The growth of cocksfoot (Dactylis glomerata L.) under spaced plant and sward conditions

The cumulative growth of nine clones of Dactylis glomerata was compared under two conditions of spacing. The first spacing was chosen to provide conditions similar to those of a breeding nursery, the second, conditions met with in swards. Data were obtained for two growing seasons, the individual plant and its parts being considered at each harvest. Of the nine clones seven were developed from plants obtained from the Mediterranean region and two from Great Britain. There was a poor correlation between plants under the two spacing conditions, particularly as later in the life of the swards clones reacted differently to competition. Competition did not lead to a uniformity of top weight for the clones in the swards. These results are discussed in relation to the conflicting results of similar studies and the reaction of genotypes to factors of the environment affecting growth. It is suggested that plants in the vegetative phase are affected by competition differently from plants in the reproductive phase. Some clones were found to regenerate after summer dormancy more rapidly than others, but initial advantages were not maintained. The relative development of parts of the plants differed between clones, some having high proportions of their total weight below ground. At the time of reproduction, despite very large differences in total weight between plants of a clone under the two spacing conditions, the percentages of plant parts were very similar. A high mortality was shown during the summer by the two clones from northern European plants, but only a negligible mortality by the Mediterranean plants.