Abstract
For breeding of high-yield and high-quality cultivars of Amacha (sweet Hydrangea) and establishing the culture system, the characteristics of Amacha varieties were studied in comparison with other Hydrangea. Twenty five varieties of Hydrangea including four Amacha varieties, including Hydrangea macrophylla Seringe var.thunbergii Makino and Hydrangea macrophylla Seringe var.amagiana Makino, were used. Several agronomic traits, total DNA amount determined by flow-cytometry, the number of chromosomes and SSR markers were investigated and principle component analysis was performed. The results showed that Amacha varieties were similar to other Hydrangea varieties and could not be distinguished from the other varieties. However, there were differences even among Amacha varieties in chromosome number, leaf number and suitable light intensity. This suggests that it is possible to develop new high yielding and high quality cultivars by crossing among Amacha varieties or between Amacha varieties and other Hydrangea varieties and by polyploidy breeding.
