INOCULANTES MICROBIANOS NO CRESCIMENTO, PRODUTIVIDADE E VARIÁVEIS TECNOLÓGICAS DA CANA-DE-AÇÚCAR

Abstract

Sugarcane cultivation is very important for industry, as it produces various by-products. One strategy for reducing sugarcane production costs involves the selection and use of diazotrophic bacteria. Species such as Azospirillum brasilense and Nitrospirillum amazonense have been studied aiming to reduce the use of nitrogen fertilizers. This work was carried out to test doses of inoculants, consisting of Azospirillum brasilense and Nitrospirillum amazonense, as well as doses of nitrogen fertilizer, in sugarcane cultivation, to reduce dependence on nitrogen fertilizers. Three experiments were carried out at Fazenda São Frank in the municipality of Acreúna-GO, one in pots (2022/23 harvest) and two in the field (2022/2023 and 2023/2024 harvests). The variety used in all experiments was IAC95-5094. Both in the pot and field experiments, the experimental design was randomized blocks, consisting of 12 treatments and 5 replicates. The treatments were: control (without inoculation and without urea); Azospirillum brasilense with 100, 300, and 500 mL ha⁻¹ (two applications); Azospirillum brasilense with 100, 300, and 500 mL ha⁻¹ (three applications); urea (1 kg/ton of sugarcane); urea (0.5 kg/ton of sugarcane + 100 mL ha⁻¹ of Azospirillum brasilense); urea (0.75 kg/ton of sugarcane + 100 mL ha-1 of Azospirillum brasilense), urea (1 kg/ton of sugarcane + 100 mL ha-1 of Azospirillum brasilense) and Nitrospirillum amazonense (100 mL ha-1). Leaf assessments were performed every 30 days, including: number of tillers, tiller height, tiller diameter, cane height, cane diameter, number of internodes, node width, node length, number of canes, chlorophyll, total recoverable sugar, wet cake weight, saccharimeter reading, Brix, tons of Brix per hectare, and tons of cane per hectare. Inoculation with Azospirillum brasilense promoted an increase in chlorophyll, tiller diameter, and number of internodes in sugarcane grown in pots, demonstrating morphological stimulation potential. In two field evaluation cycles, for most technological variables, there was no difference between treatments with urea, inoculation of diazotrophic bacteria, or their combinations. The feasibility of using growth-promoting bacteria as an alternative to industrialized nitrogen fertilization is reinforced by this study, especially in areas with high levels of soil fertility and organic matter. This practice proves to be strategic in the face of the modern agriculture challenges, combining agronomic performance, reduction of inputs, and mitigation of environmental impacts.