Response of sugarcane under water deficit to amorphous silica doses: biomass, C:N:P homeostasis, and nutritional efficiency

Background and AimsClimate change intensifies water deficits in tropical regions, affecting sugarcane productivity. Silicon (Si) supplementation enhances tolerance to drought by improving the C:N:P balance and efficiency of nutrient conversion into plant biomass. The objective of this study was to evaluate the effect of Si doses on biomass production, nutrient use efficiency, and the C:N:P ratio in sugarcane under conditions of water restriction.MethodsThe experiment was conducted in a controlled environment for 150 days, employing a randomized block design with a 4 × 2 factorial arrangement. The treatments comprised four Si doses: 0 (control), 78, 117, and 156 kg ha−1, applied in the form of a fertilizer derived from amorphous silica (ASF), and two irrigation levels (50 and 20% of crop evapotranspiration – ETc).ResultsThe Si dose of 78.0 kg ha−1 promoted the greatest osmotic adjustment, reaching 0.39 MPa, which represents an increase of 12.0% compared to the control treatment. Cluster analysis showed that 78.0 kg ha−1 of Si associated with 50% of ETc reduced C concentrations, altered C:N:P ratios, improved C and N use efficiencies, and increased dry mass production in leaves and stalks.ConclusionThe optimal Si dose of 78.0 kg ha−1, equivalent to 300.0 kg ha−1 of ASF, promoted osmotic adjustment and modified the homeostatic balance of Si:C:N:P. This resulted in greater efficiency in the use of C and N, as well as greater accumulation of stalk dry matter in sugarcane plants subjected to water deficit.