Eficiência das estirpes Azospirillum brasilense Ab-V5 e HM053 no desenvolvimento e produção de morango (Fragaria x ananassa, Duch. cv. Florida Festival)

Abstract

Plant Growth Promoting Rhizobacteria (PGPR) stand out due to their ability to stimulate plant growth through biological nitrogen fixation, production of phytohormones, protection against pathogens, mineral solubilization, among others. Strawberries are small fruits of high commercial value, globally appreciated for their organoleptic and nutraceutical characteristics, however, their production is intensive and requires high inputs of nitrogen fertilizers and pesticides. The genus Azospirillum is one of the most promising PGPR, but its use associated with different doses of nitrogen is still poorly explored in strawberry cultivation under field conditions. To understand the effect of Azospirillum as a biofertilizer in strawberry cultivation, two experiments were conducted using Azospirillum brasilense strains Ab-V5 and HM053, associated with different doses of nitrogen. Experiment I was conducted in a completely randomized design, while Experiment II was conducted in completely randomized blocks, both in a triple factorial (3x4x2), in a greenhouse and in the field, respectively, where the two strains were associated with doses of 0, 25% (185 mg), 50% (370 mg), and 100% (740 mg) of nitrogen and inoculated by foliar spraying or in the soil, near the roots. In both experiments, the growth characteristics of the strawberry plants, fruit production, and quality were evaluated. In the greenhouse experiment, it was observed that the strawberry plants showed favorable responses when inoculated with A. brasilense HM053 or Ab-V5. The association of HM053 with 25% or 50% nitrogen provided the best growth parameters. Based on the results obtained in Experiment II, it was observed that the strawberry plants responded positively to inoculation with A. brasilense Ab-V5 and HM053. The best results were found for the combination of A. brasilense HM053 with the application of the lowest doses of nitrogen. The use of 25% of the recommended nitrogen dose associated with this strain led to an increase of approximately 9.5% in the productivity of the strawberry plants compared to non-inoculated plants and full nitrogen dose. In both experiments, doses from 0 to 50% of nitrogen, mainly associated with the HM053 strain, showed promising results, indicating a reduction of 50% to 75% in the use of nitrogen fertilizers. In conclusion, replacing part of the nitrogen fertilizers needed for strawberry cultivation with bacteria of the genus Azospirillum could reduce production costs, increase productivity, and promote more sustainable agriculture.