The amelioration of aluminium toxicity by silicon in higher plants : Solution chemistry or an in planta mechanism?

摘要: Aluminium (Al) toxicity is a very important factor limiting the growth of plants on acidic soils. Recently, number workers have shown that, under certain conditions, silicon (Si) can ameliorate toxic effects Al in hydroponic culture. The mechanism amelioration unclear, but three suggestions been put forward: Si-induced increase solution pH during preparation solutions: reduced availability due to formation hydroxyaluminosilicate (HAS) species those solutions plant growth; or planta detoxification. It now known that it possible make up and Si an order Which lowered prior addition: these cases has still observed. Amelioration also noted experiments where HAS minimal. These observations would suggest at least some circumstances, there component phenomenon. Several microanalytical investigations codeposition root cell walls. We propose model which walls are main internal sites aluminosilicate (AS) and/or Factors promoting AS/HAS this compartment include: high apoplastic pH; presence organic substances (e.g. malate); suitable local concentrations reactive forms Si, within surfaces wall matrix. All likely be toxicity.