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The Climatic Adaptation of Populations of Cocksfoot (Dactylis glomerata L.) From Southern France

R. Knight
Journal of Applied Ecology
Vol. 10, No. 1 (Apr., 1973), pp. 1-12
DOI: 10.2307/2404710
Stable URL: http://www.jstor.org/stable/2404710
Page Count: 12
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Climatic Adaptation of Populations of Cocksfoot (Dactylis glomerata L.) From Southern France
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Abstract

Populations of Dactylis glomerata were sampled along two transects in southern France both of which began near the Mediterranean coast, one going 80 km north to the Massif Central, the other 450 km west to the Atlantic seaboard. These populations and a group of ecotypes and cultivars were grown in the Mediterranean-type climate of Adelaide, Australia. Seasonal yields, summer survival, heading dates and head numbers were assessed over two years. These assessments were related to the climatic conditions prevailing at the respective collecting sites. The ombrothermic relation was used to provide an estimate of summer drought. There was variation in seedling vigour with populations from dry Mediterranean environments in particular, lacking vigour. At the first harvest there was more than a twenty-fold variation in yield. Both transects covered the range from summer-dormant to summer-growing populations a variation that was related to the duration of the drought period and not to annual rainfall. The ability of a population to survive the summer was inversely correlated with its summer growth. Winter dormancy was detected only in high-altitude populations from the Massif Central. Although a wide variation in heading dates was obtained it could not be related to position in the transect and macro-climatic factors, but must have been due to microclimatic or biotic factors. Populations from near the Mediterranean produced the greatest number of heads. Seed retention was highest in populations that were summer-dormant, and these produced many naked seeds when threshed, whereas the summer-growing populations readily shed seed when ripe, the seed being enclosed by glumes.

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