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Samples of 15 000 seeds from each of nine populations of Agrostis capillaris L. were screened for ability to root in solution cultures containing cadmium, copper, lead, nickel, and zinc at levels which severely inhibited root growth in non-metal-tolerant seed population samples. Differences were found in the extent to which tolerant individuals could be selected from the populations. Only the copper-tolerant cv. Parys and lead-/zinc-tolerant cv. Goginan had relatively high frequencies of individuals tolerant to each metal. Screening one population did not reveal any tolerant individuals. The ability to root in such solutions may reflect the potential populations have to evolve metal-tolerant populations. Populations exhibit considerable variation in this respect and the potential to evolve tolerance is clearly a characteristic of populations, not the species. [ABSTRACT FROM AUTHOR]

Root growth of seedlings of the Agrostis capillaris L. cultvars Parys (copper tolerant), Goginan (lead/zinc tolerant), and Highland (non tolerant) was measured after 14 d growth in solution cultures with increasing concentrations of Cd, Cu, Pb, Ni and Zn. Increasing inhibition of root growth of all three cultivars occurred with increasing concentrations of all five metals, Highland being most affected. In Cu, Parys was least affected; in Pb and Zn Goginan was least affected. Parys and Goginan thus display specific resistance to these metals. They are also similar in having greater root lengths at higher metal concentrations of all five metals than Highland. They thus exhibit non-specific low level tolerance to metals other than those present at toxic levels in the soils from which they were derived. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The rooting response of seven populations of Agrostis tenuis Sibth. to a range of copper concentrations in calcium nitrate solution is described. Variation in both index of tolerance and sensitivity of rooting to increased copper levels were found and shown to be phenotypically independent characters. It is suggested that rooting sensitivity to a range of copper concentrations provides a further measure of copper tolerance which is independent of the methods previously employed for assessing tolerance. [ABSTRACT FROM AUTHOR]