A study on the uptake of silica source by maize seeds was conducted under hydroponic conditions and pot experiments supplemented with nano-SiO2 (20–40 nm) extracted from natural source (rice husk) and their bulk silica counterparts such as micro-SiO2, sodium silicate, and silicic acid. Employing hydroponic incubation experiment to explore the nanosilica absorption is a novel approach in maize. Seeds after different silica source treatments were analyzed with regard to germination percentage (GP %), elemental analysis, and root growth parameters to investigate the efficiency of nano-SiO2. Hydroponic culture studies revealed an increase in GP (95.5%), dry weight (6.52±0.2), silica accumulation (18.2%), and better nutrient alleviation in seeds exposed to nano-SiO2 than in those exposed to bulk sources. Variations in the pH, conductivity and SiO2 content in the hydroponic solution reflect the utilization of silica by seeds. Maize seeds and roots during pot experiments absorbed nano-SiO2 better when compared with absorption of other micron sources, which led to the conclusion that nano-SiO2 can be used as an immediately utilizable source for plants.

A highly pure, small particle-sized and high surface area nano silica powder was prepared from rice husk using alkali extraction, followed by an acid precipitation method. The composition, phase, morphology, size and surface area of the as-synthesised nano silica powder was investigated by energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, particle size analyser and BET surface area analyser. High-purity nano silica powder was obtained by sodium hydroxide (NaOH) purification treatment (0.5, 1, 1.5, 2 and 2.5 N). The high purity of silica (∼99.9%) was obtained at 2.5 N NaOH treatment. The pure nano silica powder that is obtained shows an average particle size of ∼25 nm with a high-specific surface area (SSA) of 274 m² g⁻¹, with an average pore diameter of 1.46 nm.

The study was aimed at evaluating the effect of nanosilica and different sources of silicon on soil properties, total bacterial population and maize seed germination. Nanosilica was synthesised using rice husk and characterised. Silica powder was amorphous (50 nm) with >99.9% purity. Sodium silicate treated soil inhibited plant growth promoting rhizobacteria in contrast to nanosilica and other bulk sources. Surface property and effect of soil nutrient content of nanosilica treatment were improved. Colony forming unit (CFU) was doubled in the presence of nanosilica from 4 × 10 ⁵ CFU (control) to 8 × 10 ⁵ CFU per gram of soil. The silica and protein content of bacterial biomass clearly showed an increase in uptake of silica with an increase in nanosilica concentration. Nanosilica promoted seed germination percentage (100%) in maize than conventional Si sources. These studies show that nanosilica has favourable effect on beneficial bacterial population and nutrient value of soil.

In this study, maize treated with nanosilica (20–40 nm) is screened for resistance against phytopathogens such as Fusarium oxysporum and Aspergillus niger and compared with that of bulk silica. The resistivity is measured for disease index and expression of plant responsive compounds such as total phenols, phenylalanine ammonia lyase, peroxidase and polyphenol oxidase. The results indicate that nanosilica‐treated plant shows a higher expression of phenolic compounds (2056 and 743 mg/ml) and a lower expression of stress‐responsive enzymes against both the fungi. Maize expresses more resistance to Aspergillus spp., than Fusarium spp. These results show significantly higher resistance in maize treated with nanosilica than with bulk, especially at 10 and 15 kg/ha. In addition, hydrophobic potential and silica accumulation percentage of nanosilica treated maize (86.18° and 19.14%) are higher than bulk silica treatment. Hence, silica nanoparticles can be used as an alternative potent antifungal agent against phytopathogens.