Silicon deprivation causes physical abnormalities in wheat (Triticum aestivum L.)

The Earth's surface including its soils consists largely of silicate minerals, and terrestrial plants absorb large amounts of silicon. Not so the plants grown for experimental purposes in solution culture, for not a single formulation of the widely used culture solutions includes silicon, the element not being considered generally <<essential>> for higher plants. We here show that Si-deprived wheat (Triticum aestivum L.) plants (-Si) differ greatly from Si-replete (+Si) ones in certain physical features. The friction force that must be overcome if the heads of +Si wheat are to slide down an inclined plane, a measure of roughness, was greater than for -Si wheat heads. Energy dispersive X-ray microanalysis and chemical analysis revealed the presence of Si in the awns of +Si plants but none or very little in those of -Si plants. The large physical differences measured in these experiments show wheat plants grown in conventional (-Si) cultures to be in some respect experimental artifacts. The over 130-year-old practice of growing experimental plants in -Si solution cultures should be reconsidered. We recommend that Si be included routinely in the formulation of nutrient solutions.