Volatile organic compound emissions from different stages of Cananga odorata flower development

Abstract

Headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to identify the volatile organic compounds (VOCs) of the different flower development stages of Cananga odorata for the evaluation of floral volatile polymorphism as a basis to determine the best time of harvest. Electronic nose results, coupled with discriminant factor analysis, suggested that emitted odors varied in different C. odorata flower development stages, including the bud, display-petal, initial-flowering, full-flowering, end-flowering, wilted-flower, and dried flower stages. The first two discriminant factors explained 97.52% of total system variance. Ninety-two compounds were detected over the flower life, and the mean Bray-Curtis similarity value was 52.45% among different flower development stages. A high level of volatile polymorphism was observed during flower development. The VOCs were largely grouped as hydrocarbons, esters, alcohols, aldehydes, phenols, acids, ketones, and ethers, and the main compound was β-caryophyllene (15.05%-33.30%). Other identified compounds were β-cubebene, D-germacrene, benzyl benzoate, and α-cubebene. Moreover, large numbers of VOCs were detected at intermediate times of flower development, and more hydrocarbons, esters, and alcohols were identified in the full-flowering stage. The full-flowering stage may be the most suitable period for C. odorata flower harvest.

Figure 1

The morphological characteristics of C. odorata flower in seven different stages. (I) bud stage; (II) display-petal stage; (III) initial-flowering stage; (IV) full-flowering stage; (V) end-flowering stage; (VI) wilted-flower stage; and (VII) dried flower stage.

Figure 2

Two-dimensional (2D) DFA plots of flower from different stages by electronic nose. (I) bud stage; (II) display-petal stage; (III) initial-flowering stage; (IV) full-flowering stage; (V) end-flowering stage; (VI) wilted-flower stage; and (VII) dried flower stage.

Figure 3

The composition of volatile compounds in different stages of C. odorata flower development by HS-SPME-GC-MS. (I) bud stage; (II) display-petal stage; (III) initial-flowering stage; (IV) full-flowering stage; (V) end-flowering stage; (VI) wilted-flower stage; and (VII) dried flower stage.

Figure 4

Principal components analysis biplot showing relationship between the different stages of C. odorata flower development and the volatile compounds: PC1 vs. PC2 plots (a) and PC 1 vs. PC 3 plots (b). (I) bud stage, (II) display-petal stage, (III) initial-flowering stage, (IV) full-flowering stage, (V) end-flowering stage, (VI) wilted-flower stage, and (VII) dried flower stage. Black dots represent distribution of 92 volatile compounds in C. odorata flower (numbers correspond to those in Table 1).