## 2 Results and Discussion
### Hop Cone Analysis  
#### 2.3.1 GC-MS Hop Oil Analysis  
In hops, the essential oil composition is influenced by several biotic and abiotic factors, plant nutrition being one of them. Fertilisation treatments could either be a useful tool to obtain optimum crop yields and quality results or, conversely, could be a source of stress for plants. From the GC-MS analysis of the cones coming from the 5 different fertilisation treatments (Figure S1), 16 terpen were identified (Table 3), corresponding to 89 \(\pm\) 1% of the total peak area. From these results, it was possible to observe differences in the aromatic profile: eight compounds showed statistical differences within the studied samples (Table 3), namely \(\beta\)-pinene, \(\beta\)-myrrene, \(\beta\)-careophyllne, \(\alpha\)-humulene, muurolene, \(\beta\)-selinene, \(\alpha\)-selinene and \(\tau\)-cadinene. The data in the table show a statistical difference in general between the treatments and the control, whereas there are slight significant differences between the treatments in essential oil composition (muurolene). The data demonstrate that the essential oils composition is less influenced by the different mixture of foliar fertilisation applied if compared to the resin composition (Table 2) [22]. The results demonstrate the complicated correlation between the nutrient input and plant response. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Treatment** & **\(\alpha\)-Acids \%** & **\(\beta\)-Acids \%** & **COH \%** & \multicolumn{3}{c}{**Ess. Oil Yield \%**} & **Moisture \%** \\ \hline C & 4.3 \(\pm\) 0.3 c & 5.3 \(\pm\) 0.2 b & 26.2 \(\pm\) 0.5 a & 1.1 \(\pm\) 0.1 c & 11.1 \(\pm\) 0.1 a \\ T1 & 5.8 \(\pm\) 0.4 b & 4.9 \(\pm\) 0.5 b & 26.7 \(\pm\) 0.5 a & 1.4 \(\pm\) 0.1 b & 10.0 \(\pm\) 0.1 a \\ T2 & 7.0 \(\pm\) 0.3 a & 6.4 \(\pm\) 0.1 a & 26.8 \(\pm\) 0.1 a & 1.8 \(\pm\) 0.1 a & 10.1 \(\pm\) 0.2 a \\ T3 & 5.8 \(\pm\) 0.6 b & 5.3 \(\pm\) 0.2 b & 26.1 \(\pm\) 0.4 a & 1.5 \(\pm\) 0.2 b & 10.5 \(\pm\) 0.2 a \\ T4 & 5.1 \(\pm\) 0.1 bc & 5.05 \(\pm\) 0.2 b & 26.2 \(\pm\) 0.4 a & 1.3 \(\pm\) 0.1 b & 10.1 \(\pm\) 0.1 a \\ \hline \hline \end{tabular}  
* C = control treatment; T1 = Treatment 1; T2 = Treatment 2; T3 = Treatment 3; T4 = Treatment 4.  
\end{table} 
Table 2: Bitter acid (\(\alpha\)- and \(\beta\)-acids) content (% \(w/w\) per dry weight), cohumulone (COH, % on the total of alpha acids) and essential oil yield (% \(v/w\)) of the studied hop samples [22] and moisture content (% \(w/w\)), means and standard deviation. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline
**Treatment** & **N Org.** & **P\({}_{2}\)O\({}_{5}\)** & **K\({}_{2}\)O** & **Mg** & **Zn** & **Zn** & **Mn** & **Mn** & **Fe** & **Cu** & **Cu** & **B** & **Mo** \\  & & & **Chel** & **Solub** & **Chel** & **Solub** & **Chel** & **Solub** & **Chel** & **Solub** & **Chel** & **Solub** & **Solub** \\ \hline T1 & 30 & 1125 & 2070 & 360 & 45 & 45 & 120 & 120 & 120 & 120 & 45 & 45 & 15 & 18 \\ T2 & 16,230 & - & 570 & 270 & 45 & 45 & 120 & 120 & 120 & 120 & 45 & 45 & 15 & 3 \\ T3 & 16,080 & 3600 & 19,170 & 180 & 21 & 21 & - & - & 1950 & 1950 & - & - & - & - \\ T4 & 16,080 & - & 16,770 & - & 66 & 66 & 120 & 120 & 2070 & 02700 & 45 & 45 & 345 & 3 \\ \hline \hline \end{tabular}  
* C = control treatment; T1 = Treatment 1; T2 = Treatment 2; T3 = Treatment 3; T4 = Treatment 4.  
\end{table} 
Table 1: Macro- and microelements (g ha\({}^{-1}\)) included in every nutrient mixture per treatment [22]. The compounds \(\beta\)-pinene and \(\beta\)-myrcene were less present in the C (control samples) condition, highlighting the impact of fertilisation treatments on aromatic compound biosynthesis. In contrast, the majority of the sesquiterpenes were found in higher amounts in the C (Table 3). These results are to some extent in line with those reported in a study on _Achyrocline satureioides_ (Lam.)