Table 3.
Effects of N condition and genotype on variation in the dry-matter-based N Use Efficiency (NUE_DM) and its components during the crop cycle in the three experiments.
| Sampling stage | GR18 (Grignon 2017–2018) | GR15 (Grignon 2014–2015) | LR15 (Le Rheu 2014–2015) | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low-N | %var | Low-N | High-N | %var | Low-N | High-N | Variance decomposition | ||||||||||||
| Trait | Unit | genotype mean | AVISO | G | AVISO | AVISO | N | genotype mean | AVISO | genotype mean | AVISO | G | N | GxN | |||||
| BBCH 16–18 | |||||||||||||||||||
| NUE_DM | g gN−1 | 1.39 | 1.28 | 57% | *** | – | – | – | 2.08 | 3.06 | 1.18 | 1.36 | 23% | *** | 31% | *** | 14% | ** | |
| NUpE | gN gN−1 | 0.07 | 0.07 | 53% | *** | – | – | – | 0.08 | 0.12 | 0.05 | 0.06 | 23% | *** | 30% | *** | 13% | ** | |
| NUtE | g gN−1 | 19.99 | 19.80 | 6% | ns | – | – | – | 24.50 | 25.70 | 24.40 | 23.90 | 45% | *** | <1% | ns | 9% | ns | |
| BBCH 19 | |||||||||||||||||||
| NUE_DM | g gN−1 | 11.29 | 10.80 | 57% | *** | 19.57 | 12.23 | 55% | ** | – | – | – | – | – | – | – | |||
| NUpE | gN gN−1 | 0.39 | 0.37 | 62% | *** | 0.59 | 0.47 | 22% | ns | – | – | – | – | – | – | – | |||
| NUtE | g gN−1 | 29.02 | 29.40 | 35% | * | 33.04 | 25.63 | 89% | *** | – | – | – | – | – | – | – | |||
| BBCH 30–32 | |||||||||||||||||||
| NUE_DM | g gN−1 | 23.62 | 24.30 | 15% | ns | 28.45 | 12.73 | 86% | *** | 12.40 | 17.15 | 6.90 | 7.24 | 18% | *** | 48% | *** | 17% | *** |
| NUpE | gN gN−1 | 0.68 | 0.71 | 6% | ns | 0.68 | 0.42 | 65% | ** | 0.33 | 0.44 | 0.31 | 0.27 | 20% | *** | 33% | * | 17% | ** |
| NUtE | g gN−1 | 34.86 | 34.10 | 64% | *** | 39.04 | 30.07 | 68% | *** | 37.20 | 38.70 | 22.30 | 21.30 | 5% | *** | 87% | *** | 4% | *** |
| BBCH 59 | |||||||||||||||||||
| NUE_DM | g gN−1 | 36.02 | 42 | 68% | *** | 38.88 | 30.55 | 42% | * | – | – | – | – | – | – | – | |||
| NUpE | gN gN−1 | 0.74 | 0.78 | 22% | ns | 0.84 | 0.74 | 33% | ns | – | – | – | – | – | – | – | |||
| NUtE | g gN−1 | 48.54 | 54.1 | 72% | *** | 46.39 | 40.76 | 40% | * | – | – | – | – | – | – | – | |||
| BBCH 68–71 | |||||||||||||||||||
| NUE_DM | g gN−1 | – | – | – | 70.83 | 33.74 | 99% | *** | 61.30 | 62.40 | 41.80 | 46.20 | 10% | ns | 44% | *** | 7% | ns | |
| NUpE | gN gN−1 | – | – | – | 0.83 | 0.74 | 60% | ** | 0.75 | 0.79 | 0.68 | 0.64 | 13% | ns | 7% | * | 9% | ns | |
| NUtE | g gN−1 | – | – | – | 85.42 | 46.00 | 98% | *** | 82.80 | 82.50 | 62.00 | 72.20 | 32% | *** | 50% | *** | 4% | * | |
| BBCH 84–89 | |||||||||||||||||||
| NUE_DM | g gN−1 | 59.20 | 66.50 | 55% | *** | 72.03 | 27.96 | 98% | *** | 68.20 | 70.40 | 42.03 | 43.05 | 11% | ** | 62% | *** | 3% | ns |
| NUpE | gN gN−1 | 0.70 | 0.74 | 36% | * | 0.75 | 0.51 | 94% | *** | 0.85 | 0.85 | 0.63 | 0.66 | 7% | ns | 57% | *** | 5% | ns |
| NUtE | g gN−1 | 84.25 | 86.70 | 52% | ** | 95.84 | 54.75 | 97% | *** | 79.70 | 82.90 | 67.10 | 65.10 | 30% | *** | 43% | *** | 4% | ns |
| NUE_Seed | g gN−1 | 14.72 | 15.92 | 62% | *** | 18.33 | 7.02 | 98% | *** | 16.20 | 14.20 | 10.80 | 10.40 | 16% | ** | 42% | *** | 9% | * |
| Seed Yield | t ha−1 | 2.48 | 2.70 | 61% | *** | 3.28 | 4.46 | 76% | ** | 2.29 | 2.02 | 6.29 | 6.03 | 3% | * | 85% | *** | 2% | ns |
Six key phenological stages were targeted: BBCH 16–18 (beginning of rosette growth), BBCH 19 (mid rosette development), BBCH 30–32 (beginning of stem elongation), BBCH 59 (just before flower opening), BBCH 68–71 (end of flowering), and BBCH 84–89 (seed maturity). For each stage, values of NUE_DM, NUpE, NUtE, and NUE_Seed represent the mean of all genotype samples cultivated under the same N condition in the same experiment (at each phenological stage, n = 30 in LR15 and n = 37 in GR18) and of AVISO alone (n = 5 in LR15, n = 7 in GR18, and n = 6 in GR15 at each phenological stage). The significance of genotype (G) (GR18 and LR15 only), nitrogen condition (N) (GR15 and LR 15 only), and genotype × N (GxN) interaction (LR15 only) effects was assessed for each experiment separately. Effects are expressed as a percentage of total variation (%var or, for LR15, variance decomposition). Significance codes:
P-value < 0.001,
P-value < 0.01,
P-value < 0.05.
NS, non-significant.