Interaction between silicon and aluminium in conifers

Abstract

Aluminium toxicity is one of the major limiting factors in plant growth in acidic soils. The Al³⁺ ion is believed to be an important component in determination of Al toxicity in plants and the availability of Al in the medium is affected by pH and presence of Al complexes in the solution. Aluminium is known to be toxic to plant growth, whereas Si is generally regarded as a beneficial element. Research suggests alleviation of Al toxicity by Si in hydroponic solution or in field conditions. While some results have been contradictory, it has been suggested that Si ameliorates Al toxicity by reducing the biological availability of Al. This thesis reveals whether Si could ameliorate Al toxicity at the cell level and investigation of the amelioration mechanism. Mineral analyses were performed in needles of Norway spruce and Douglas fir growing in the Breuil forest, France. Samples were analysed from different positions within the tree, at different locations (fertilised and unfertilised soils) and at two different ages. Results demonstrated that Si did ameliorate the toxic effects of Al in Douglas fir but there was no correlation between Al and Si in the needles of Norway spruce trees. In Douglas fir, the molar ratio of Ca/Al and Mg/Al were shown to be important indicators for Al stress.EThOS - Electronic Theses Online ServiceGBUnited Kingdo