Genetic diversity and relationships among commercial sugarcane varieties in Thailand

Objective of this study was conducted to determine the diversity and relationships among commercial sugarcane varieties in Thailand. The pedigree in each variety was traced back to the original ancestors. The coefficient of parentage was calculated from records of 70 varieties, and a dendrogram was drawn using the unweighted pair-group method using arithmetic averages (UPGMA) of clustering. Pedigree data showed that Thai commercial varieties were only bred from 26 exotic varieties. The analytical results indicated that many sugarcane varieties had higher close relationship with OCSB3 (37.3%) than UT1 (20.4%). S. officinarum was major genetic contributor (25.1%) whereas S. barberi, S. spontaneum, and S. sinense were 10.8, 5.9, and 2.4%, respectively. These revealed that the Thai improved sugarcane varieties have narrow genetic base. Thus breeders should introduce novel germplasm into sugarcane breeding programs in the futur