RESPONSES OF 5 SPECIES OF CONIFER SEEDLINGS TO ALUMINUM STRESS

Seedlings of red, white and black spruce, and white and jack pine were tested for their response to a range of Al concentrations, when grown for 12 to 14 weeks in sand culture in the greenhouse. Nutrients were supplied in solution of pH 3. 8 to which Al was supplied at 0, 5, 10, 20, 40, 80, and 160 mg/L. Red and white spruce were inhibited in growth from 5 mg/L upwards, while black spruce was equally inhibited only at concentrations greater than 20 mg/L. In contrast, white pine was stimulated by 5 to 20 mg Al/L and was always more tolerant than the other 4 species at every Al level used. Jack pine was intermediate in its response. There was a positive linear relationship between P and Al accumulation in the shoots of red spruce. This was in contrast to the other 4 species in which P concentrations in the shoot decreased with an increase in Al concentrations.