Evaluación de la capacidad de solubilización de fosfatos por bacterias asociadas a la rizosfera de papa Solanum tuberosum L. Var. Superchola

Abstract

The objectives of this research were to evaluate, select, characterize and conserve the bacterial isolates associated with the potato rhizosphere with the highest phosphate solubilization capacity from four potato-producing localities in the province of Tungurahua, starting with the planting of potato tubers of the Superchola variety in 6 L pots, which after 45 days from sprouting, the bacteria that presented phosphate solubilization halos were isolated, for which the Pikovskaya Agar culture medium was prepared. A completely randomized design was used, the bacterial isolates from the locality with the highest average ranges were from the locality of Pinguilí in the Mocha canton. Of the 40 bacterial isolates, the one with the lowest capacity to solubilize phosphates was isolate CC-FCAGP-BSF10, although it had no significant statistical difference with respect to isolates CC-FCAGP-BSF12, CC-FCAGP-BSF19, CC-FCAGP-BSF13, CC-FCAGP-BSF15, CC-FCAGPBSF14 and CC-FCAGP-BSF31. Of the 40 culturally characterized isolates, 28 % were dominated by umbelliform elevation, 62 % by circular colony forms, 85 % by entire edges, 92 % by shiny, 92 % by smooth texture and 80 % by colonies of smooth consistency. In morphology, bacilli predominated with 50 %, in grouping, diplobacilli predominated with 45 %, and in Gram reaction, Gram (-) bacteria predominated with 83 %. For the quantification of bacteria per gram of soil of each locality, serial dissolutions were made after 48 hours of incubation at 28ºC, proceeding to the count of CFU.g per soil of each locality, giving as a result that the locality of Santa Rita del Cantón Píllaro was the one that reached the highest average range. For the preservation of the bacterial isolates with the highest phosphate solubilization capacity, 1.5 ml eppendorf tubes were used with two variants: 25% glycerol or 20% glycerol plus brain heart infusion culture medium (BHI). According to the results obtained, the isolates with the highest phosphate solubilization capacity were found in the locality of Pinguilí in Mocha county, which are promising candidates for biofertilizers, while the isolates with the lowest solubilization capacity were found in the locality of El Placer in Quero county, which at the same time was the locality with the lowest number of bacteria per gram of soil, demonstrating the reduced bacterial biodiversity of this locality.