| The shrub wintersweet (Chimonanthus praecox Link) belongs to the Calycanthaceae family, and the plant is native to China. In this paper, the phenotype diversity and floral volatile oil of wild wintersweet were studied. The main results are as follows:1. Wild wintersweets have abundant phenotypic diversities in Wanyuan city. The colors and lengths of mature branches are differeent. The length and width of mature leaves are also significant differences (P＜0.01). The florescences are from early November to late February in next year. The types and colors of flower also have aboundt diversities. Remarkable differences of the floral traits like the size and number of middle-andinner-perianth, the total number of tepals, etc. in different accessions, were discovered (P＜0.01). And, the traits such as flower diameter, size of tepals, number of middle- and inner-perianth, total number of tepals, fresh weight of 100 flowers, angle between pedicel and floral branch, and so on, were significant different (P＜0.01) in 27 randomly selected materials.2. Correlation analysis showed that significant positive or negative correlations between the traits like number and size of tepals, fresh floral weight, angle between pedicel and branch, leave size, etc. of tested wild wintersweets, were observed at 0.05 or 0.01 level. These results established the foundation for selecting wintersweet materials according to trait correlation.3. Many factors affected the essential oil yields of wintersweet flowers. Not only the genotype, but also flowering stage, extraction technology, etc. influenced the essential oil yields. The essential oil yields of flowers from 34 wild wintersweets ranged from 4.4×10-4 to 21.05×10-4, at the average of 12.26×10-4, being much higher than that of cultivate materials (21.05×10-4＞8.70×10-4). Relatively, the oil yield of all tested wintersweets are higher than that of rose (4.4×10-4＞3.0×10-4) by using steam distillation, even two times as more as that of rose by using supercritical CO2 extraction (21.05×10-4＞10.0×10-4). These results implied that excellent genetic resources of wild wintersweets which contain high volatile oil contents established a firm foundation to breed excellent wintersweet varieties containing high essential oil contents. Buds contained higher essential oil yield than full-bloom stage flowers. With the extract time extending, the extraction velocity of volatile oil changed from fast to slow, 95.51% of volatile oil could be extracted during the first 6 hours. And the volatile oil yield reached maximum when solid-liquid ratio becomes 1:5. However, the volatile oil yield varied with tested materials.4. In 27 wild wintersweets, compounds of volatile oil ranged from 30 to 59. 121 compounds were detected by GC-MS, of them, 103 compounds were identified. The volatile oil of cultivate wintersweets contained same compounds as some wild witersweets. The main components of the essential oil were terpenes which occupied 67% of the identified compounds, of which, sesquiterpenes were the most. In 29 tested materials, the relative peak area of identified compounds ranged from 96.452% to 100%. Of which, the range of terpenes were 86.837%～99.428%. Further analysis showed that 11 mutual conpounds were found in the essential oil from 27 wild wintersweets. Of which, elemol was the highest, with average at 13.39%, andβ-cubebene were second with mean at 11.51%. The main compounds were elemol,β-cubebene,γ-elemene,γ-cadinene,β-elemene,γ-muurolene,tau.-cadinol,cadinene and caryophyllene which distributed in tested wild wintersweets over 50%.5. Hierarchical cluster analysis of volatile oil compounds sugested that 29 wintersweets were divided into 5 main categories. The main components of the first category wereγ- cadinene andβ-cubebene. Those of the second category wereβ-cubebene and elemol. Those of the third category wereγ-elemene andβ-cubebene. Material B7 formed the fourth category with the main components of elemol and caryophyllene. And material A17 formed the fifth category with the main components of y-muurolene, elemol andγ-elemene. The compositions from same material in different years and flowering stage were very similar owing to each other being highly clustered.6. Partial correlation analysis of 9 main essential oil compounds of Ch. praecox flowers showed that y-elemene was significantly negatively related with tau.-cadinol at 0.05 level. While cadinene correlated withγ-cadinene and tau.-cadinol at 0.01 level, respectively. Similarly, the significantly positive correlation betweenγ- cadinene and tau.-cadinol also observed.
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