Foliar application of silicon sources and shading levels in Peltophorum dubium (Spreng.) Taub.

Aplicação foliar de fontes de silício e níveis de sombreamento em Peltophorum dubium (Spreng.) Taub.

Abstract

Depending on the intensity and ecological successional classification of plants, light availability can become an unfavorable condition for producing high-quality seedlings. We hypothesized that applying silicon sources might contribute to inducing tolerance to different shading levels for Peltophorum dubium (Spreng.) Taub. seedlings. Two independent experiments were developed: I) the application of five doses of silicon oxide (SiO₂: 0.0; 1.0; 2.0; 4.0; and 6.0 g L^-1); and II) the application of five doses of potassium silicate (K₂SiO₃: 0.0; 5.0; 10.0; 15.0; and 20.0 mL L^-1 of water). Both were associated with three shading levels: 0% (direct sunlight), 30%, and 50%. In experiment I, we observed that seedlings were more responsive to shading levels and had little influence from foliar application of SiO₂, with higher growth, biomass, and quality values when grown under direct sunlight (0% shading). In experiment II, the foliar application of 20.0 mL L^-1 of K₂SiO₃ contributed to greater heights under 0% and 30% shading. Meanwhile, under 50% shading, the dose of 5.0 K₂SiO₃ favored the species' growth. The application of K₂SiO₃ favored the increase in the dry mass of the aerial part (DMAP). The highest biomass production and seedling quality occurred under 0% and 30% shading. The 50% shaded environment was most unfavorable to the growth and quality of P. dubium seedlings. Even though the seedlings were not very responsive to silicon sources, K₂SiO₃ provided a greater response than SiO₂. High-quality seedling production is favored when the seedlings are grown under direct sunlight (0% shading).

Keywords:
silicon oxide; potassium silicate; light availabilities; physiological adjustments; phenotypic plasticity