STUDIES ON THE TOLERANCE TO SO2 OF GRASS POPULATIONS IN POLLUTED AREAS

III. INVESTIGATIONS ON THE RATE OF DEVELOPMENT OF TOLERANCE

Authors

  • G. B. WILSON,

    1. Department of Pure and Applied Biology, Imperial College at Silwood Park, Ascot, Berkshire SL5 7PY, UK
    Search for more papers by this author
    • *

      Department of Physiology and Environmental Science, University of Nottingham, School of Agriculture, Sutton Bonington, Loughborough, Leicester LE12 5RD, UK.

  • J. N. B. BELL

    Corresponding author
    1. Department of Pure and Applied Biology, Imperial College at Silwood Park, Ascot, Berkshire SL5 7PY, UK
    Search for more papers by this author

To whom all correspondence should be addressed.

Summary

The development of acute and chronic sulphur dioxide (SO2) tolerance in lawn grass populations was studied by two approaches: the minimum time for tolerance to appear in Festuca rubra L., Lolium multiflorum Lam., L. perenne L., Phleum pratense L. and Poa pratensis L., was determined by comparison annually of plant samples from monoculture plots sown at a polluted site, with plants grown from the seed originally sown; the long term development of tolerance in F. rubra, D. glomerata L. and Agrostis tenuis Sibth. was also investigated by comparison of five lawns of different ages (1–c. 200 years) at a polluted site.

Tolerance to acute SO2 injury was detected in L. perenne and Phleum pratense only three and four years after sowing, respectively. However, population samples of these two species, collected from the field three years later, showed no significant SO2 tolerance. An analysis using morphological and isozyme variation as criteria showed that the tolerant population consisted of a large number of different individual genotypes. The populations experienced a state of evolutionary flux with rapid selection first of the tolerant, and subsequently of the non-tolerant phenotypes. The disappearance of tolerance coincided with declining ambient SO2 concentrations.

The lawns of different ages were shown to represent an evolutionary series of increasing acute SO2 tolerance with age of lawn in F. rubra and A. tenuis. This demonstrated the continuing development of acute SO2 tolerance in grass populations over a prolonged period.

The significance of the occurrence and rate of development of SO2 tolerance for grasslands in polluted areas is discussed.

Ancillary