Status of Silicon in Ecosystem, Silicon Solubilization by Rhizospheric Microorganisms and Their Impact on Crop Productivity

Silicon (Si), a beneficial element, plays an overwhelming role in not only improving the crop productivity but also provides resistance against various biotic (insects and pathogens) and abiotic (salt stress, heavy metal toxicity, nutrient toxicity, ultraviolet radiation, drought condition) stresses. It may be considered as the only element which has multifaceted role in boosting the crop productivity in future against various environmental stresses. In spite of the abundance of Si in soil, it is not available for plant uptake. As a result, present scenario of agriculture demands to improve plant available Si for improving crop productivity across the world. One way is to apply silicon fertilizers which sometimes become very costly for the farmers to afford. However, an alternative is to utilize the potential of soil microorganisms in solubilizing silicates from minerals. Numerous studies have indicated that soil microorganisms, viz., bacteria and fungi, have the capacity to dissolve silicon from different primary minerals. Hence, in this chapter, we made an attempt to explore how silicon accumulates in different microorganisms, sources and sinks of terrestrial silicon cycle, role of microbes in silicate weathering, importance of rhizosphere microbes in solubilizing silicates, and the impact of silicate solubilizing bacteria on crop productivity.