Aroma components of different flower organs of two Dendrobium Sw. varieties

【Objective】 This paper compared differences in floral components and its main aroma components in two Dendrobium Sw. varieties, in order to provide scientific foundation for cultivating new varieties of fragrant Dendrobium Sw.【Method】 D. parishii with strong fragrance and Dendrobium Zhenzhu with light fragrance were selected as research objects, headspace solid phase microextraction combined with gas chromatography-mass spectrometry(HS-SPME-GCMS) was utilized to analyze the types and relative content of aroma components in different flower organs(sepals, lips, petals, and gynostemium).【Result】 A total of 96 volatile components in 7 categories were detected, with only 4 components in common(1-hexanol, 4, 7-dimethyl-4-octanol, trans-2-octen-1-ol and hexanal) between the 2 varieties. A total of 37 volatile compounds were detected in 4 different flower organs of D. parishii, including 11 aldehydes, 8 ketones, 5 alkenes, 4 alcohols, 4 esters, 2 alkanes and 3 other compounds, with 14 shared components. The main components of sepals were hexanal(28.09%), trans-2-nonenal(14.00%) and 2-pentadecanone(13.66%), while the main components of petals were hexanal(24.50%), trans-2-octenal(13.23%) and 2-pentylfuran(12.69%). The main components of the lips were 2-pentadecanone(29.04%), 2-tridecanone(12.71%) and hexanal(10.48%). The main components of gynostemium were the same as those of the lips, but the contents were different. The relative contents of 2-pentadecanone, hexanal and trans-2-nonenal were high, indicated strong fragrance. A total of 63 volatile compounds were detected in 4 different flower organs of Dendrobium Zhenzhu, including 26 olefins, 15 alcohols, 7 esters, 3 alkanes, 4 ketones, 2 aldehydes and 6 other compounds, with 11 shared components. Among them, the olefins presented the highest relative content, which mainly in D-limonene, γ-terpinene, caryophyllene and β-myrcene, formed a clear and sweet aroma. The major components in petals were D-limonene(20.04%), 1-hexanol(12.56%) and caryophyllene(10.93%);those in sepals were D-limonene(40.60%), β-myrcene(7.81%) and 3-carene(7.63%);those in lips were D-limonene(22.92%), 1, 3, 3-trimethyl-tricyclo2.2.1.0(2, 6) heptane(18.99%) and(Z)-3, 7-dimethyl-1, 3, 6-octadecane triene (10.92%);those in gynostemium column were D-limonene(48.59%), α-pinene(12.62%) and β-myrcene(11.75%).【Conclusion】 There are great differences in the number and relative content of volatile components between D. parishii and Dendrobium Zhenzhu, and the composition of aroma components is complex;2-pentadecanone is the main aroma component in the floral organs of D. parishii, and D-limonene is the main aroma component in the floral organs of Dendrobium Zhenzhu.