we are working on improving salinity tolerance of crop plants using exogenous application of silicon. i would like to know the normal range of the concentration of silicon in crop plants?
The normal range of Si in plants is highly variable. The generalisation is that the [Si] higher in monocots than dicots, e.g. leaves of lettuce may have as little as 0.1% and of rice 10% or more. However there are specific cross overs.
Recovery of plant Si requires either digestion with HF in an acid mixture, or by fusion of the ash with alkaline salts in a metal crucible. The latter needs care to get good recoveries: do not believe otherwise. The extracted Si can be measured either colorimetrically as the reduced molybdate when formation of the P complex is suppressed, or by ICP optical emission.
Silicon concentration in ten horticultural plants, viz. meadow sage (Salvia sylvestris), tickseed (Coreopsis verticillata), garden phlox (Phlox paniculata), New England aster (Symphyotrichum novae-angliae), Chinese astilbe (Astilbe chinensis), coral flower (Heuchera hybrid), garden zinnia (Zinnia elegans), French marigold (Tagetes patula), sweet basil (Basil spp.), and rosemary (Rosmarinus officinalis) were determined by Hogendorp et al. (2012). Si concentration in coral flower and French marigold varied from 55 to 624 mg/kg, in sweet basil, rosemary and salvia varied from 1052 to 1070 mg/kg, in astilbe was 1411 mg/kg, in coreopsis and phlox varied from 2219 to 2427 mg/kg, and aster and zinnia varied from 4796 to 5365 mg/kg.
Nice discussion ....Some exerpts from the paper entitled Silicon: A Beneficial Substance by Joseph Heckman published in Better Crops ( Better Crops/Vol. 97 (2013, No. 4)...
Plant tissue Si concentrations will vary widely depending on plant species and the soluble Si concentration in the soil. It is not unusual to fi nd Si concentrations in plants at levels comparable to or above those for macronutrients (up to a few
percent of dry weight). Grasses and monocots generally accumulate higher concentrations of Si than dicots (approx. 0.1% Si). Concentrations as high as 10% Si are possible in some plant species such as Equisetum (Horse tail).
Optimum Si concentrations have not been established for most crops. Research conducted on soils in New Jersey indicates concentration ranges that may occur for some crops. For example, adding supplemental Si increased concentrations in pumpkin leaf tissue from 700 to 3,500 mg Si/kg, in corn stem tissue from 1,300 to 3,300 mg Si/kg, wheat fl ag leaves from 1,530 to 11,750 mg Si/kg, and Kentucky bluegrass leaves from 4,200 to 7,200 mg Si/kg. Different parts within the same plant can also show large differences in Si accumulation. For example, polished rice contains 0.5 g Si/kg, while the rice hull may contain 230 g Si/kg (Currie and Perry, 2007).
As concentrações de Si em plantas são bastante variáveis, dependendo da espécie e níveis de Si no ecossistema de cultivo. Contudo, condições de estresse salino podem mudar os teores de Si nos tecidos vegetais, sobretudo pela interação entre Na e Si no solo que pode limitar a absorção de Si e outros minerais. Em sentido complementar, muitas alterações metabólicas podem ocorrer nos organismos vegetais pelo efeito tóxico de Na. A sugestão para esta pergunta é que o autor diga exatamente que culturas pretende avaliar para que possamos contribuir de forma mais objetiva. Em geral, acredito que as literaturas em anexo possam ajudar.
Recomendo consultar as contribuições do Prof. Dr. Gaspar Korndorfer.