Table 3.
Nitrate, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na) concentrations of lettuce grown hydroponically in a Fitotron open-gas-exchange growth chamber in relation to light conditions and cultivar.
| Source of variance | Nitrate (mg kg-1 fw) |
P (g kg-1 dw) |
K (g kg-1 dw) |
Ca (g kg-1 dw) |
Mg (g kg-1 dw) |
Na (g kg-1 dw) |
|---|---|---|---|---|---|---|
| Cultivar (C) | ||||||
| Baby Romaine | 2494 ± 54 b | 6.28 ± 0.62 a | 64.26 ± 1.30 | 6.73 ± 0.88 cd | 2.56 ± 0.09 bc | 0.33 ± 0.04 |
| Green Salanova | 2699 ± 136 ab | 5.86 ± 0.22 b | 68.00 ± 1.36 | 9.71 ± 0.77 b | 2.31 ± 0.19 d | 0.37 ± 0.03 |
| Lollo rossa | 2081 ± 160 c | 5.56 ± 0.26 bc | 65.03 ± 3.22 | 6.14 ± 0.49 d | 2.62 ± 0.09 bc | 0.36 ± 0.06 |
| Lollo verde | 2806 ± 177 a | 5.16 ± 0.19 cd | 62.04 ± 1.18 | 10.94 ± 1.16 a | 2.91 ± 0.08 a | 0.55 ± 0.14 |
| Red oak leaf | 2084 ± 34 c | 5.08 ± 0.17 d | 60.44 ± 1.10 | 7.44 ± 0.69 c | 2.70 ± 0.06 b | 0.31 ± 0.01 |
| Red Salanova | 2108 ± 114 c | 5.61 ± 0.17 bc | 66.43 ± 2.65 | 6.01 ± 0.43 d | 2.45 ± 0.11 cd | 0.30 ± 0.02 |
| Light intensity (μmol m−2 s−1) (L) | ||||||
| 420 (Optimal) | 2275 ± 56 b | 5.16 ± 0.10 b | 65.15 ± 1.08 | 6.27 ± 0.37 b | 2.66 ± 0.05 a | 0.41 ± 0.05 |
| 210 (Low) | 2482 ± 124 a | 6.02 ± 0.21 a | 63.58 ± 1.35 | 9.38 ± 0.58 a | 2.56 ± 0.08 b | 0.33 ± 0.01 |
| C × L | ||||||
| Baby Romaine × Optimal | 2419 ± 90 cde | 4.90 ± 0.03 de | 66.56 ± 1.76 | 4.78 ± 0.14 h | 2.38 ± 0.07 cd | 0.32 ± 0.08 |
| Green Salanova × Optimal | 2423 ± 38 cde | 5.42 ± 0.13 cd | 65.08 ± 0.60 | 8.05 ± 0.32 cd | 2.65 ± 0.08 abcd | 0.33 ± 0.02 |
| Lollo rossa × Optimal | 1974 ± 69 e | 5.68 ± 0.11 bc | 66.19 ± 1.65 | 5.14 ± 0.16 gh | 2.67 ± 0.04 abc | 0.42 ± 0.13 |
| Lollo verde × Optimal | 2461 ± 61 cd | 4.82 ± 0.16 de | 60.55 ± 2.05 | 8.42 ± 0.53 c | 2.96 ± 0.09 a | 0.76 ± 0.23 |
| Red oak leaf × Optimal | 2152 ± 4.0 cde | 4.71 ± 0.05 e | 62.71 ± 0.82 | 5.96 ± 0.40 fg | 2.70 ± 0.11 abc | 0.30 ± 0.02 |
| Red Salanova x Optimal | 2223 ± 221 cde | 5.42 ± 0.32 cd | 69.81 ± 4.77 | 5.30 ± 0.59 gh | 2.61 ± 0.11 abcd | 0.31 ± 0.03 |
| Baby Romaine × Low | 2570 ± 29 bc | 7.65 ± 0.18 a | 61.95 ± 0.17 | 8.68 ± 0.20 c | 2.74 ± 0.07 abc | 0.33 ± 0.06 |
| Green Salanova × Low | 2975 ± 121 ab | 6.31 ± 0.17 b | 70.92 ± 0.65 | 11.38 ± 0.34 b | 1.98 ± 0.02 e | 0.40 ± 0.04 |
| Lollo rossa × Low | 2189 ± 335 cde | 5.44 ± 0.55 cd | 63.87 ± 6.91 | 7.13 ± 0.42 de | 2.57 ± 0.20 bcd | 0.30 ± 0.02 |
| Lollo verde × Low | 3151 ± 185 a | 5.50 ± 0.20 cd | 63.52 ± 0.77 | 13.47 ± 0.17 a | 2.86 ± 0.13 ab | 0.35 ± 0.02 |
| Red oak leaf × Low | 2015 ± 31 de | 5.45 ± 0.08 cd | 58.18 ± 0.51 | 8.93 ± 0.11 c | 2.71 ± 0.05 abc | 0.32 ± 0.02 |
| Red Salanova × Low | 1993 ± 60 e | 5.80 ± 0.10 bc | 63.04 ± 0.90 | 6.72 ± 0.31 ef | 2.30 ± 0.15 de | 0.30 ± 0.01 |
| Significance | ||||||
| C | *** | *** | ns | *** | *** | ns |
| L | ** | *** | ns | *** | * | ns |
| C × L | ** | *** | ns | *** | ** | ns |
NS,*,**, *** Non-significant or significant at P ≤ 0.05, 0.01, and 0.001, respectively. Different letters within each column indicate significant differences at P ≤ 0.05. All data are expressed as mean ± SE, n = 3.