Functional microbiome of Ananas spp. as growth-promoting agent in pineapple BRS Imperial

The pineapple cv. BRS Imperial developed by Embrapa Mandioca e Fruticultura has excellent agronomical and sensorial attributes with great market acceptance. However, the cultivation of plants is time-consuming with low performance and slow growth, limiting adoption especially by large-scale pineapple growers. Therefore, the aim of this study was to evaluate the growth potential of bacteria from the associated microbiome of Ananas spp. in order to validate its application in different stages of cultivation (semi-field, in vitro and greenhouse), for the production of seedlings on a large scale. Eighteen treatments consisting each of a different bacteria from the biological collection of microorganisms associated with the Ananas genus, were tested under semi-field condi-tions. Three treatments (BAC25, BAC222 and BAC406) were selected to validate the microbiolization process of pineapple seedlings from the cv. BRS Imperial in vitro (rooting stage) and in vivo (acclimatization in the greenhouse) together with a mixed treatment (composed by the combination of the three bacteria) and a control treatment (untreated plants). The in vitro cultivation was carried out in commercial substrate autoclaved with MS nutrient medium where bacterial suspensions were added according to the treatments mentioned above. Each treatment consisted of 120 replicates, totaling 600 experimental units. The evaluations were carried out at weekly intervals for a period of 42 days, when destructive analyses were performed. The remaining plants were transferred to the greenhouse and evaluated from this stage until complete acclimatization. For the in vivo validation, the bacterial suspensions were applied to the substrates contained in plastic cups, with pineapple seedlings of the cv. 'BRS Imperial', totaling 200 plants per treatment. The evaluations consisted of measuring growth variables and destructive analysis. The data obtained were subjected to analysis of variance and the means grouped by the Scott-Knott test at 5% probability. The BAC25, BAC222 and BAC406 treatments promoted plant growth and biomass increment in semi-field conditions. BAC406 was the most promising in promoting growth of pineapple seedlings in vitro, while BAC222 was the best treatment for the in vivo cultivation. The results obtained demonstrate that the bacteria tested have great potential for use in the different stages of cultivation of micropropagated seedlings, improving growth, health and vigor of plants.