Table 2.
Calculation of whole-plant N use efficiency (NAE) and its components based on Weih et al. (2011), and the acronyms used in this manuscript.
| Symbol (Unit) | Component | Calculation |
|---|---|---|
| NS (g plant−1) | N content in the initial seed (cutting or seed potato) | |
| N' (g plant−1) | Mean plant N content during entire growth period | ((Nmean(H1−H2) × t(H1−H2)) + (Nmean(H2−H3) × t(H2−H3)))/t(H1−H3) |
| Nmean(H1−H2) (g plant−1) | Mean plant N content during H1 and H2 | |
| Nmean(H2−H3) (g plant−1) | Mean plant N content during H2 and H3 | |
| t(H1−H2) (Day) | Period between H1 and H2 | |
| UN (g g−1) | N uptake efficiency | N'/NS |
| EN,yield (g g−1) | Yield specific N efficiency | DBTuber/N' |
| CN,yield (g g−1) | Yield N concentration | N yield/DBTuber |
| NAE (g g−1) | N accumulation efficiency | UN × EN,yield × CN,yield |
| DBTuber (g plant−1) | Tuber dry biomass at final harvest | |
| FBTuber (g plant−1) | Tuber fresh biomass at final harvest | |
| BAg (g plant−1) | Dried above-ground biomass at final harvest |
H1, H2, and H3 represent the first, second and third harvests, respectively.