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

Abstract

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.

The effects of nutrient limitation on the response of Plantago major to ozone

“…Thus there is a penalty, or physiological cost, associated with heavymetal tolerance. There is also evidence that some form of cost is associated with resistance to SO # (Wilson & Bell, 1985 ;Bell, Ashmore & Wilson, 1991). The temporal variation that is characteristic of ozone pollution increases the importance of the relative performance of resistant and sensitive genotypes in both polluted and non-polluted environments (Roose, Bradshaw & Roberts, 1982 ;Pitelka, 1988).…”

The response of native, herbaceous species to ozone: growth and fluorescence screening

“…This raises the possibility that there has been selection in favour of resistance. There is evidence that O3 has led to selection in some tree species (Berrang et aL, 1986;Scholz, 1986) but the evidence is stronger for other air pollutants especially SO^ (Taylor & Murdy, 1975;Horseman, Roberts & Bradshaw, 1978;Wilson & Bell, 1985;W'ilson & Bell, 1990). As selection would decrease the impact of Oy it is important to determine the kind of O3 climate that might lead to selection, and the speed of population response.…”

Adaptation of grasses in the Netherlands to air pollution

“…capillaris tor evolution of tolerance to a number of environmental pollutants (I':rnst, 1974;Dueck et al, 1984;Wilson & Bell, 1985), .V. stricta appears to be less able to achieve tolerance, although the growth results of the Budel population indicate a significant growth increase following exposure to SO,, dioxide and NH3.…”

“…The evolution of tolerance to acute injury by sulphur dioxide is a more rapid process than resistance to chronic injury (Wilson & Bell, 1986), the former taking place within 3-5 years (Wilson & Bell, 1985) and the latter within 17-25 years (Ayazloo & Bell, 1981). In view of the data presented here, resistance to chronic injury in A. capillaris may be present (Tables 2 and 3), but certainly not to acute injury (Table 4).…”