Desenvolvimento de biofertilizante contendo o fungo solubilizador de fosfato Aspergillus niger

Abstract

Phosphate fertilization is one of the main components to achieve high crop yields, since phosphorus (P) is a limiting element in most soils. On the other hand, the production of fertilizers used to overcome this limitation is based on nonrenewable sources. Thus, microorganisms able to solubilize P from sparingly-soluble minerals are a promising alternative for the management of phosphate fertilization. One of the bottlenecks to apply these microorganisms is the development of inoculants that guarantee the arrival and permanence of the organism in the target. The present work had as objective to develop a formulation of biofertilizer containing the phosphate-solubilizing fungus Aspergillus niger. The shelf life of the formulation was evaluated monthly in two temperature conditions: environment and refrigerator, in order to verify the germination capacity of the fungus over time. The formulation was evaluated in vitro to characterize its capacity to solubilize calcium phosphate in the presence and absence of sucrose, and under field conditions as an inoculant in the production of coffee seedlings. The formulation was inoculated 2 cm below the seeds and the development of the seedlings was monitored monthly, using as reference plant growth variables: height, stem diameter, number of leaves, root volume, shoot and root dry mass and chlorophyll. The results obtained for the shelf life showed that the formulation remained viable until the sixth month of evaluation, germinating 100% of the granules and counting 1.1 x 105 UFC g-1. As to the capacity to solubilize calcium phosphate, the formulation produced a P-solubilization halo 292% higher in the presence of sucrose. In the soil-plant experiment, inoculated seedlings showed, height of 5.6%, stem diameter of 6.1%, and a number of leaves of 8.5% higher to the non-inoculated ones, besides a greater development of root system.