A review of a decade research conducted in the Department of Soil Science, University of Tehran in the field of soil silicon chemistry and its role in plant nutrition

In modern agriculture, silicon (Si) is considered as an essential and anti-stress nutrient for a number of plants, especially grasses and C4. There are arguments confirming that it is a quasi-essential element in relation to plants growth, development and reproduction. The present study aims to review a decade research in the field of chemistry and plant nutrition of the Si in soil and plants in the Department of Soil Science and Engineering, University of Tehran. The objectives of this article is to present the most important achievements of researches in the field of Si efficiency of maize and soybean cultivars and to investigate the effect of Si application on nutritional, physiological and morphological characteristics of different plants including wheat, corn, sorghum, etc. under stress conditions and also to assess the effect of Si application on immobilization of heavy metals in the soil. General conclusions of this study show that Si supplied by both chemical fertilizers and silicon-soluble bacteria, increase plant growth and yield via increasing the root system of plants, regulating the biosynthesis of plant hormones, stimulating the production of some antioxidant enzymes, increasing resistance to salinity/ drought/heavy metal toxicity stresses and also increasing plant accessibility to some nutrients such as phosphorus and nitrogen. In addition to these results, the fraction of Si in different soils have been studied and analyzed. It seems by focusing on researches done on this element in the "soil, plant and rhizosphere", it can be hopefull that these results will be more practical in the future of the country's agriculture.