POTENTIAL OF BACTERIA ASSOCIATED WITH MELIPONINI BEES ON THE GROWTH OF LETTUCE (Lactuca sativa L.)

Abstract

Facing the challenge for increasing food production, bacterial inoculants or biofertilizers emerge as sustainable biotechnological alternatives, which through diverse mechanisms like atmospheric nitrogen fixation (N₂), solubilization of nutrients such as phosphate, and secretion of hormones such as auxins, may promote plant growth. This study evaluated the ability of 16 bacteria associated with meliponini bees to promote growth in lettuce (Lactuca sativa L.). The ability to fix atmospheric nitrogen (N₂), solubilize phosphate and produce auxin was evaluated under in vitro conditions. Subsequently, the leaves and roots of lettuce seedlings were inoculated with the 16 strains. Data were subjected to a one-way analysis of variance and the mean comparison test (Tukey, ?= 0.05). Of the 16 strains, 87.2% showed efficiency for solubilizing phosphate; 81.2% for fixing N₂; and 50% for producing auxins. At 35 days after germination, the results indicated that leaf inoculation with Bacillus sonorensis significantly favored chlorophyll fluorescence and relative chlorophyll content, as well as seedling dry weight (aerial part and total). The root inoculation with Heyndrickxia acidicola significantly improved leaf area and dry weight of roots, aerial part and total. In conclusion, the bacteria B. sonorensis and H. acidicola have potential as plant growth promoters, and they represent a feasible option for the production of biofertilizers to promote the growth of vegetables such as lettuce.