Silicon uptake from different pools by wheat
2 Institute of Soil Landscape Research, ZALF
P 1.23 in Ecosystem Function
Silicon (Si) is the second most abundant element of earth´s crust and thus plays an important role in global matter cycles. Although Si is a quantitatively major inorganic constituent of higher plants, it is generally not considered to be essential. However, Si has beneficial effects on plant growth due to alleviating various abiotic and biotic stresses. These beneficial effects are mostly associated with the ability of plants to accumulate amorphous Si (phytogenic Si). Phytogenic Si is the most active Si pool in the soil in terrestrial biogeosystems because of its high surface:volume ratio, low crystallization and high solubility.
The aim of our study was to elucidate the effect of Si pools on Si uptake by wheat. Wheat plants (Triticum aestivum L.) were cultivated on different substrates: crystalline (quartz, anorthite), amorphous (Si gel) and soluble Si (1 mmol Si solution). After harvesting the plants were digested with a microwave and Si content of stems and roots were determined with ICP-OES.
Plants cultivated on Si gel and solution had the highest Si content (3.0 and 1.2% of dry matter) of stems which indicates that Si uptake by wheat depends on the conversion of the Si containing substrate into silicic acid. Total Si content of stems after 15 days was higher than calculated Si content due to Si uptake solely based on transpiration stream. This implies that Si uptake by wheat contains additionally an active component. Furthermore, plants grown on amorphous and soluble Si pool showed a higher structural stability and were less affected by mold than plants grown on crystalline Si pools and Si free substrate.