## 3 Results
### Temporal Variability
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Flowering Phase**} & \multicolumn{2}{c}{**Sample 1**} & **Sample 2** & **Sample 1** & **Sample 2** \\ \cline{2-5}  & \multicolumn{4}{c}{**Early**} & \multicolumn{2}{c}{**Late**} \\ \hline
**Compound** & **r.t. [min]** & \multicolumn{4}{c}{**Area \%**} \\ \hline \(\alpha\)-Pinene & 7.83 & & 0.24 & & 0.61 \\ \(\beta\)-Myrcene & 9.03 & & 0.29 & & 0.52 \\ D-Limonene & 9.84 & 0.54 & 1.00 & 0.66 & 2.01 \\ Sylvestrene & 11.25 & 0.54 & & & \\ Citronellal & 12.29 & & 1.50 & & 0.61 \\ \(\alpha\)-Terpineol & 13.17 & & 0.78 & & \\ Verbenone & 13.45 & 0.70 & 0.81 & 0.54 & 0.23 \\ Carvone & 14.07 & & 0.42 & & 0.35 \\ Citronellol & 14.14 & & 42.54 & & 15.66 \\ Methyl (S)-citronellate & 14.24 & 1.28 & 1.06 & 1.23 & \\ 4-Carene & 15.84 & & & & 2.63 \\ \(\alpha\)-Terpineol acetate & 15.85 & & & & 13.83 \\ (\(E\),\(Z\))-2,6-Dimethyl-2,6- & 15.87 & & 0.38 & & \\ Dihydro-b-ionone & 16.20 & 0.42 & & & \\
2-Methylene-4,8,8- & & & & & \\ trimethyl-4-vinylbicyclo & 16.70 & 2.52 & & & \\
[5.2.0]nonane & & & & & \\ Carvophyllene & 17.12 & 34.56 & 3.34 & 32.35 & \\ \(\alpha\)-Bergamotene & 17.29 & 1.10 & 0.50 & & 2.74 \\ (\(Z\))-\(\beta\)-Farrnesene & 17.47 & & 1.50 & 0.57 & 1.99 \\ trans-Geranylacetone & 17.50 & & & & 0.73 \\ (\(E\))-\(\beta\)-Farrnesene & 17.60 & & & 5.29 & & \\
4-Methylletradecane & 17.65 & & & 30.68 & \\ \(\alpha\)-longipinene & 17.97 & & & & 0.36 \\ Pentadecane & 18.17 & 4.27 & & 3.78 & \\ \(\delta\)-Selinence & 18.30 & & & & 0.32 \\ \(\beta\)-Bisabolene & 18.42 & 4.85 & 3.82 & 6.53 & 6.98 \\ \(\beta\)-Sesquiphellandrene & 19.35 & & 24.95 & & 44.13 \\ Elemene & 19.54 & 1.14 & & & \\ Hexadecane & 19.65 & 0.98 & & 0.37 & \\
8-Heptdecene & 20.80 & 1.47 & & 1.60 & \\
2,3-Dihydrofarnesol & 21.08 & 34.80 & 11.28 & 17.15 & 1.02 \\
2,6- & & & & & \\ Disopropylnaphthalene & 21.23 & 0.98 & & & \\ Octadecane & 22.41 & 0.98 & & 1.12 & \\ (E)-5-Octadecene & 22.55 & 1.47 & & & \\ Isopropyl miristate & 22.78 & 0.89 & 0.90 & 0.83 & 0.23 \\ Phytone & 22.90 & & & & 1.09 & \\
4-Octadecylmorfoline & 23.60 & 1.40 & & & 0.37 & \\ Nonadecane & 23.70 & & & & \\ Methyl hexadecanoate & 24.05 & 0.42 & & & \\ (\(E\),\(Z\))-5,9,13-Trimethyl- & & & & & \\
4,8,12-tetradecatrirenal & 24.32 & 1.61 & & & \\ trans-Geranylgeraniol & 26.50 & 1.61 & & & \\ \hline
**Number of compounds** & \multicolumn{2}{c}{**22**} & **18** & **15** & **18** \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of VOCs emitted by two plant samples of _Barlia robertiana_ from the S. Arcangelo site (Basilicata region, S-Italy) detected during the first part of the flowering phase with respect to the last part of the flowering. components; surprisingly, these two compounds were completely absent from the sample of the following year, substituted by \(\alpha\)-terpinolene and (_E_)-\(\beta\)-farnesene. Additionally, the other two individuals analyzed gave similar results for the main components: in the plant from Potenza, verbenone and D-carvone were not detected in the second year of sampling, which gave pristane and farnesol as the two dominant VOCs. Regarding the plant from S. Arcangelo, verbenone, the main component in 2018, was almost absent in 2019 (0.81%), whereas \(\delta\)-selinene, which was the second most abundant, was no more detected. Instead, the main component in 2019 resulted citronellol and \(\beta\)-sesquiphellandrene. Consequently, the inter-annual between-sample similarity, measured through the Bray-Curtis index, reached only very low values, lower than 9% (Calciano 4.6%, Arcangelo 5.1%, Potenza 8.9).