Silica accumulation in Triticum aestivum L. and Dactylis glomerata L.

Abstract

The silica accumulation in orchard grass (Dactylis glomerata L.) and wheat (Triticum aestivum L.) has been studied in plant samples grown under defined conditions in a pot trial. The plant habit and the quantity of biomineralised silica within the selected Gramineae depend to a remarkable extent on the soil. The plants grew with different soil pH values and silica additives. By means of atomic absorption spectrometry, the silicon enrichment in different plant parts was determined. In dried plant parts the silica bodies can be well distinguished by variable pressure scanning electron microscopy in the back scattering mode. They are located in silica cells below the epidermis and in epidermal appendices (bristles, prickle hairs). The silica bodies showed a defined morphology, structure and composition which was elucidated by the combined performance of scanning electron microscopy in combination with X-ray spectroscopy, solid-state nuclear resonance, X-ray diffraction and Raman spectroscopy. The composition was near to stoichiometric SiO(2) (41 weight% silicon, 56 weight % oxygen), and the SiO(4/2)tetrahedra were arranged preferentially in three-dimensional networks; a smaller proportion was in chains and layers. The silica bodies with an overall amorphous structure contained crystalline precipitates, which could be indexed by alpha-quartz.

Effect of silicon fertilizers on silicon accumulation in wheat

“…40% Si). This result is in accordance with earlier NMR measurements (Dietrich et al, 2002(Dietrich et al, , 2003. On the other hand, the Si content of the leaves in the epidermal cell wall close to the leave veins depends strongly on the nature of the silica compound added to the soil.…”

Benefits of plant silicon for crops: a review

“…In the leaves, Si is at first preferentially deposited in the abaxial epiderm, and then in both epiderms as the leaf grows (Hodson and Sangster 1988). Among those tissues, phytoliths are found in specific cells called silica cells located on vascular bundles and/or are present as silica bodies in bulliform cells, fusoid cells or prickle hairs in rice (Ma and Yamaji 2006), wheat (Dietrich et al 2003), or bamboos (Motomura et al 2004). These specific allocations observed in Poaceae have been taken both as proofs of passive or active Si transport, depending on the allocation (Motomura et al 2004).…”

“…1). Phytoliths may contain impurities such as Al, Fe, Ti, Mn, P, Cu, N, and C (Clarke 2003), but are usually nearstoichiometric silica (Dietrich et al 2003), the formula of which is [SiO n OH (2n − 4) ] m (with n<2 and m large). Phytoliths can be assembled without any energy by polymerization of silicic acid when its concentration exceeds 2 mM (Ma and Yamaji 2006).…”

Alleviation of abiotic and biotic stresses in plants by silicon supplementation

“…Inanaga et al (1995) found that silicon play a key role in formation of linkage between lignin and carbohydrate in association with phenolic acids. Amorphous silica is the only form of silicon in plants (Ding et al 2008) which can precipitate in the plant cells which are known as phytoliths.These are not found throughout the plant (Prychid et al 2003) but present in leaf epidermis, root epidermis and in the cell membranes of vascular bundle at transpiration sites.Phytoliths are found in specific cells known as silica cells located in the vascular bundles or present as silica bodies in bulliform cells, fusoid cells or prickle hairs in rice , wheat (Dietrich et al 2003) and bamboos (Motomura et al 2004).Phytoliths can be assembled by polymerization of silicic acid when its concentration exceeds 2 mM . The location and proportion of phytoliths may vary with the age of the plants and species (Ponzi and Pizzolongo, 2003).…”