## 3 Discussion
Alkenes, alcohols, and alkanes were the three major types of volatile components, but few alkynes were detected, which contrasted with the research results described above. In addition, some researchers discovered that in the cold-resistant water lily, the main aroma components were alcohols, aldehydes, and ketones, and the most abundant substances were pentadecane, 8-heptadecene, 6,9-heptadecadiene, tridecane, and tetradecane. In the tropical water lily, the main aromatic substances were esters, alcohols, terpen, aldehydes, and ketones, with high contents of 6,9-heptadecadiene, pentadecane, 8-heptadecadiene, farnesene, and Z,Z-10,12-hexadecadien. There are obvious differences in the aromas of the two ecotypes of water liliies [29]. The flower aroma of the cold-resistant water lily is influenced by nerolidol and lilac alcohols, with orange and clove flower aromas, while the aroma of tropical water lities is influenced by ethyl benzoate, acetic acid phenylmethyl ester, and 2-heptadecanone, which provide a fruity and sweet flower aroma [54]. _N. hybrid_ is a tropical water lily. By summarizing and comparing the main volatile components in \(N\). _hybrid_ with the previously studied _Nymphaea_ spp. (Table 4) [55; 56; 52; 53], we found the contents of benzyl alcohol, pentadecane, (E)-\(\beta\)-famesene, (6E,9E)-6,9-heptadecadiene, and 8-heptadecadiene in different strains of \(N\). _hybrid_ were high, which is similar to the main volatile substances found in other tropical water lities. However, the differences were that in \(N\). _hybrid_, it also contains relatively high levels of benzyl alcohol, benzaldehyde, trans-\(\alpha\)-bergamotene, \(\alpha\)-sesquiphellandrene, \(\alpha\)-curcumene, and \(\alpha\)-bisabolene. Previous studies on volatile compounds are often focused on terpenes [2; 49; 57] and in our study a few monoterenes (terpinen-4-ol, (-)-verbenone, \(\alpha\)-ionone, (E)-\(\alpha\)-atlantone, and D-limonene) and several sesquiterpenes, mainly trans-\(\alpha\)-bergamotene, \(\alpha\)-sesquiphellandrene, (E)-\(\beta\)-farmesene, and \(\alpha\)-bisabolene, were found in \(N\). _hybrid_. Terpenes are well known for their contribution to pleasant sensory notes, such as herbaceous, fruity, citrus, and floral scents [58]. All these volatiles compounds may give \(N\). _hybrid_ a sweeter fruity floral scent than other water lities. The unique scent of \(N\). _hybrid_ may attract pollinators such as _Bombus_ sp., _Xylocopa_ s.str. _valga_ [PERSON], and _Apis cerana_[40]. Although the volatile compounds of many plants of the Nymphaea family have been studied, the information on the microstructure of the flowers has not been investigated before. Both the occurrence of the osmophilic matrix particles and the fragrance of the flowers of \(N\). _hybrid_ may have largely been overlooked until now. By detecting the aromas of the essential oils of red and violet \(N\). _hybrid_, [PERSON] et al. [33] found that its essential oil is relatively elegant and distinctive and suitable for use as a natural flavor additive in foods. In our research, it is worth noting that, compared with other strains of \(N\). _hybrid_, the yellow \(N\). _hybrid_ contains more esters and aldehydes, mainly benzyl acetate (12.18%) and benzaldehyde (6.62%). Benzyl acetate has a pleasant fruity flavor, and benzaldehyde has a fruity cherry aroma [59]. Due to the microstructures of the flower petals, total relative contents of volatile substances, and distributions of all classes of volatile substances, the yellow \(N\). _hybrid_ had particularly high concentrations of aromatic compounds, which can be distilled to obtain essential oils for applications such as aromotherapy, perfumes, flavorings, and food additives. Based on this study, alkenes, alcohols, and alkanes are the main volatile compounds responsible for the flower aroma of _N. hybrid_. The contributions of different volatile aroma compounds to flower aromas are affected by the odor activity values, flavor dilution factors, and aroma profiles.