Do Azospirillum brasiliense and Chlorella sp. microalgae benefit the production of Hymenaea courbaril L. seedlings?

The use of Azospirillum brasiliense and Chlorella sp. has gained popularity in agriculture and forestry due to their benefits to plants. These two biological solutions have demonstrated potential to improve the performance and sustainability of crops and forest species, opening new perspectives for agriculture, and the recovery of degraded areas. Given the importance of establishing management strategies for seedling production and that information on forest essences is insufficient, the aim of this study was to evaluate the effect of intervals of Chlorella sp. microalgae application and inoculation with A. brasiliense doses on the growth and quality of Hymenaea courbaril L. seedlings. The experiment was conducted in a randomized block experimental design, and treatments were arranged in a 5 x 4 factorial scheme, with four replicates, testing five A. brasiliense doses: 0, 3, 6, 9, and 12mL/plant and four intervals of Chlorella sp. microalgae application: single application and every 7, 14, and 21 days after transplanting, for 120 days. Growth and photosynthetic parameters were evaluated. Inoculation with 6 and 9 mL of Azospirillum brasiliense, regardless of Chlorella sp. microalgae application favored the growth of H. courbaril seedlings. Chlorella sp. microalgae application at intervals of 14 and 21 days favored the responses of seedlings inoculated with A. brasilienses. The association between Azospirillum brasiliense and Chlorella sp. promoted gains in seedling production and quality.