Table 2. Relationship between sunflower vigor under control conditions, salinity tolerance, and correlated suites of size-independent and ionomic traits.
R2 and significance of the ordinary least -squares regression of the PC1 and PC2 values of the size-independent and leaf ionomic traits (chlorophyll content, fine root allocation [mass fraction and root fraction], LMA, leaf mass fraction [LMF], RMF, SMF, tap root allocation [mass fraction and root fraction]) and elemental traits (B, Ca, Cu, Fe, Mg, Mn, N, P, K, Na, S, Zn, K/Na ratio) in control (0 mm NaCl) and salt-stressed (100 mm NaCl) conditions, as well as the plasticity in trait values between both environments (see "Materials and Methods" for details). Highlighted in bold are the top two regressions with the highest explanatory power for vigor and tolerance For elemental traits stars indicate significance of a t test between control and salt-stressed groups (*P < 0.05, **P < 0.01, and ***P < 0.001).
| Trait Set | Treatment | PC Axis | Vigor | Tolerance |
|---|---|---|---|---|
| R2adj. | R2adj. | |||
| Size-independent traits | Control | PC1 | 0.27*** | 0.02* |
| PC2 | 0.03** | – | ||
| Salt | PC1 | 0.08*** | 0.02* | |
| PC2 | – | 0.04** | ||
| Plasticity | PC1 | 0.02* | – | |
| PC2 | – | 0.17*** | ||
| Ionomic traits | Control | PC1 | 0.1*** | – |
| PC2 | 0.22*** | – | ||
| Salt | PC1 | 0.02* | – | |
| PC2 | – | 0.14*** | ||
| Plasticity | PC1 | 0.06*** | 0.04** | |
| PC2 | – | 0.04** |