## 3 Results and Discussion
### Profile in VOCs
#### 3.1.1 Chemical Groups of Volatiles
\begin{table}
\begin{tabular}{l c c c c} \hline \hline  & **Isothiocyanates** & **Esters** & **Others** & **Total** \\ \hline DER006 & \(819.^{\circ}\)(81.1) & \(87.5^{\circ}\)(8.6) & \(103.6^{\circ}\)(10.3) & \(1011.0^{\rm bc}\) \\ DER008 & \(741.2^{\circ}\)(79.1) & \(112.4^{\rm a}\)(12.0) & \(83.1^{\rm a}\)(8.9) & \(936.7^{\rm bc}\) \\ DER014 & \(340.7^{\rm bc}\)(64.4) & \(148.9^{\rm a}\)(28.2) & \(39.2^{\rm a}\)(7.4) & \(528.8^{\rm ab}\) \\ DER021 & \(456.9^{\rm bc}\)(71.3) & \(96.0^{\rm a}\)(15.0) & \(87.9^{\rm bcd}\)(13.7) & \(640.7^{\rm abc}\) \\ DER039 & \(1041.2^{\rm c}\)(86.8) & \(88.8^{\circ}\)(7.4) & \(68.9^{\rm a}\)(5.8) & \(1198.9^{\rm c}\) \\ DER040 & \(413.0^{\rm c}\)(59.7) & \(206.5^{\rm a}\)(29.9) & \(72.1^{\rm a}\)(10.4) & \(691.5^{\rm bc}\) \\ DER045 & \(186.2^{\rm a}\)(45.9) & \(182.2^{\rm a}\)(44.9) & \(37.1^{\rm a}\)(9.2) & \(405.6^{\rm a}\) \\ DER052 & \(715.4^{\circ}\)(79.7) & \(145.2^{\rm a}\)(16.2) & \(37.0^{\rm a}\)(4.1) & \(897.7^{\rm bc}\) \\ DER056 & \(1102.5^{\rm c}\)(88.9) & \(75.7^{\rm a}\)(6.1) & \(62.2^{\rm a}\)(5.0) & \(1240.4^{\rm c}\) \\ DER057 & \(1006.0^{\rm c}\)(87.8) & \(74.9^{\rm a}\)(6.5) & \(65.6^{\rm a}\)(5.7) & \(1146.5^{\rm c}\) \\ DER060 & \(882.9^{\rm c}\)(85.5) & \(81.5^{\rm a}\)(7.9) & \(68.6^{\rm a}\)(6.6) & \(1033.0^{\rm bc}\) \\ DER061 & \(906.2^{\rm c}\)(87.4) & \(88.9^{\rm a}\)(8.6) & \(41.4^{\rm a}\)(4.0) & \(1036.6^{\rm bc}\) \\ DER062 & \(630.1^{\rm bc}\)(74.6) & \(166.6^{\rm a}\)(19.7) & \(48.4^{\rm a}\)(5.7) & \(545.0^{\rm bc}\) \\ DER064 & \(729.9^{\rm c}\)(75.1) & \(143.3^{\rm a}\)(14.8) & \(98.7^{\rm c}\)(10.1) & \(972.3^{\rm bc}\) \\ DER067 & \(722.5^{\rm c}\)(83.5) & \(112.4^{\rm a}\)(13.0) & \(30.3^{\rm a}\)(3.5) & \(865.2^{\rm bc}\) \\ DER068 & \(230.8^{\rm b}\)(45.3) & \(248.2^{\rm a}\)(48.7) & \(30.7^{\rm a}\)(6.0) & \(509.7^{\rm ab}\) \\ DER069 & \(500.8^{\rm bc}\)(75.3) & \(139.4^{\rm a}\)(20.9) & \(25.3^{\rm abc}\)(3.8) & \(665.5^{\rm bc}\) \\ DER071 & \(498.5^{\rm bc}\)(82.3) & \(60.3^{\rm a}\)(9.9) & \(47.0^{\rm a}\)(7.8) & \(605.8^{\rm abc}\) \\ DER082 & \(647.4^{\rm c}\)(81.7) & \(122.1^{\rm a}\)(15.4) & \(23.0^{\rm abc}\)(2.9) & \(792.5^{\rm bc}\) \\ DER087 & \(909.1^{\rm c}\)(85.2) & \(62.2^{\rm a}\)(5.8) & \(96.1^{\rm bcd}\)(9.0) & \(1067.4^{\rm bc}\) \\ DER089 & \(1097.6^{\rm c}\)(91.1) & \(58.8^{\rm a}\)(4.9) & \(48.6^{\rm a}\)(4.0) & \(1205.1^{\rm c}\) \\ DER096 & \(696.8^{\rm c}\)(81.5) & \(84.5^{\rm a}\)(9.9) & \(74.0^{\rm a}\)(8.6) & \(855.4^{\rm bc}\) \\ DER102 & \(674.4^{\rm c}\)(72.5) & \(138.1^{\rm a}\)(14.9) & \(117.3^{\rm a}\)(12.6) & \(929.8^{\rm bc}\) \\ DER103 & \(938.0^{\rm c}\)(91.4) & \(66.4^{\rm a}\)(6.5) & \(21.6^{\rm ab}\)(2.1) & \(1026.0^{\rm bc}\) \\ _Mean_ & _703.7 (80.0)_ & _116.3 (13.2)_ & _59.5 (6.8)_ & _879.5_ \\ \hline \hline \end{tabular} Different letters within columns indicate significant differences between means according to the Student-Newman-Keuls test (\(p=0.05\)).  
\end{table} 
Table 2: Absolute levels (GC-peak area units, \(\times 10^{6}\)) for the groups of volatile organic compounds identified in the wall rocket materials (\(n=3\)). The relative abundances (%, in parentheses) are also included. but not for the esters fraction. Indeed, the group of esters added between \(66.4\times 10^{6}\) (DER103) and \(248.2\times 10^{6}\) (DER068) GC-peak area units, with no significant differences among accessions due to the high intra-population variability. By contrast, there were significant differences between populations for the levels of ITCs, with DER045 showing the lowest level and DER056 the highest level, with an almost 6-fold increase. Sulfur compounds are commonly reported within the Brassicaceae [22; 29; 30; 31; 32]. In particular, they have been identified as the main fraction in the volatile profile of wall rocket microgreens and seedlings [4] and in stems, leaves and pods of wild, mature plants [33]. By contrast, the families of aldehydes and alcohols were not greatly represented in the current study, while they have been reported in other species like the related rocket crops [22; 33].