Modulation of biochemical constituents, nutritional status, growth and flowering of Brunfelsia grandiflora via supplying diverse silicon sources

Recently, several countries have been using silicon (Si) fertilization in agricultural plants. The application of Si has a beneficial role on plant growth via affecting the cellular metabolites and physiological events. However, there are little findings that interpret the impact of different Si sources on physiological and agronomical traits of Brunfelsia grandiflora. Along the two seasons of 2022 and 2023, this study examined the impact of different Si sources (diatomite (DM), which comprises several elements and soluble SiO₂ (86-89%), potassium silicate K₂O₅Si₂ (PS), and silica-nanoparticles (SNP)) at different rates on biochemical constituents, nutritional status, growth and flowering of B. grandiflora. In addition to check treatment (no Si application), three levels of each of DM (2.5%, 5%, and 10%; DM2.5, DM5, and DM10, respectively), PS (1, 2 and 3 g L^-1; PS1, PS2 and PS3, respectively), and SNP (100, 200, and 300 mg L^{- 1}; SNP100, SNP200 and SNP300, respectively) were sprayed three times at four-week intervals, initiating 30 days after planting. The estimated data showed that DM and SNP as sources of Si had remarkable potential for ameliorating photosynthetic pigments, anthocyanin, nutrients content and secondary metabolites, hence the morphological and flowering traits of B. grandiflora. SNP had a positive impact comparable with DM or PS. Foliar application of SNP100 exhibited the maximum increases in plant pigments concentration with high healthy status and flower production. However, the supplementation of DM as a natural Si fertilizer should not be neglected where DM2.5 had acceptable growth and flowering potential compared to PS and untreated plants. Si supplementation, particularly with SNP and DM, improved morphological and floral traits by boosting pigment content (photosynthetic and anthocyanin), increasing phenolics and flavonoids level, and enhancing overall antioxidant capacity. The growers are advised to insert Si in fertilization programs of B. grandiflora to obtain high flower yield and quality. According to the availability, application of silica-nanoparticles at 100 mg L^{- 1} or diatomite 2.5% are costless and good practices to nourish B. grandiflora plants.