Physiological differences among populations of Anthoxanthum odoratum L. collected from the Park Grass Experiment, Rothamsted. 2. Response to aluminium.
Populations of A. odoratum collected both from unlimed plots of the Park Grass experiment and from natural acid soils were more tolerant of high Al concentrations than were those from limed Park Grass plots and natural calcareous soils. The response of each population to Al was closely correlated (r = 0.95) with the soil pH of its source site. The differences in response to Al between populations of A. odoratum collected from the Park Grass Experiment, which have evolved within 65 years, and over distances of <30 m, were as large as the differences between natural populations from equivalent soil types. The response of each population to Al, measured in terms of root elongation of individual tillers, when grown for 6 or 9 days in complete culture solution with or without added P, was closely correlated (r = 0.96) with the response to Al measured in terms of DM yield, when grown for 5 months in complete culture solution in sand culture. Response to Al, measured in terms of root elongation in calcium nitrate solution, was not significantly correlated (r = 0.38) with response to Al measured in terms of DM yield in sand culture. It was concluded that the root elongation technique, using complete culture solution, was a rapid and satisfactory method of evaluating response to Al in A. odoratum, but that results obtained using calcium nitrate solution were not a reliable measure of Al response in this species.