Silicon Application Increases Biomass Yield in Sunflower by Improving the Photosynthesizing Leaf Area

Sunflower is an oilseed plant important for food and biodiesel production. One cheap way to increase sunflower production is by the application of silicon (Si), which has shown to be beneficial in plants under a series of stresses. We analyzed if the application of Si in sunflower affected the CO2 assimilation, N uptake, leaf quantity and quality, and total biomass yield. No difference was observed in the gas exchange measurements or in leaf N concentration. The total leaf area increased in plants applied with even the lowest dose of Si, with no loss to the net CO2 assimilation rate or leaf N concentration. The higher total leaf area of the plants treated with Si resulted in an increase of the total CO2 assimilation by the plant. Plants treated with any dose of Si had an increase of 24–39% in biomass yield. Statistically, the increase in biomass was explained by the total CO2 assimilation in the plant. If the increment in biomass yield is proportional to the oilseed production, we estimate that Si application in sunflower can increase profit by up to 22%. Large-scale experiments are needed to better determine the proper Si dose to be applied and the oilseed production.