Research progress of Hydrangea breeding

Hydrangea macrophylla is an important ornamental plant in developed countries. It can be used as potted plants，nursery stocks，cut flowers etc.，and plays a significant role in the market. There are more than 600 varieties of Hydrangea. The Hydrangea association，related cultivation standard systems and new varieties of testing techniques have been established abroad. China as the germplasm resource center of Hydrangea，there are most of original species of Hydrangeas used for crossbreeding originated in China. However，there are serious shortages in breeding work in China compared with foreign countries，which are insufficient development of Hydrangea germplasm resources，backward breeding technology and so on. Therefore，this article reviewed the germplasm resources and classification of Hydrangea in China and abroad，the relevant institutions and the status of breeding at home and abroad，the main cultivars and application status. At the same time，the existing problems，breeding methods， and breeding trends，such as flower type，color，and resistance，are summarized，so as to provide reference for Hydrangea breeding and cultivation in China.