Silicon Contribution Via Nutrient Solution in Forage Plants to Mitigate Nitrogen, Potassium, Calcium, Magnesium, and Sulfur Deficiency

This study aimed to evaluate whether silicon application in the nutrient solution is efficient in relieving stress caused by nutrient deficiency (N, K, Ca, Mg, and S) in the forages BRS Zuri (Panicum maximum) and BRS RB331 Ipypora (Brachiaria ruziziensis × Brachiaria brizantha). Two experiments were carried out in a greenhouse with both forages, with plants grown in a nutrient solution in pots filled with washed sand. Treatments were arranged in a completely randomized block design, with five replications and consisted of complete solution (control) and individual omission of nitrogen, potassium, calcium, magnesium, and sulfur in the absence (−Si) and presence of silicon (+Si) at a concentration of 2 mmol L−1 applied via nutrient solution as stabilized potassium sodium silicate. The dry mass of the shoot, root, and clump residual material, accumulation and use efficiency of nutrients, and the description of symptoms of nutritional deficiency were evaluated. Silicon addition in the nutrient solution favored shoot dry matter production and root dry matter production of both forages, in treatments with K, Ca, and Mg omission; the same effect was not observed for N and S. We conclude that the application of silicon attenuates the effects of potassium, calcium, and magnesium deficiency in forages BRS Zuri and BRS RB331 Ipypora, as it increases the accumulated shoot dry mass, due to the greater efficiency in the use of these nutrients. The beneficial effect of silicon was not important in forage plants with nitrogen and sulfur deficiency.