Abstract: The random amplified polymorphic DNA marker (RAPD) was assessed to detect the genetic relationships among 18 Cymbidium hybridum cultivars from 2 companies. The results showed that primers were screened from 50 random decamer primers, and a total of 92 DNA bands were amplified, 90 of which (97.8%) were polymorphic. The average number of polymorphic DNA bands amplified by each primer was 6. Genetic similarities among the cultivars ranged from 0.1975 to 0.6704 with an average value of 0.4761, and the genetic distance among those ranged from 0.3296 to 0.8025 with an average value of 0.5239. A dendrogram of genetic relationship which was constructed using UPGMA method showed that all the tested cultivars were classified into 4 cluster groups with the genetic distance coefficient of 0.5239. It revealed that the genetic relationships among tested cultivars were related with flower color and branch type to some extent.

Key words: Cymbidium hybridum, genetic relationship, RAPD technique