Are Nanosilica, Potassium Silicate and New Soluble Sources of Silicon Effective for Silicon Foliar Application to Soybean and Rice Plants?

Abstract

Foliar application of silicon (Si) is an effective way of supplying this beneficial element to plants. The emergence of new potential liquid sources for foliar application requires studies to assess the effectiveness of supplying Si to plants, as well as its effects on agronomic performance indicators. In this respect, the present study evaluates the effect of four sources (stabilized silicic acid; nanosilica; potassium silicate; and stabilized potassium sodium silicate) and four concentrations (0, 0.5; 1.0; 1.5 g L−1) of Si by foliar application in soybean and rice plants. An experiment was conducted for both species. The plants were grown in a greenhouse in 7 dm3 pots filled with vermiculite and nutrient solution. Four foliar application were performed during growth of the species. In both experiments, the dark green color index, electrolyte leakage, Si content, Si accumulation, shoot dry weight and production components were evaluated. In both species, all sources were effective to foliar application up to 1.2 g L−1 Si. Stabilized potassium sodium silicate increased shoot Si accumulation and grain production, being effective for foliar application in soybean and rice at around 1.0 g L−1 Si. The application of 1.5 g L−1 Si with nanosilica resulted in an improvement in shoot dry weight and grain production for both species. Maybe, its use can be more effective if applied more times during the plant life cycle or in higher concentration but more studies should be performed to determine its potential. Stabilized silicic acid can become an interesting source of silicon but need to be improved.