## 3 Results  
### VOC Identification  
The empirical distribution of observations of all VOCs was normal. In total nine volatiles were identified, namely (Z)-3-hexenal (retention time: 5.59 min), (E)-2-hexenal (8.32 min), (Z)-3-hexen-1-ol (9.02 min), (E)-2-hexen-1-ol (9.16 min), (Z)-3-hexen-1-yl acetate (13.45 min), (E)-\(\beta\)-ocimene (15.36 min), linalool (17.35 min), \(\beta\)-caryophyllene (26.02 min) and (E)-\(\beta\)-farnesene (26.25 min). However, not all were necessarily detectable at the same time depending on the type of artificial stress. For example, \(\beta\)-caryophyllene, and \(\beta\)-farnesene were not observed (i.e., either no emissions or below the limits of detection) at any of the sampling time points following mechanical leaf damage to the \"Kandela\" variety. In addition, for the \"Kandela\" variety, no (E)-2-hexenal and (Z)-3-hexen-1-ol were detected at any collection time points from plants that were sprayed with MeJA. Similarly, both varieties of wheat sprayed with MeJA showed no detectable emissions of (E)-2-hexen-1-ol. Mean values for the volatile emission rates and combinations of cultivars and times for the observed VOCs are presented in Table 2. The first and the most important observation is that the level of VOC emissions from controls is significantly lower than those coming from the plants that are exposed to artificial stress. Results of ANOVA indicate that all factors (i.e., cultivars, time, and cultivar \(\times\) time interaction) were significant for all VOCs in all four treatments: 1 SL, 3 SL, MJ-V, and MJ-S (see Table 3). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Cultivar**} & \multirow{2}{*}{**Time**} & \multirow{2}{*}{**Cultivar**} & \multirow{2}{*}{**Time**} & \multirow{2}{*}{**Cultivar**} & \multirow{2}{*}{**Cultivar**} & \multirow{2}{*}{**Cultivar**} & \multirow{2}{*}{**Cultivar**} & \multirow{2}{*}{**Cultivar**} & \multirow{2}{*}{**Cultivar**} & \multirow{2}{*}{**Cultivar**} \\ \cline{3-3} \cline{6-11}  & & & & & & & & & & \\ \hline \hline \multirow{4}{*}{Kandela} & Control & 1.53 & 1.92 & 1.05 & 0.53 & 1.6 & 1.13 & 1.82 & -2 & - \\ \cline{2-11}  & 24 h & 80.52 & 28.98 & 61.55 & 7.77 & 136.58 & 10.95 & 14.52 & - & - \\ \cline{2-11}  & 48 h & 82.12 & 27.4 & 50.63 & 8.127 & 117.6 & 93.33 & 102.27 & - & - \\ \cline{2-11}  & 72 h & 37.88 & 3.55 & 32.45 & 3.62 & 28.53 & 86.28 & 79.63 & - & - \\ \hline \multirow{4}{*}{Serenada} & Control & 4.45 & 1.38 & 0.78 & 0.98 & 1.8 & 1.53 & 1.72 & 1.18 & 1.33 \\  & 24 h & 108.27 & 47.93 & 84.62 & 13.47 & 215.53 & 17.15 & 19.43 & 14.82 & 16.12 \\  & 48 h & 175.35 & 47.2 & 77.22 & 13.92 & 198.6 & 223.42 & 171.57 & 134.88 & 106.72 \\  & 72 h & 64.92 & 9.53 & 60.5 & 9.17 & 29.2 & 117.65 & 120.03 & 83.08 & 98.98 \\ \hline \multirow{4}{*}{\(\mathrm{LSD}_{0,001}\)\({}^{1}\)} & Culivar & 22.86 & 6.742 & 4.807 & 1.78 & 17.37 & 28.62 & 24.5 & 12.2 & 15.18 \\  & Time & 32.32 & 9.535 & 6.798 & 2.52 & 24.57 & 40.48 & 34.64 & 17.26 & 21.47 \\ \cline{1-1}  & C \(\times\) T & 45.71 & 13.485 & 9.614 & 3.56 & 34.75 & 57.25 & 48.99 & 24.4 & 30.37 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mean values for two wheat cultivars corresponding to the fixed three volatile sample collection times following a given artificial stress (n = 6).