Silicon modifies C:N:P stoichiometry and improves the physiological efficiency and productivity of sorghum grown under nutritional sufficiency.

Abstract The benefits of silicon (Si) in plants under nutritional sufficiency may be involved in the modification of C:N:P stoichiometry, favoring homeostasis, cell metabolism and physiological processes, increasing biomass. However, studies in the grain sorghum are still scarce. Therefore, the objective was to evaluate the effect of Si supply on C:N:P stoichiometry, physiological response, and production of grain sorghum. The experiment was carried out in pots with four concentrations of Si: 0; 1.2; 2.4; and 3.6 mmol L-1. The increase in Si concentration linearly increased the dark green color index and stomatal conductance, although photosynthetic rate and transpiration increased up to the concentration of 1.9 and 2.0 mmol L-1, respectively. The application of Si decreases C:Si, C:N e C:P stoichiometric ratios and favors photosynthesis, resulting in an increase in grain biomass. Dry matter was favored by increasing Si concentrations up to 1.4; 2.3; 2.1; and 2.2 mmol L-1 for root, shoot, whole plant, and grain, respectively. Thus, the results reveal that the benefit of Si in sorghum under nutritional sufficiency occurs due to the induction of optimization of C:N:P stoichiometry, consequently increasing metabolic efficiency and optimizing the efficiency of the use of C, providing increases in the photosynthetic and biomass production.