## 2 Results
### Volatile Compounds of the Flower Petals of N. hybrid
#### 2.2.4 Relationships among Different Classes of Volatile Compounds  
Correlation analysis was used to explore the relationships among different classes of volatile compounds (Table 3). Ketones and alkanes were strongly negatively correlated with total alcohol content. Aldehydes were highly correlated with ester content (r = 0.945, \(p<\) 0.01) but negatively correlated with the contents of ketones and alkenes. Ketones were  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Categories**} & \multirow{2}{*}{**Volatile Compounds**} & \multicolumn{4}{c}{**Relative Content (\%) 1**} \\ \cline{3-6}  & & **Nh-1** & **Nh-2** & **Nh-3** & **Nh-4** \\ \hline Alcohols & Benzyl alcohol & 32.57 b  & 20.25 d  & 25.27 c  & 44.55 a  \\ \hline Esters & Benzyl acetate & 0.61 b  & 0.29 b  & 12.18 a  & nd \\ \hline Aldehydes & Benzaldehyde & 0.98 b  & 0.56 c  & 6.62 a  & 1.94 b  \\ \hline Ketones & 2-Heptadecanone & 0.71 b  & 3.00 a  & 0.44 b  & 0.22 b  \\ \hline Alkanes & Pentadecane & 22.43 a  & 23.09 a  & 20.49 a  & 11.15 b  \\ \hline Alkanes & Heptadecane & 2.64 a  & 2.85 a  & 1.41 b  & 0.39 c  \\ \hline  & trans-\(\alpha\)-Bergamotene & 4.49 b  & 5.40 b  & 5.34 b  & 10.68 a  \\  & \(\alpha\)-Sesquiphellandrene & 1.18 c  & 3.77 a  & 0.80 d  & 2.62 b  \\  & (E)-\(\beta\)-Farresene & 5.51 b  & 4.59 b  & 5.13 b  & 7.26 a  \\  & \(\alpha\)-Curcumene & 2.96 a  & 2.26 a  & 1.82 b  & 0.32 c  \\ \cline{2-5}  & \(\alpha\)-Bisabolene & 2.69 a  & 0.13 c  & 1.73 b  & 1.39 b  \\  & (6E,9E)-6,9-Heptadecadiene & 9.96 b  & 15.76 a  & 6.88 c  & 3.67 d  \\  & 8-Heptadecene & 3.87 b  & 5.66 a [FONOTE:a]Footnote a: footnotemark: [ENDFOOTNOTE] & 3.60 b  & 1.28 c  \\ \hline  & Total & 90.61 a  & 87.62 b  & 91.70 a  & 85.48 b  \\ \hline \hline \end{tabular}  
* Statistical analyses were performed with [PERSON]’s multiple range test. Means with different letters (a, b, c, d) within a row are significantly different at \(p<\) 0.05.  
\end{table}
Table 2: Comparison of the main volatile compounds in _N. hybrid_.  
significantly correlated with alkanes and alkenes. However, no significant relationships were found among alcohols, esters, and aldehydes.  
These correlations can aid the selection of varieties with improved aroma qualities, since selection for one trait may lead to selection for genetically improved traits. The relationships among different volatile compounds indicate the complexity of flower aroma metabolites.  
Figure 5: Percentages of alcohols, esters, aldehydes, ketones, alkanes, alkenes, and other volatile compounds released from fully open flower petals of _N. hybrid_.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Alcohols** & **Esters** & **Aldehydes** & **Ketones** & **Alkanes** & **Alkenes** & **Others** \\ \hline Alcohols & \(1\) & & & & & & \\ Esters & \(-0.272\) & & & & & & \\ Aldehydes & \(-0.131\) & \(0.945\)** & \(1\) & & & & \\ Ketones & \(-0.579\)* & \(-0.545\) & \(-0.629\)* & \(1\) & & & \\ Alkanes & \(-0.835\)** & \(-0.056\) & \(-0.199\) & \(0.618\)* & \(1\) & & \\ Alkenes & \(-0.461\) & \(-0.660\)* & \(-0.699\)* & \(0.934\)** & \(0.465\) & \(1\) & \\ Others & \(-0.927\)** & \(-0.043\) & \(-0.168\) & \(0.005\) & \(0.823\)** & \(0.705\)** & \(1\) \\ \hline \hline \end{tabular}  
* Significant correlation at \(p<0.05\). ** Significant correlation at \(p<0.01\).  
\end{table}
Table 3: Linear correlation coefficients among different classes of volatile compounds.