation of Bacillus sp. improves root architecture, gas exchange and efficiency of nutrient use in Corymbia seedlings

• Bacillus sp. CCMD862 modified the root architecture of Corymbia . • Inoculation optimized chlorophyll a fluorescence. • Bacillus sp. CCMD862 generated nutrient use efficiency and biomass accumulation. • The morphophysiological changes contribute to the production of robust and more resistant seedlings. The inoculation of forest species with rhizobacteria growth promoters an increasing technology capable of improving the growth and also the final quality contributing to change robust and resistant originals. The objective was to evaluate growth, root architecture, gas exchange, chlorophyll a fluorescence, chlorophyll content and nutrient use efficiency in seedlings of Corymbia inoculated with the growth promoting rhizobacteria Bacillus sp. CCMD862. The growth promotion experiment was carried out in greenhouse, using hybrid clonal seedlings of Corymbia torelliana x Corymbia citriodora. The experimental design was CRD with 2 treatments (control and rhizobacteria Bacillus sp. CCMD862) with 5 replications for each treatment and 5 replicates per treatment (Bacillus sp. CCMD862 and Control - not inoculated). noculation promoted gains in gas exchange, chlorophyll fluorescence, nutrient use, biomass variables and in all root architecture parameters in relation to control. Biometric and biomass improvements resulted in higher DQI and a global growth promotion rate 30 % higher than control plants. The strain Bacillus sp. CCMD862 is able to biostimulate seedlings of Corymbia favoring the development of the root system, gains in the photosynthetic apparatus, increases in absorption and efficient use of nutrients that resulted in robust seedlings. The results obtained in this study must be confirmed in field conditions and the future development of an inoculant could assist with rooting in Corymbia, helping to reduce mortality in the field and obtain homogeneous commercial