## 3 Results and Discussions
### Chlorophylll Determination
#### 3.4.1 Chlorophyll Rates on at LEAF Measurements  
The atLEAF chlorophyll measurements showed statistically significant differences between the two studied periods (t1 and t2), with the highest values reached in t2 (average index in t2 49.8 versus 48.4 in t1) (data not shown). The increase in the measured chlorophyll content in t2 is assumed to be caused by the rising requirements of photosynthesis products during flowering and strobiles formation. In the comparison of treatments, the lowest chlorophyll value was found in Treat 1 in t1 (45.05 atLeaf index) and Treat 1 and Treat 3 in t1 and t2 in t1 (47.78 and 47.06 atLeaf index in t2) (Figure 3A). The highest chlorophyll value was found, instead, in the two periods in Treat 2 (51.26 and 53.84 atLeaf index). Treat 2 was the treatment with the highest amount of nitrogen supplied, while Treat 1 was the treatment with the lowest (Table 1); an increase in chlorophyll content due to nitrogen fertilization was observed in different studies [44; 45], in particular, [PERSON] and collaborators [46] in a study on lettuce; the researchers also observed an important increase of chlorophyll content when plants were fertilized with a mix of elements used by plants in chlorophyll biosynthesis (Mn, Mg, Cu, Zn and Ca), and it is well known that Mn contributes to chloroplast structure.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Time** & **Untreat** & **Treat 1** & **Treat 2** & **Treat 3** & **Treat 4** \\ \hline \multirow{4}{*}{t1} & SD (number/mm\({}^{2}\)) & 671.64 \(\pm\) 40 b & 689.55 \(\pm\) 33 b & 776.12 \(\pm\) 35 ab & 794.03 \(\pm\) 35 a & 719.4 \(\pm\) 31 ab \\  & PD (\(\upmu\)m) & 19.4 \(\pm\) 1.6 a & 17.7 \(\pm\) 2.2 b & 18.4 \(\pm\) 1.7 ab & 19.7 \(\pm\) 2.1 a & 19.9 \(\pm\) 1.6 a \\  & ED (\(\upmu\)m) & 11.2 \(\pm\) 1.0 ab & 10.3 \(\pm\) 1.3 c & 10.6 \(\pm\) 1.2 bc & 10.0 \(\pm\) 0.8 c & 11.8 \(\pm\) 1 a \\  & Ratio PD/ED & 1.74 \(\pm\) 0.23 b & 1.75 \(\pm\) 0.31 b & 1.76 \(\pm\) 0.27 ab & 1.97 \(\pm\) 0.18 a & 1.69 \(\pm\) 0.18 b \\  & TD (number mm\({}^{2}\)) & 2.0 \(\pm\) 0.22 a & 2.27 \(\pm\) 0.20 a & 1.93 \(\pm\) 0.10 a & 2.06 \(\pm\) 0.17 a & 1.93 \(\pm\) 0.10 a \\  & NTD (number mm\({}^{2}\)) & 12.7 \(\pm\) 0.81 a & 10.04 \(\pm\) 0.63 b & 10.04 \(\pm\) 0.42 b & 12.85 \(\pm\) 0.51 a & 8.86 \(\pm\) 0.75 b \\ \hline \multirow{4}{*}{t2} & SD (number/mm\({}^{2}\)) & 674.63 \(\pm\) 32.5 ab & 710.45 \(\pm\) 29.7 ab & 728.36 \(\pm\) 27.5 a & 662.69 \(\pm\) 32.5 & 567.16 \(\pm\) 23 c \\  & PD (\(\upmu\)m) & 18.1 \(\pm\) 2.6 ab & 16.4 \(\pm\) 2.3 b & 18.5 \(\pm\) 2.6 a & 17.7 \(\pm\) 2.0 ab & 18.7 \(\pm\) 1.8 a \\  & ED (\(\upmu\)m) & 9.52 \(\pm\) 1.2 b & 9.32 \(\pm\) 1.3 b & 10.6 \(\pm\) 1.4 a & 10.9 \(\pm\) 1.2 a & 11.4 \(\pm\) 1.0 a \\  & Ratio PD/ED & 1.93 \(\pm\) 0.38 a & 1.78 \(\pm\) 0.32 ab & 1.77 \(\pm\) 0.35 ab & 1.66 \(\pm\) 0.30 b & 1.65 \(\pm\) 0.22 b \\  & TD (number mm\({}^{2}\)) & 1.98 \(\pm\) 0.15 a & 1.67 \(\pm\) 0.12 ab & 1.36 \(\pm\) 0.20 b & 1.64 \(\pm\) 0.16 b & 1.32 \(\pm\) 0.25 b \\  & NTD (number mm\({}^{2}\)) & 10.63 \(\pm\) 0.55 b & 16.84 \(\pm\) 0.69 a & 10.87 \(\pm\) 0.87 b & 10.93 \(\pm\) 0.71 b & 7.68 \(\pm\) 0.43 c \\ \hline \end{tabular} Abbreviations: SD: stomatal Density; PD: Stomatal Polar Diameter; ED: Stomatal Equatorial Diameter; TD Gandular Trichomes Density; NTD: Non-Glandular Trichomes density.  
\end{table}
Table 5: Characteristics of hop foliar features after each treatment at each time. In column and for each parameter, different letters indicate significant differences (\(p<0.05\)).