| Abstract: | Summary. Early development of Cynodon dactylon (L.) Pers, was studied on one-node rhizome fragments planted at successive dates over a year. Aerial growth followed the changes in external temperature; in the cool season tops grew very slowly but remained alive. New rhizomes were formed only at temperatures exceeding 15–20°C. Flowering occurred in the warm season from May onwards. No relationship was found between flowering and rhizome formation. The age of plants forming new rhizomes decreased from 5 months for the January planting to less than 2 months for the May-September plantings. Rhizome bud germination was maximal between 23 and 35°C, slow below 20°C and inhibited at 10°C. The weight ratio of tops to subterranean parts of established plants was near 1 in winter, declined in March-April and remained at 0·5–0·6 from May onwards. An established sward of C. dactylon was sampled from September to November of the following year. Dry weight was lowest from January to mid-April, rose in spring and decreased in late summer. Almost no rhizomes were found deeper than 45 cm. Underground parts from the 0–15, 15–30 and 30–45 cm horizons constituted 62, 26 and 12% of the total weight, respectively; rhizomes formed more than 90% of the total underground dry weight. In the warm season the dry weight of the subterranean organs amounted to 2, 0·7 and 0·4 kg/m3 of soil in the three horizons, respectively. Percent dry matter in tops and subterranean parts was about 35–45% in the winter and 50–65% in the warm season. Up to 2% reducing sugars was found in various parts of the plants. The water-soluble sugar content of rhizomes was high in November-December, decreased in late winter, rose again in spring, and decreased in late summer. Percent germination of rhizome buds fluctuated greatly during the year, but complete dormancy was never recorded. Newly-formed rhizomes showed a high germinative capacity. Similar germination percentages were found on fragments with one node and those with several nodes. Développement du Cynodon dactylon (L.) Pers. |
