Azalea is one of the most popular ornamental plants in China. On the production of pot azaleas, heating strategy is widely used to force flowering, so the products can meet the needs of Spring Festival market in China. This study was conducted to find another possible way to break flower bud dormancy and promote anthesis through environment friendly ways. Fouryear-old azalea 'Hong Shanhu' (Chinese azalea cultivar) were sprayed with different combinations of 5-azacytidine (2.5, 10, 40 and 160 mg L-1) and gibberellic acid (300 mg L-1). These were kept in greenhouse during the winter with no extra heating device. Morphological changes, endogenous hormones, and the degree of DNA methylation were recorded. The results showed that the combination of 40 mg L-1 5-azaC and 300 mg L-1 GA3 can highly promote flower bud growth and brought anthesis 17 days earlier than controls. IAA content increased about twofold (control and T1) and fivefold (T4) after growing for four months. A steep decrease of DNA methylation was observed from November to February and followed by an increase until flowering in all treatments. The foliar application of these chemicals was found to be more effective on bud dormancy breaking by DNA demethylation and decrease of ABA levels.

Evergreen azaleas are among the most important ornamental shrubs in China. Today, there are probably over 300 cultivars preserved in different nurseries, but with little information available on the cultivar itself or relationships between cultivars. Amplified fragment length polymorphism (AFLP) markers were employed to determine the genetic relationships between evergreen azalea cultivars in China. One hundred and thirty genotypes collected from gardens and nurseries, including cultivars classified in the groups East, West, Hairy, and Summer, unknown cultivars, and close species, were analyzed using three primer pairs. A total of 408 polymorphic fragments were generated by AFLP reactions with an average of 136 fragments per primer pair. The average values of expected heterozygosity and Shannon's information index were 0.3395 and 0.5153, respectively. Genetic similarities were generated based on Dice coefficients, used to construct a neighbor joining tree, and bootstrapped for 100 replicates in Treecon V1.3b. Principal coordinate analysis (PCO) was performed based on Dice distances using NTSYS-pc software. The AFLP technique was useful for analyzing genetic diversity in evergreen azaleas. Cluster analysis revealed that cultivars in the West and Summer groups were quite distinct from other groups in the four-group classification system and that the East and Hairy groups should be redefined.