Silicon in soils, plants and its important role in crop production: A review

Silicon in soil solution is present as silicic acid, at concentrations normally ranging from 0.1 to 2.0 mM, roughly two orders of magnitude higher than the concentrations of phosphorus. Cropping system cannot allow for recycling Silicon element by plants. The decrease of bioavailable-Si may have significant impacts on cereal crops. The assumption of the depletion of plant available-Si is still admissible, but new conspicuous have proven that phytoliths are a significant source of Silicon for plant. Plants uptake silicon in silicic acid form. Silicon concentrations vary greatly in plant aboveground parts, ranging from 0.1 to 10.0% SiO2 of dry weight basis or even higher. The difference in Si accumulation attributed to the ability of the roots to take up Si. It is obvious that most of the effects of Si were expressed through Si deposition on the leaves, stems, and hulls. In spite of Si has not been proven to be an essential element for higher plants, it is a beneficial element for the healthy growth and development and even productivity of many crop species, particularly for rice which contains about 10% SiO2 in shoots on a dry weight basis. The beneficial effects of Si are particularly distinct in plants exposed to biotic or abiotic stress. Silicon is effective in controlling various pests and diseases caused by both fungi and bacteria in different plant species. Silicon also exerts alleviative effects on various abiotic stresses including salt stress, metal toxicity, drought stress, radiation damage, nutrient imbalance, high temperature, freezing and so on. Also, Silicon has been widely reported to alleviate the plant water status and water balance, especially under various stress conditions in both monocot and dicot plants Numerous research studies showing that the application of Si enhances the tolerance of some plant species to toxic metals, including manganese Mn, zinc Zn aluminum Al, cadmium Cd and arsenic As. In addition, studies have shown that Si alleviates growth inhibition and oxidative damage.