The Influence of Silica on Bending Elastic Modulus of the Stalks of Two large Grass Species (Poaceae)
In this chapter potential mechanical functions of silica in land plants are analysed. The importance of silica for mechanical plant stability has often been quoted but rarely studied quantitatively. For that reason, the influence of silica inclusions on the bending stiffness of plants is analysed using two different approaches. In the first, the influence of higher amounts of silica were investigated in relation to the bending stiffness of sugar cane (Saccharum officinarium), an economically important grass. The results do not show a constant increase in bending stiffness with increased silica content, but at first a slight increase followed by a decrease. Since silica is assumed to improve plant mechanical stability, while its energy costs are 10-20 times lower than that of cellulose or lignin, the objective of the second experiment was to test if silica instead of lignin was deposited in the strained regions of the tall grass Miscanthus, in the case of static mechanical bending stress. The results showed that even though more silica was deposited in the strained regions on the convex side, lignin content increased as well and was obviously not replaced by silica. Our data indicate that the influence of silica on the bending stiffness is not significant, at least with the plant species and methodsused for our experiments.
KeywordsSilica Bending elastic modulus Influence of silica on plant stability Poaceae
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