Silica Absorption by Plants
Silica dissolves in water to a small extent and below pH7 exists in solution essentially in a non-polar form. In this respect it contrasts with nutrient cations and anions and a study of its uptake by plants was thought to be of interest. It was found that in common with the absorption of ionized solutes the entry of silica into plants appears to require the expenditure of metabolic energy since the process is sensitive to both metabolic inhibitors and variations in temperature. Furthermore, except under conditions of very low humidity, silica enters barley plants at a relatively greater rate than the water lost in transpiration, and its concentration in the xylem sap of bean plants may be greater than that in the external solution.
Source: • Journal of Experimental Botany, Vol. 17, No. 52