Inoculating Azospirillum brasilense and Nitrospirillum amazonense in sugarcane: an approach beyond the biological nitrogen fixation

• Grant number: 21/02358-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2022
• End date: July 31, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Carlos Alexandre Costa Crusciol
• Grantee: Mariley de Cassia da Fonseca
• Host Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Sugarcane (Saccharum spp.) is one of the main crops of economic interest in the world, serving as a raw material for the production of ethanol, sugar and bioenergy. Microorganisms play several roles in the ecosystem, including Plant Growth-Promoting Bacteria (PGPBs), which can bring several benefits to the cultivation of sugarcane. Evaluating the effect of these bacteria on their physiology, and the benefits they can bring to this crop, can be alternatives to improve the use of fertilizers by plants, minimize possible risks to the environment, reduce dependencies on fertilizers, seeking sustainability and soil conservation. Thus, the present study aims to verify I) whether the inoculation of Azospirillum brasilense and/or Nitrospirillum amazonense increases the physiological parameters, productive performance and stalk technological quality of sugarcane, in addition to altering the rhizosphere exudation of organic acids and the microorganisms that are recruited by the sugarcane rhizosphere; and II) the combination of A. brasilense and N. amazonense reduces the dependence on nitrogen fertilizers through increasing sugarcane physiological responses. To access these objectives, two studies will be performed. The first experiment will be carried out in greenhouse conditions, with inoculation of A. brasilense and/or N. amazonense (i.e., applied alone or in combination) in order to evaluate the crop nutrition, photosynthetic parameters (gas exchange, Rubisco and PEPCase activity), carbohydrate concentration, root exudates and soil microbiome through 16S rRNA sequencing. The second part of this first experiment will be performed during two years in field conditions, using the same treatments, in order to validate the photosynthesis results, stalk yield and stalk technological quality. The second experiment will be carried out in field conditions during two years, applying both PGPBs (A. brasilense and N. amazonense) combined in the sugarcane fertilized with 0, 50, 75 and 100% of the nitrogen recommended dose (120 kg ha-1). In this study, nutritional status, photosynthetic parameters (gas exchange, Rubisco and PEPCase activity), biometric parameters, stalk and sugar production, and stalk technological quality will be performed. (AU)