Function of silicon and its mechanisms in plant physiology: A review

Abstract

Silicon (Si) is the most prevalent macroelements in soil, performing an essential function in healing plants in response to environmental stresses. The assumption of the depletion of plant available-Si is still admissible, but new evident have establish that phytoliths are a denoting derivation of Silicon for plant growth. Biotic and abiotic stress factors can adversely affect the agricultural productivity pleading to physiological and biochemical damage to crops. Therefore, the most effective way to overcome such negative effects is to increase the resistance to stresses. Silicon plays a vital role in reducing the negative effects of abiotic and biotic stresses on plants. Silicon is accumulated in the cell walls and intercellular spaces and increase its strength, and thus it has beneficial effects on disease infestations in especially small grains. In addition, application of silicon may reduce the effects of environmental stresses on plants while making effective use of plant nutrients such as nitrogen and phosphorous. Reducing, the toxic effects of heavy metals in soil. It may protect the foliage and increase light uptake and reduce respiration. However, the concentration of Si depends on the plants genotype and organisms. Physiological mechanisms and metabolic activities of plants may affected by Si treatment. Generally, plant physiologists consider an essential element by two criteria. (a): if a deficiency of it makes it impossible for the plant to complete its life cycle, therefore, the element must be directly involved in the inorganic nutrition of the plant. (b): it is contributed as a part of the molecule of an essential plant constituent or metabolite. It is by the first criterion that the essentiality of the elements now known to be essential has been established. Conceptually, it is a simple, operational definition. In practice, it is not necessarily easy to apply if, as is the case with Si, it is difficult to create and maintain an environment adequately purged of the element. Peptides as well as amino acids can effectively create polysilicic species through interactions with different species of silicate inside solution. The carboxylic acid and the alcohol groups of serine and asparagine tend not to engage in any significant role in polysilicates formation, but the hydroxyl group side chain can be involved in the formation of hydrogen bond with Si (OH) 4. The mechanisms and trend of Si absorption are different between plant species. Furthermore, the transportation of Si requires an energy mechanism; thus, low temperatures and metabolic repressors inhibit Si transportation.