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

Populations of Dactylis glomerata were sampled at points along two transects in southern France and a study made of the variation in plant characters associated with variation in the environment along the transect. D. glomerata is a perennial cross-pollinated grass with a natural distribution that includes parts of Europe, North Africa and Asia (Stebbins 1956). Within this range are some ecotypes which grow in summer and are dormant in winter and others which grow in winter and are dormant in summer (Knight 1960, 1962, 1966). The winter-dormant ecotypes are indigenous to regions with cold winters, mainly at high latitude, while the summer-dormant ecotypes are indigenous to Mediterranean type climates with hot, dry summers. In many parts of its natural distribution, the range from winter-growing to summer-growing ecotypes, may occur over a short distance. The present study is concerned with two examples of such situations in southern France. Transects were chosen where detailed climatic data were available for the areas in which they occurred and because the climate in parts of the transects resembles that of southern Australia where the collections were studied. Every effort was made to sample only wild populations as they are expected to reflect the indigenous environment more precisely than cultivars of the species being grown in local agriculture. D. glomerata was first introduced to Australia more than 150 years ago from temperate parts of Europe but it has been only in the last 30 years that introductions have been made from the Mediterranean region. As with many other pasture plants from this region there is still a great potential for domestication of wild populations and their use as cultivars after a minimum of selection. To formulate rational programmes of plant introduction it is essential to know the relation between the environment in which populations evolved and their subsequent performance as pastures in Australia.