# Comparative Analysis of Volatile Compounds in Flowers of Different _Actinidia_ Species
## 2 Results and Discussion
### Differences in the Composition of Volatile Compounds in Flowers of Different Actinidia Species  
In our research, much of the _A. chinensis_ var. _deliciousa_ headspace samples were straight-chain hydrocarbons. None of these were found in other tested species (Table 1). Two of these, 9-octadecene (E) and pentadecane, were identified as the main compounds and accounted for 31.8 and 19.6%, respectively (Figure 2a), of the total. These two compounds were previously identified in _A. chinensis_. 9-octadecene (E) was found in _A. chinensis_ var. _deliciousa_ cultivars, yet in a much smaller percentage (0.03-0.13%) [22]. As in previous research, a similar level of pentadecane was found in _A. chinensis_ var. _chinensis_ var. _chinensis_ and in _A. chinensis_ var. _deliciousa_ (9-20%, depending on the cultivar) [20; 22]. 5-dodecen-1-ol, acetate, (Z)- (19.9%) and phenylethyll alcohol (9.2%) represented other important compounds. The latter (phenylethyll alcohol) was also found in _A. arguta_ male (0.2-12.2%) and female (5.3-25.0%) flowers. A few more aromatic straight-chain hydrocarbons--heptadecane (3.0%), hexadecane (1.8%), and nonadecane (0.7%)--were also found in the _A. chinensis_ headspace. Finally, 2-phenethyl acetate (0.4%), and benzoic compound--1,3-dimethylbenzene (0.4%) were identified in the _A. chinensis_ var. _deliciousa_ sample. _A. chinensis_ var. _deliciousa_ headspace was characterised by the presence of a few terpen. These were: alpha-Farnesene, cocimene, cis-Geranylacetone and D-limonene (the one with a well-known lemon-like odour). Their content in headspace amounted to 5.0, 1.2, 0.4 and 0.4%, respectively. D-limonene was also found previously in _A. chinensis_ flowers [20; 21]. Comparison to previous research on both _A. chinensis_ varieties indicated that the particular genotypes differed in the number of identified compounds, composition and amount [17; 18; 20; 21; 22]. Five of the compounds identified by [PERSON] et al. [18] in _A. chinensis_ var. _deliciousa_, namely alpha-Farnesene, hexadecane, cis-geranylacetone, nonadecane and phenylethyll alcohol, were also found in our research. Similar compounds such as those in our research, namely terpen (D-limonene, cocimene, alpha-Farnesene), straight-chain hydrocarbons (pentadecane) and alcohols, like phenylethyll alcohol, were found by [PERSON] et al. [20]. Among the 27 compounds identified by [PERSON], [PERSON] and [PERSON] [21] in _A. chinensis_, only three (limonene, ocimene and alpha-Farnesene) were identical to the ones in our research. The following compounds were found in our and previous research in _A. chinensis_  
Figure 2: Sample chromatograms with main volatile compounds in male flowers of four actinidia species: (**a**) _Actinidia chinensis_ var. _deliciousa_; (**b**) _Actinidia polygamma_; (**c**) _Actinidia kolomika_; (**d**) _Actinidia arguta_. var. _deliciosa_ flowers: tridcane, nonadecane, pentadecane, hexadecane, 7-hexadecene, heptadecane, alpha-Farnesene, 2-phenylethyll acetate, phenylethyl alcohol and cis-geranylacetone. However, the latter compound was found in one of the six genotypes of _A. chinensis_ var. _deliciosa_[22]. Alpha-Farnesene was the one compound found in all available results; however, its percentage of all the identified compounds stood between 0.6 and 38.0%, depending on the information source [17; 18; 20; 21; 22]. No linalool and lilac compounds characteristic of _A. arguta_ were found in _A. chinensis_[23; 25]. When analysing the _A. polygamma_ flower aroma in detail, it was found that some compounds were characteristic of that species only. These included, e.g., 2-hexenal (6.6%) and 2-hexen-1-ol, (E)- (17.5%) (a primary allylic alcohol, used for food flavouring, PubChem). Form (Z)- was also found, but in a much smaller amount (0.2%). However, linalool (47.8%) (Figure 2b), the major compound of _A. polygamma_ volatiles, was also discovered in eight out of eleven _A. arguta_ samples. Beta-citronellol (13.2%) was another important compound of _A. polygamma_ also found in _A.