## 3 Results and Discussion
### Effect of Growing Medium on the Growth and Yield  
Cultivar and growing medium did not influence seed germination, as was expected for the latter based on the absence of phytotoxicity of the three composts, and the pH and EC values measured in all compost-containing substrates, which, compared to those of the control, could be presumed not to inhibit germination. Statistical analysis performed by two-way ANOVA on the growth components i.e., number of true leaves, plant height, and dry weight of organs (root, stem, and leaves), at 33 days after sowing, showed that the parameters considered were affected by the cultivar and growing medium and their interaction, except for the root dry weight. Imperiale (IMP) lettuce showed significantly higher leaf number than Verde d'Inverno (VDI) (3.0 vs. 1.9), while lower height (6.9 vs. 8.7 cm). The dry weight of stem and leaves was significantly higher for VDI compared to IMP (10.60 vs. 5.27, 19.14 vs. 15.98, respectively). In Table 5, the effect of the cultivar (C) and growing medium (GM) interaction on leaf number; plant height; and root, stem, and leaves dry weight 33 days after sowing is \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Growing** & **C** & **N** & **EC** & **Ash** \\
**Medium** & **\% d.m** & **\% d.m.** & **pH** & **dS/m** & **\% d.m.** \\ \hline TC & 51.0 \(\pm\) 0.2 & 1.4 \(\pm\) 0.02 & 6.0 \(\pm\) 0.1 & 0.35 \(\pm\) 0.0 & 9.6 \(\pm\) 0.8 \\ C1-60 & 42.2 \(\pm\) 0.1 & 2.3 \(\pm\) 0.09 & 7.2 \(\pm\) 0.2 & 0.68 \(\pm\) 0.2 & 18.2 \(\pm\) 1.6 \\ C1-30 & 46.9 \(\pm\) 0.9 & 1.8 \(\pm\) 0.10 & 6.4 \(\pm\) 0.2 & 0.52 \(\pm\) 0.1 & 10.7 \(\pm\) 1.3 \\ C2-60 & 36.0 \(\pm\) 0.8 & 2.7 \(\pm\) 0.10 & 7.3 \(\pm\) 0.3 & 0.60 \(\pm\) 0.2 & 26.6 \(\pm\) 0.9 \\ C2-30 & 45.7 \(\pm\) 0.2 & 1.6 \(\pm\) 0.01 & 6.4 \(\pm\) 0.1 & 0.47 \(\pm\) 0.1 & 15.5 \(\pm\) 1.8 \\ C3-60 & 41.8 \(\pm\) 0.6 & 2.7 \(\pm\) 0.11 & 7.1 \(\pm\) 0.3 & 0.50 \(\pm\) 0.1 & 17.8 \(\pm\) 1.0 \\ C3-30 & 47.3 \(\pm\) 0.3 & 1.9 \(\pm\) 0.01 & 6.4 \(\pm\) 0.2 & 0.63 \(\pm\) 0.2 & 13.3 \(\pm\) 1.1 \\ \hline \hline \end{tabular} The values are means \(\pm\) standard deviation: TC: Peat-based substrate; C1-60: 60% Compos1 + 40% Peat; C1-30: 30% Compos1 + 70% Peat; C2-60: 60% Compos2 + 40% Peat; C2-30: 30% Compos2 + 70% Peat; C3-30: 30% Compos3 + 70% Peat, and C3-60: 60% Compos3 + 40% Peat.  
\end{table} 
Table 4: Main chemical characteristics of the growing media utilized. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Compost** & **C** & **N** & **HA + HF** & **EC** & **Ash** & **GI** \\  & **\% d.m.** & **\% d.m.** & **\% d.m.** & **pH** & **dS/m** & **\% d.m.** & **\%** \\ \hline C1 & 37.9 \(\pm\) 0.5 & 3.4 \(\pm\) 0.1 & 11.0 \(\pm\) 0.3 & 18.4 \(\pm\) 5.1 & 7.9 \(\pm\) 0.2 & 0.90 \(\pm\) 0.1 & 21.5 \(\pm\) 2.1 & 124.1 \\ C2 & 35.2 \(\pm\) 0.6 & 2.2 \(\pm\) 0.1 & 16.3 \(\pm\) 0.7 & 11.8 \(\pm\) 0.0 & 8.0 \(\pm\) 0.4 & 0.77 \(\pm\) 0.2 & 32.3 \(\pm\) 1.9 & 132.8 \\ C3 & 41.1 \(\pm\) 0.1 & 2.6 \(\pm\) 0.1 & 15.8 \(\pm\) 0.2 & 21.8 \(\pm\) 0.1 & 7.9 \(\pm\) 0.3 & 0.82 \(\pm\) 0.3 & 22.1 \(\pm\) 2.2 & 118.8 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main chemical characteristics of the composts used. reported. The plant height of IMP lettuce was not affected by the growing medium, while VDI plants grown in C1-60 (VDI \(\times\) C1-60) showed a lower height compared with those grown in control (VDI \(\times\) TC). Similar values of dry weight (root, stem, leaf) of IMP plants grown with the different substrates were found; instead, VDI \(\times\) C1-30, VDI \(\times\) C2-60, and VDI \(\times\) C3-60 showed higher mean values of stem dry weight, compared with VDI \(\times\) TC. VDI \(\times\) C1-30 also positively influenced leaf dry weight. At 43 days after sowing, at 33 DAS, _VDI_ showed higher mean values than _IMP_ for all the parameters considered, except for leaf number.