Photosynthesis and growth of the sweet sorghum supplemented with silicon

Silicon is a major element in plants, being essential for some species and beneficial for others, with important role in plant metabolism. Several families of monocotyledons have the ability to absorb high amounts of this compound, being considered silicon accumulators. This is the case of sweet sorghum (Sorghum bicolor L. Moench), a plant with C4 carbon metabolism, with high photosynthetic activity, and great potential for ethanol production; its residual biomass can also be used for energy cogeneration in sugarcane production systems. The aim of this work was to evaluate the effect of silicon, in the form of sodium metasilicate, on sweet sorghum plants cultivated under hydroponic conditions and without stress of biotic or abiotic origin. There is a linear increase in silicon content in leaves, stalks and roots as a function of increasing doses of this element in the substrate. Silicon supplementation in sweet sorghum increases photosynthesis rates, water use efficiency and leaf biomass. The best dose of silicon for maximum photosynthetic efficiency is 70 mg L 1 of Si in the nutrient solution.