Phosphorus solubilization in sugarcane under Bacillus velezensis UFV 3918 and different doses of mono ammonium phosphate

Author(s)

Hariane Luiz Santos

• Document type: Master's Dissertation
• Press: Botucatu. 2023-03-20.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agronômicas. Botucatu
• Defense date: 2023-03-03
• Advisor: Marcelo de Almeida Silva

Abstract

Sugarcane (Saccharum spp.) has international prominence due to the growing worldwide demand for sugar and ethanol from renewable sources; being a promising bioenergy crop to reduce dependence on crude oil and mitigate greenhouse gas emissions. However, fertilization is one of the most critical factors to achieving high yields, especially phosphate fertilization, since phosphorus (P) is involved in several metabolic processes in plants and is one of the nutrients that most limit the yield and longevity of sugarcane fields. In this sense, inoculation of bacteria can be an alternative since some strains can hydrolyze insoluble compounds of organic and inorganic P to a soluble form that can be assimilated by plants, besides producing phytohormones responsible for plant growth, providing an ecologically correct and economically viable approach to overcome the fixation of P and its subsequent uptake by plants. Based on the assumption that the bacteria can allow the reduction of P doses, without harming the photosynthetic efficiency and production of sugarcane, the present research was conducted to analyze the morphological, physiological, biochemical, and nutritional responses of sugarcane, as well as evaluate the chemical and microbiological responses of the soil, to the inoculation of Bacillus velezensis UFV 3918 and different doses of mono ammonium phosphate (MAP). The experiment was conducted in a protected environment, in an entirely randomized design with six treatments [absolute control (AC); commercial control (CC) (recommended dose of MAP - 3/3 MAP); B. velezensis UFV 3918 (Bv); Bv+1/3 MAP; Bv+2/3 MAP and Bv+3/3 MAP] and four replicates. In chapter 1, sprouting variables, biometrics, stomatal density, gas exchange, chlorophyll a fluorescence, photosynthetic pigments, as well as protein, sugar, and amino acid contents and leaf acid phosphatase activity and biomass yield and partitioning were evaluated. And in chapter 2, root variables, soil and plant tissue macro and micronutrient content, nutrient use efficiency, P availability adaptation efficiency, nutrient accumulation, nutrient uptake by root length, and microbiological indicators were evaluated. The association of B. velezensis and reduced doses of P (Bv and Bv+1/3 MAP) promoted growth increment, evidenced by plant height, leaf area, and shoot biomass, equivalent to plants grown with 100% of the recommended dose of MAP, besides providing an increase in instantaneous carboxylation efficiency and leaf biochemical parameters. In addition, Bv and Bv+1/3 MAP increased root volume, shoot P accumulation, and macro- and micronutrient uptake by roots, as well as increased soil basal respiration, and fluorescein diacetate, urease, and acid phosphatase activities compared to the CC. Using B. velezensis UFV 3918 and reduced doses of phosphate improved the photosynthetic efficiency and biomass production of sugarcane, besides benefiting soil microbial and enzymatic activity, which reflected in nutrient uptake, evidencing that this is a strategy for sugarcane fertilization with reduced economic and environmental impact. (AU)

• FAPESP's process: 21/02991-0 - Phosphorus solubilization in sugarcane submitted to Bacillus subtilis BV 09 and different doses of monoamonic phosphate
• Grantee: Hariane Luiz Santos
• Support Opportunities: Scholarships in Brazil - Master