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Most electricity pylons are zinc coated. It might be possible for this to cause zinc contamination of soil beneath the pylons sufficient to impose selective forces by which zinc-tolerant populations would develop in a replicated manner. An investigation of Agrostis capillaris L. populations sampled under a series of pylons in North Wales shows that: (1) Zinc concentrations are considerably greater in soils beneath pylons, particularly adjacent to pylon legs. (2) Soils sampled under different pylons had mean zinc concentration varying from 1250±200 to 6500±4000 μg g-1 as total, and from 570±188 to 3000±2000 μg-1 as acetic acid extractable. In control soils, comparable values were from 170±35 to 320±90 μg-1 total zinc, and 70±10 to 140±30 μg g-1 acetic acid-extractable zinc. (3) Zinc toxicity is found in such soils causing significant reduction in plant dry weight and tiller production of normal material of A. capillaris. (4) The pattern of root growth response to increasing zinc concentration in solution culture of samples of adult plants collected from beneath pylons differed significantly. (5) Some individuals had zinc tolerance equivalent to that of zinc mine plants; others had how but measurable tolerance; others differed little from plants from uncontaminated control sites. These results clearly show that evolution of zinc tolerance has occurred rapidly, since the pylons sampled were all less than 30 years old, but the outcome is different under different pylons, almost certainly because of differing genetic constitutions of different founding populations. [ABSTRACT FROM AUTHOR]

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]