DIFFERENTIAL RESPONSE TO CALCIUM WITHIN THE SPECIES FESTUCA OVINA L.

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Abstract
Summary: An investigation of population differentiation within the species Fcstuca ovina in relation to soil factors has shown that populations within this species differ greatly in their response to calcium in culture solution. Populations from acid, low calcium soils showed a weak response to calcium, whilst those from calcareous soils showed a strong response. All populations responded linearly to the logarithm of the calcium concentration at the low levels, but there was a decrease in yield of the acidic populations at higher calcium levels. The difference in response to calcium between the acidic and calcareous types of populations was as great as that previously shown to exist between extreme calcicole and calcifuges species. Such differences were found even between populations taken from areas only about I mile apart.Smaller scale variation was also shown to exist between individuals within single populations.Chemical analysis of the plants indicated that the differences in response between populations were due to differences in ability to absorb calcium from low solution concentrations, rather than to differences in ability to metabolize at low internal concentrations of calcium. The populations were also found to differ in ability to absorb other cations and in ability to root at low levels of calcium.The evolutionary significance of the results is discussed, and the importance of recognizing such variability, within apparently homogeneous species, in ecological and physiological studies is stressed.