## 4 Results  
The graphical visualization of NMD (stress value = 0.06) displayed a good separation of treatments (Figure 1) and this was statistically supported by PERMANOVA, which revealed a high significance of treatments (\(p\) < 0.001). The further analysis performed with ANOVA, followed by a Tukey test on the single or grouped compounds, revealed a significant effect of the NaCl concentration on most of the components (Tables 1 and 2). \begin{table}
\begin{tabular}{c l c c c c c} \hline \hline  & & & & & & \\ \hline
**No** & **Compounds** & **Kavats Index** & **0** & **50** & **100** & **150** \\ \hline
4 & Sabinene & 979 & 0.85 \(\pm\) 0.3 \({}^{\rm c}\) & 0.90 \(\pm\) 0.07 \({}^{\rm b}\) & 0.93 \(\pm\) 0.36 \({}^{\rm b}\) & 1.20 \(\pm\) 0.5 \({}^{\rm a}\) \\
5 & \(\alpha\)-Terpenyl acetate & 1357 & 5.70 \(\pm\) 0.13 \({}^{\rm b}\) & 6.74 \(\pm\) 0.63 \({}^{\rm ab}\) & 7.63 \(\pm\) 0.7 \({}^{\rm a}\) & 7.98 \(\pm\) 0.55 \({}^{\rm a}\) \\  
ricyclene & 934 & 0.93 \(\pm\) 0.07 \({}^{\rm b}\) & 1.06 \(\pm\) 0.28 \({}^{\rm aThe component percentages of the leaf VCs changed with the change of the salinity concentration, as reported in the Table 1. In fact, although the instrumentation detected and identified 181 compounds, many of with at very low level, we did not include in the table compounds present at a relative ratio lower than 0.1% (as an average of all treatments and replication), whose analysis did not reveal statistical significance of treatments; thus, only 53 of the 181 compounds are listed. The unidentified compounds ranged between 24.05 and 29.19% (Table 1). Results show that among the many compounds detected in the VCs occurred of laurel the most represented was 1,8-cineole (ranging from 12.6 to 18.4%), followed by \(\alpha\)-terpenyl acetate (from 5.7 to 7.9%) and methyl eugenol (from 5.1 to 6.5%). These and other compounds were commonly found with plants treated with salt stress but their relative amount increased, decreased or did not change under salt stress as compared with untreated plants. In fact, sabinene, \(\alpha\)-terpenyl acetate, eugenol, zingiberene and \(\alpha\)-copaene increased considerably with an increasing NaCl level. In contrast, \(\alpha\)- and \(\beta\)-pinene, 1,8-cineole, camphene, linalool, \(p\)-cymene, borneol, terpinen-4-ol and 3-ethyl-2,5-dimethylhexane were reduced with increasing NaCl concentration. It is worthy to note, in particular, that the relative amounts of 1,8-cineole (the major compound of laurel EO), was significantly affected by salinity, it decreased gradually with increasing NaCl level and achieved the lowest percentage at 100 NaCl, then at 150 mM NaCl it slightly but significantly increased again. Furthermore, as presented in the Table 1, the relative amount of \(\alpha\)-thujene, \(m\)-cymene, _trans_-pinocarveol, _cis-\(p\)-_mentha-1,3,8-triene, \(E\)-linalool oxide and 2,5-dimethoxy-\(p\)-cymene increased gradually with increasing salt stress and reached the highest values at 100 mM and then decreased at the highest level of NaCl (150 mM NaCl). Additionally, myrcene, bornyl acetate and methyl eugenol have, in absolute terms, the highest values with 100 mM NaCl. Finally, the relative amount of many other compounds, e.g., \(\alpha\)-terpinolene, limonene, \(\alpha\)-terpinene, _trans_-caryophyllene and \(\delta\)-terpinyl acetate, did not change. Grouped compounds of laurel VC are summarized in Table 2. The composition of laurel VC is primarily made up of oxygenated monoterenes. This group was the main group at different salt levels (about 40%) and with increasing NaCl concentration, the values for this group decreased. Monoterpene hydrocarbons were the second group for importance, producing the 13.71% of the total EO in the control plants and, also for this group, the relative EO amounts decreased with increasing NaCl levels. Differently, along with the increase of NaCl level, the relative amount of sesquiterpene hydrocarbons group increased reaching the highest values at 100 mM NaCl (7.17%).