Root growth and heavy metal uptake by three graminaceous plants in differentially limed layers of an acid, minespoil-contaminated soil

Abstract

Plants of three cereal genotypes were grown in pots of an acid, minespoil-affected soil containing high amounts of zinc, copper, lead and sulphur. The soil was differentially limed, in two layers each 20 cm deep, to give all possible combinations of four rates of application. Such a layering of toxic and limed soil is likely to occur during attempts to ameliorate the soil in situ. Lime treatments in either layer improved plant growth and reduced zinc content, but the treatment in the upper layer had the greater effect. Barleyy (cv. Abyssinian), the most sensitive genotype, only just survived in the unlimed soil and, even when the upper layer was limed, its roots could not penetrate an unlimed lower layer. Rye (cv. Strain 8) was the most tolerant genotype, but accumulated high concentrations of zinc. Oats (cv. Algerian) was reasonably tolerant of the toxicity, and was able partially to exclude heavy metals from its leaves, so that their yield in the herbage was less than in the other two species.