Improving Sugarcane Biomass and Phosphorus Fertilization Through Phosphate-Solubilizing Bacteria: A Photosynthesis-Based Approach

Abstract

Phosphorus (P) is essential for sugarcane growth but often presents low agricultural use efficiency. This research evaluated the effects of <i>Bacillus velezensis</i> UFV 3918 (<i>Bv</i>), applied alone or with monoammonium phosphate (MAP), on sugarcane's physiological, biochemical, and biomass variables. Six treatments were tested in a completely randomized design: absolute control (AC), commercial control (CC, full MAP dose), <i>Bv</i> alone, and <i>Bv</i> combined with 1/3, 2/3, or full MAP dose. <i>B. velezensis (Bv)</i> and <i>Bv</i> + 1/3 MAP increased soil P availability by 22%, correlating strongly with physiological, biochemical, and shoot biomass variables. These treatments boosted total chlorophyll content (11.4%), electron transport rate (28.5%), and photochemical quenching (16.9%), resulting in higher photosynthetic efficiency. Compared with CC, net CO₂ assimilation, stomatal conductance, and carboxylation efficiency increased by 49.0%, 35.4%, and 72.9%, respectively. Additionally, amino acid content and leaf acid phosphatase activity rose by 12.1% and 13.8%. Key traits associated with biomass production included stomatal density (abaxial face), chlorophyll content, electron transport rate, intercellular CO₂ concentration, and leaf acid phosphatase activity. The results highlight the potential of <i>Bv</i> UFV 3918, particularly with reduced MAP doses, to improve sugarcane photosynthesis and biomass accumulation, offering a sustainable and cost-effective fertilization strategy.