Table 1.
SAM population phenotypes.
| Phenotype ID | Measurement method |
|---|---|
| Leaf Traits | |
| LA (leaf area) | Recently expanded leaves were scanned against a white background with a ruler in the image; images were transformed into binary (black/white) in Image J; area was measured with reference to the scale object using the Wand (tracing) tool |
| LMA (leaf mass per area) | Ratio of dry leaf mass to fresh leaf area (measured as above using a scanned image). After scanning (with a standard resolution of 300DPI), leaves were dried for at least 3 days at 60°C and then weighed |
| CHL (chlorophyll content) | Measured using SPAD-502 meter, Konica Minolta. The average of four measurements per pair of recently expanded leaves per plant was taken (absorbance ratio) |
| LNmassC | |
| (Leaf Nitrogen Composition) | A recently fully-expanded leaf on each plant was collected, scanned, and then dried at 60 °C to constant mass. The dry leaves were ground with ball mill to fine powder, then dried again at 60 °C before weighing out 2–5 mg for Nitrogen analysis with an isotope ratio mass spectrometer (PDZ Europa Integra, Cheshire, England), which estimates total elemental concentrations, in UBC Forestry Stable Isotope Facility. Nmass (%): mass-based nitrogen concentration |
| LN (leaf number) | Number of true leaves >2 mm long |
| Plant Architecture | |
| PH (Plant height) | The length along stem from the soil surface to the apex |
| SD (Stem diameter) | Measured at the first leaf node nearest base of stem with calipers; took the maximum from 3 measurements as many stems were not perfectly cylindrical |
| HD (Hypocotyl diameter) | Measured at base of stem above soil with calipers; took the maximum from 3 measurements |
| SB (Shoot biomass) | Harvested all above-ground biomass and placed into labelled paper bag(s). The plants were dried at ~60°C for at least 3 days, or until biomass reached a constant weight, then weighed (in g) |
| Roots traits | |
| ARN (Number of adventitious roots) | All new roots from hypocotyl longer than 1 mm were counted |
Detailed methodological description of the traits measured for the SAM population in a GWAS flooding experiment carried out by Gao et al. in 201917.