'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 GENETIC VARIATION FOR SEED PRODUCTION IN COCKSFOOT (DACTYLIS GLOMERATA L.) ACCESSIONCES GROWN AS SPACED PLANTS A.A. JAFARI Research Institute of Forest and Rangelands, PO Box 13185-116, Tehran, Iran

In order to study the genetic variation for seed yield and its components among Foreign and Domestic accessions of cocksfoot (Dactylis glomerata L.), an experiment was conducted in Alborz Research Centre, Karaj, Iran. Thirty-two accessions were evaluated under spaced plant condition for plant girth, heading date, antithesis date, disease reaction, plant height, fertile tiller number, seed yield per plant, seed yield per panicle, panicle length, thousand grain weight, seed number per panicle, forage dry matter yield and harvest index. Principal component analyses were used to group the cocksfoot accessions. Analysis of variance showed significant differences accessions for all traits. The Iranian accessions namely: 1761. 10505 and 412 had the highest seed yield per plant over two cuts. Accessions 1769 and 1261 originated from Netherlands and USA respectively had the highest forage dry matter production. Using principal component analysis, the most important variables for seed yield characters were identified. First three independent components accounted for 78% of total variation. The first principal component indicates that heading date, seed yield and harvest index were important characters for classification. Forage dry matter yield, plant height and stem number were important characters in the second component. Based on multivariate analysis, 32 entries were divided nto6 groups. Accessions in cluster 2 and 3 averaged well above the overall mean for forage dry matter and seed yields respectively. Majority of accessions in cluster 2 was originated from European countries, whereas accessions in cluster 3 were originated from different parts of Iran. Accessions from a defined geographic are tend to cluster but some accessions from a particular area spread among several cluster.