Table 1.
Physical and chemical parameters of substrates.
| Substrate | Bulk density | Total pore space | Air capacity | Total water-holding capacity | Chlorides in drain | EC | pH |
|---|---|---|---|---|---|---|---|
| Unit | kg · L–1 | % | % | L · m–3 | g · L–1 | mS · cm–1 | |
| Mineral wool | 0.064 | 97.13 | 15.6 | 815 | 0.006 | 0.247 | 6.6 |
| Perlite | 0.11 | 59.97 | 30 | 300 | 0.008 | 0.0828 | 7.99 |
| Coco peat | 0.081 | 77.48 | 4.4 | 730 | 0.029 | 0.528 | 4.85 |
| Wood fibre | 0.064 | 76 | 12.8 | 632 | 0.011 | 0.248 | 6.25 |
| Sheep wool | 0.048 | 96.77 | 77 | 198 | 0.094 | 6.24 | 7.97 |
Table 2.
Elements content in the drains from the substrates (mg · L–1).
| Element | Perlite | Mineral wool | Wood fibre | Sheep wool | Coco peat |
|---|---|---|---|---|---|
| P | 0.4 ± 0.0 a | 0.2 ± 0.0 a | 2.6 ± 0.0 b | 22.5 ± 0.5 d | 4.3 ± 0.1 c |
| K | 30.4 ± 1.1 c | 12.1 ± 0.2 a | 22.6 ± 0.7 b | 2,995.9 ± 1.5 e | 103.0 ± 3.0 d |
| S | 0.9 ± 0.1 a | 45.3 ± 1.8 c | 1.6 ± 0.0 a | 69.3 ± 1.4 d | 10.8 ± 0.4 b |
| Ca | 4.6 ± 0.5 a | 14.6 ± 0.5 b | 7.0 ± 0.5 a | 126.6 ± 1.2 d | 32.6 ± 1.4 c |
| Na | 4.8 ± 0.3 a | 43.9 ± 1.9 c | 6.1 ± 0.2 a | 57.5 ± 2.0 d | 33.7 ± 0.8 b |
| Fe | 1.7 ± 0.5 b | 0.3 ± 0.1 a | 0.2 ± 0.0 a | 10.9 ± 0.2 d | 4.2 ± 0.1 c |
| Mg | 1.1 ± 0.2 a | 4.8 ± 0.0 a | 2.5 ± 0.1 a | 30.1 ± 2.6 c | 12.5 ± 0.2 b |
| Zn | 0.0 ± 0.0 a | 0.0 ± 0.0 a | 0.1 ± 0.0 a | 1.2 ± 0.1 c | 0.2 ± 0.0 b |
| Sum | 44.0 ± 0.8 a | 121.2 ± 3.5 b | 42.8 ± 1.8 a | 3,314.0 ± 7.8 d | 201.4 ± 5.4 c |
Figure 1.
Leaf biomass (g). Different letters above the individual columns indicate significant differences at p ≤ 0.05. Error bars represent standard deviation.
Figure 2.
Number of leaves (pcs). Different letters above individual columns indicate significant differences at p ≤ 0.05. Error bars represent standard deviation.
Figure 3.
Stem diameter (mm). Different letters above individual columns indicate significant differences at p ≤ 0.05. Error bars represent standard deviation.
Figure 4.
Leaf area of the entire head of lettuce (cm2). Different letters above individual columns indicate significant differences at p ≤ 0.05. Error bars represent standard deviation.
Table 3.
Analytical parameters of lettuce. The table shows average values with standard deviation.
| Substrate Perlite | AA (% scavenging of DPPH) | GSH (mg · g–1 DM) | APX (AsA · g–1 FM · min–1) | TPC (mg GAE · g–1 FM) | Nitrates (mg · kg–1 FM) |
|---|---|---|---|---|---|
| Perlite | 21.6 ± 4.9 a | 44.0 ± 19.7 a | 108.8 ± 58.5 a | 43.3 ± 0.9 a | 604.2 ± 110.3 ab |
| Rockwool | 32.6 ± 3.0 ab | 22.5 ± 12.1 a | 129.6 ± 25.6 a | 40.6 ± 1.6 a | 555.1 ± 58.1 ab |
| Wood fibre | 46.1 ± 5.9 bc | 31.0 ± 4.9 a | 105.0 ± 32.2 a | 55.4 ± 7.9 b | 447.6 ± 38.2 a |
| Sheep wool | 54.9 ± 11.5 c | 23.1 ± 5.2 a | 135.9 ± 24.5 a | 74.0 ± 1.3 c | 686.2 ± 86.5 b |
| Coco peat | 40.3 ± 2.7 abc | 19.9 ± 2.5 a | 126.4 ± 25.5 a | 48.0 ± 1.6 ab | 552.6 ± 69.9 ab |
Figure 5.
Graph of multiple regression analysis between AA (% scavenging of DPPH) and content of TPC (p = 0.002449). AA, antioxidant activity; DPPH, 2,2-diphenyl-1-picrylhydrazyl; FM, fresh mass; TPC, total phenol content.