INFLUENCE OF SILICON ON PLANT UPTAKE OF HEAVY METALS AND METALLOID FROM SOIL

Abstract

The second-most common element in the crust of the earth is silicon, performs a variety of beneficial roles in soils and plants. It helps to reduce a variety of biotic (diseases and pest insects) and abiotic pressures (salt, drought and heavy metals).Si influences the heavy metal and metalloid uptake by plants through different mechanisms including (1) Si bioavailability in soil is influenced by biological factors, (2) by altering the soil's properties, (3) heavy metal co-precipitation, (4) heavy metals being changed into less solubility forms, (5) root architecturemodification, (6) controlling antioxidant enzymes, (7) gene expression that controls how wellheavy metals are absorbed by and transported to plants is regulated both up and down. In this chapter it is discussed about the various mechanisms involved in heavy metal and metalloid uptake by Silicon. The application of industrial by products (fly ash, steel slag etc.) decreased the conversion of soluble metals into insoluble metal silicates, phosphates, and hydroxides reduces the intake of heavy metals. Si application can reduce heavy metal bioavailability in soil. Silicon nanoparticles along with Pb-resistant microbes significantly reduced the Pb concentration in plants. Si application changes mineral composition of Fe plaque in rice root which decreases both shoot As and grain As. A significant decrease in Cd and Pb toxicity of wheat along with increased grain yield can be possible by the application of organic and inorganic silicon fertilisers. By preventing the production of low affinity cation transporter, silicon nanoparticles can decrease the uptake of Cd into rice grains and phloem (OsLCT1). Through decreased electrolytic leakage, lower levels of malondialdehyde and hydrogen peroxide, and increased antioxidant enzyme activity, si treatment reduces Cd toxicity in cotton. To assess the viability of using Si for the remediation of metalcontaminated soils, extensive field tests are needed