Aluminum sensitivity and optimum Ca and pH requirement of teak (Tectona grandis Linn, f.) clones used for forestry plantations in Australia

摘要

Teak is adapted to grow in tropical and subtropical regions and is considered to require fertile soils. Despite this, teak is often planted in soils that are highly leached, acidic and potentially Al-toxic. In Australia, several clones are commonly used for teak plantations and the aim of this study was to determine the optimum pH, Ca requirement and Al sensitivity of these clones. Biomass increase of nutrient solution-grown teak plants was used to determine the optimum pH and Ca. There were no significant differences in optimum pH and Ca between clones and, overall, the greatest growth was obtained with nutrient solutions containing 1 mM Ca and adjusted to pH 6. Teak plants still grew at pH 4, but developed foliar Ca deficiency symptoms at 0.1 mM Ca. The Al sensitivity was determined by staining excised roots with chromeazurol S, eriochrome R and hematoxylin. Roots of plants exposed to 50 and 300 muM Al for 1-7 days gave a strong reaction with hematoxylin, and chromeazurol S, but a weak response to eriochrome cyanine R. The greatest resistance to low pH and Al was observed in the two clones E and H.