Study of morphology and chemical composition of phytoliths on the surface of paddy straw

Silica though nutritionally insignificant plays important role in plants. Most of the silica from absorbed water is precipitated and deposited inside or between plant cells to form ‘phytoliths’ which provide mechanical strength and aid in protection from physical, chemical and biological stresses of the plant. Phytoliths occur in numerous monocot and dicot plants. These amorphous silica bodies take various shapes and sizes depending on their intracellular or intercellular templates, that certain morphological forms are even specific to families or species. In the present study, paddy straw samples were examined using scanning electron microscopy to visualise silica deposition (phytoliths) on the surface followed by Energy dispersive X-ray spectroscopic analysis to determine the composition of the observed phytoliths. A protective coat of silica covering the entire surface of paddy straw, consisting of phytoliths of distinct shapes and sizes and diffused silica deposits, was observed. Phytoliths observed were morphologically different, some forms being exclusive to certain regions of paddy straw. Indiscrete deposits of silica were found between and around phytoliths. Elements like Fe, Al, K, Mg, Cu and Ca were detected in addition to Si, O and C in phytoliths indicating that phytolith deposition occurs as a part of the inherent mineral detoxification system in paddy. The surface silica deposits, being the first to encounter physical and biological stress factors, play the major role in resistance of the plant.