# Smart Hydroponic Cultivation System for Lettuce
## 2 Materials and Methods
### Monitoring and Control System
It can be observed that all growth variables, such as plant height, root length, stem diameter and number of leaves, showed no statistically significant differences among treatments, according to the ANOVA test with a 5% significance level. The results are presented as mean \(\pm\) standard deviation (SD). Figure 5:4 Daily behavior of the physicochemical variables of the nutrient solution during the cultivation experiment for the three treatments: T100 (100%), T75 (75%) and T50 (50%) nutrient concentration. The following values are shown: pH (**top left**), EC (**top right**), TDS (**bottom left**) and nutrient solution temperature (**bottom right**). Regarding fresh matter, a significant difference of 8.17 g was observed between T75 and T100 for root fresh mass. For leaf fresh mass, no significant difference was found, with the largest difference being 25.84 g between T75 and T100. In terms of dry mass, a statistically significant difference was found between T100 and the other treatments. This may be explained by a lower moisture concentration and a higher nutrient concentration in the T100 treatment. The observed difference in dry mass was 6.59 g between T100 and T75. During the cultivation period, chlorophyll content in the leaves was measured using SPAD index values, shown in Figure 5:5 There were no significant differences in chlorophyll content among treatments, suggesting that the consistent PPF values contributed to the homogeneity of chlorophyll levels, as illustrated in Figure 5:6 Leaf water mass was calculated by subtracting the dry leaf mass from the fresh leaf mass. To evaluate crop efficiency, dry leaf mass was measured for each treatment, revealing that the T100 treatment showed significantly higher values of leaf dry mass compared to T75 and T50, suggesting that greater nutrient availability promotes biomass accumulation. Figure 17 shows the arithmetic means of chlorophyll and dry leaf mass in the different treatments. Figure 5:7 Photograph of the cultivation experiment conducted in the plant growth chamber using the NFT hydroponic system (taken three days before harvest). The three applied treatments are shown: T100 (100%), T75 (75%) and T50 (50%) nutrient concentration. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & **Leaf** & **Root** & **Stem** & **N. of** & **Fresh** & **Fresh** & **Dry Leaf** & **Dry Root** & **Chlorophyll** & **Leaf** \\  & **Height** & **(cm)** & **Length** & **Width** & **Leaves** & **Leaf** & **Root** & **Mass (g)** & **Mass (g)** & **Mass (g)** & **(SPAD)** & **Water** \\  & **(cm)** & **(cm)** & **(cm)** & **(cm)** & **Mass (g)** & **Mass (g)** & **Mass (g)** & **Mass (g)** & **Mass (g)** & **Mass (g)** \\ \hline T50 & 21.33 \(\pm\) & 39.08 \(\pm\) & 17.43 \(\pm\) & 19.83 \(\pm\) & 167.83 \(\pm\) & 13.33 \(\pm\) & 9.89 \(\pm\) & 0.98 \(\pm\) & 157.94 \(\pm\) \\  & 1.47 a & 12.51 a & 3.88 a & 3.54 a & 56.54 a & 3.44 ab & 3.05 a & 0.40 a & & 54.47 a \\ \hline T75 & 21.08 \(\pm\) & 42.50 \(\pm\) & 16.46 \(\pm\) & 20.66 \(\pm\) & 154.66 \(\pm\) & 25.00 \(\pm\) & 8.11 \(\pm\) & 1.11 \(\pm\) & 38.93 \(\pm\) 4.83 a & 146.55 \(\pm\) \\  & 0.66 a & 12.18 a & 2.84 a & 1.97 a & 44.76 a & 10.58 a & 1.30 a & 0.38 a & & 44.72 a \\ \hline T100 & 23.50 \(\pm\) & 41.16 \(\pm\) & 18.10 \(\pm\) & 22.50 \(\pm\) & 180.50 \(\pm\) & 16.83 \(\pm\) & 14.70 \(\pm\) & 1.06 \(\pm\) & 165.8 \(\pm\) \\  & 2.97 a & 13.89 a & 5.14 a & 2.35 a & 40.85 a & 4.54 b & 1.73 b & 0.29 a & & 37.72 \(\pm\) 5.59 a & 39.18 a \\ \hline \hline \end{tabular} Different letters indicate significant differences between treatments (\(p<0.05\)).

\end{table} 
Table 3: Means and standard deviations (\(\pm\)SD) of the evaluated growth variables, including height, number of leaves, fresh and dry leaf mass, fresh and dry root mass, root length, stem width, leaf water mass and leaf chlorophyll content, according to the treatments applied during the cultivation experiment.