## 3 Results and Discussion
### Effect of Growing Medium on the Growth and Yield
Figure 2: Effect of the cultivar (C) and growing medium (GM) interaction (significant at \(p<0.01\)) on yield (kg m\({}^{-2}\)) 54 days after sowing. Vertical bars represent the standard deviation of the mean values. Different letters indicate significant differences according to [PERSON]’s test at \(p\leq 0.05\). IMP: _Imperiale_ lettuce cv; VDI: _Verde d’Inverno_ lettuce cv; TC: Peat-based substrate; C1-60: 60% Compost 1 + 40% Peat; C1-30: 30% Compost 1 + 70% Peat; C2-60: 60% Compost 2 + 40% Peat; C2-30: 30% Compost 2 + 70% Peat; C3-30: 30% Compost 3 + 70% Peat; C3-60: 60% Compost 3 + 40% Peat. The average yield found in our experiment was comparable to that measured by [PERSON] et al. [72] who reported a yield of about 2.2 and 2.4 kg m\({}^{-2}\) of baby leaf lettuce (_Lactuca sativa_ L. cv Antoria (red lettuce) grown, respectively, in peat and compost (from fruit and vegetable wastes) in a floating system. Our results agree with [PERSON] et al. [73] who found no negative influence on plant development by compostos (from agricultural wastes) utilized as growing media for the production of baby leaf lettuce (_Lactuca sativa_ L., red lettuce) in a floating system. Moreover, as for our results, some compost-based substrates of cultivation improved plant growth more than the peat-based ones, achieving higher yields [73]. It has been shown that suitable characteristics of water-holding capacity, EC, aeration, and bulk density allow satisfactory conditions for healthy plant growth, which guarantees an increase in the photosynthetic potential of the leaves [11; 67; 69]. These characteristics are affected by the porosity in the media, which promotes plant growth [69]. Our results indicated that the cartoon-based compostos were suitable to meet this condition up to the highest peat replacement volume tested (60%). This is noteworthy since it has been reported that both plant growth and yields were higher when the volume of compost was in a relatively low quantity (25-50%) in the growing medium [15; 67]. [PERSON] and [PERSON] [74] indicated that the optimal amount of compost may depend on its type and reported that a 25% mixture of non-food waste compost and peat resulted in the best growth for lettuce. In addition, in work conducted to evaluate green compost and palm fiber trunk waste as peat replacement for seedling production, [PERSON] et al. [71] reported that optimal performance was reached with 20% and 35% peat for tomato and melon seedlings, respectively, while up to 60% peat was required for lettuce. In a study on the application of compost derived from fresh vegetable residues for the production of lettuce, [PERSON] et al. [75], evaluated different mixtures with the commercial substrate using four different cultivars and reported that the best results were obtained using compost amounts between 20.1 and 26.7% of the growing medium. Moreover, [PERSON] et al. [75] observed a significant interaction between cultivar and growing medium on plant fresh mass. Also, [PERSON] and [PERSON] [76] highlighted the interaction effects of lettuce cultivar type and compost (food waste-based) growing medium on the fresh weight of the shoots, as occurred in our findings. These findings point out the importance of a genotype-production system for this crop and show that some cultivars respond better to the use of compost [75].