THE PERFORMANCE OF AGROSTIS CAPILLARIS L. GENOTYPES, DIFFERING IN COPPER TOLERANCE, IN RYEGRASS SWARDS ON NORMAL SOIL

Sample sub-populations, each of six plants, were chosen for high, mid and low tolerance of copper from each of two naturally-occurring copper tolerant populations and from tolerant individuals selected from a cultivar of Agrostis capillaris L. The naturally-occurring ecotypes came from a closed sward community at Drws y Coed, and from an open community at Parys Mountain, both copper mines in North Wales. Clonal replicates of all plants were introduced into swards of perennial ryegrass cvs. S23 or S24, growing on normal soil at the University of Liverpool Botanic Gardens. S23 plots were cut eight times between June 1977 and July 1978, whilst S24 plots were cut 3 times during the same period. Half the experimental plots received N, P, K, fertilizer; the rest received none. Plants selected from the cultivar (selected) produced most dry matter, and with infrequent defoliation flowered freely in competition with ryegrass. Those taken from Parys Mountain mine spoil produced least dry matter and no inflorescences. Drws y Coed plants were intermediate in dry matter and inflorescence production. These results may reflect differences in population density in the habitats from which the populations were sampled. Sub-populations chosen for high, mid or low copper tolerance within the selected and Drws y Coed populations did not differ significantly in dry matter yield. By contrast under certain circumstances Parys Mountain plants with low tolerance outyielded other more tolerant plants. These results are considered with respect to growth strategies adopted by plants growing on and off copper mine sites.