Bactérias fixadoras de nitrogênio no desenvolvimento, produção e qualidade da cana de açúcar

Abstract

The sugar cane has a high requirement for nitrogen being considered one of the most nutrients absorbed by culture. The mineral fertilizer is the most used for the supply of nutrients and is a large part of production costs, which makes the search for alternatives a major contribution of research institutions. Results indicate that 20 to 60% of the nitrogen present in sugar cane is from biological fixation. This study aimed to evaluate the development, production and technological quality of sugar cane culture in response to the application of nitrogen fixing bacteria and the effects of nitrogen fertilization on nitrogen fixation process. For this, two inoculants were used, both liquids, one based on a mixture of five strains diazotrophic and the other containing the bacteria Azospirillum brasilense. The experiment was installed in the experimental area of the Federal University of Uberlândia Campus Umuarama in the year of 2014. The design was a randomized block in a factorial 6 x 2, and 6 types of inoculation management consisting of combinations of inoculants and forms application, in the presence or absence of nitrogen fertilization at planting, with four replications. The first experiment, plant cane, lasted 263 days and the second phase of the experiment, soca cane was conducted for 220 days. We evaluated the biometric parameters and the technological quality of sugarcane. The results were submitted to analysis of variance by Scott-Knott test at 0.05 significance. The application of management of inoculants 1 and 2 foliar spray show increases in the number of green leaves of the plant cane. Application of inoculant 2 foliar spraying, the plant cane, favors the increase in leaf N content. Nitrogen fertilization promotes increase in biomass (fresh and dry) and the leaf N concentration in plant cane cycle. In the cycle of ratoon cane, nitrogen fertilization positively influences the number of industrial tillers, the number of leaves (green and dead), the index of leaf area, biomass (fresh and dry) and leaf N content. The application of inoculants containing diazotrophs associated with nitrogen fertilizer does not promote positive effect on the technological quality of plant cane and ratoon cane, negatively influences the variables Brix, Pol and ATR.