Figure 3.

Principal component analysis (PCA) ordination diagram. The biplot displays the treatments (samples) at various times (6 d—day 6, 12 d—day 12, 22 d—day 22) with measurements of (a) photosynthetic assimilation of CO₂ (A), substomatal concentration of CO₂ (Ci) and stomatal conductance (gs); the first axis accounts for 77.7% of the variance and the second axis shows 20.4% of the variance; (b) proline and MDA content in leaves of P. oleracea and leaf water potential (ψw); the first axis accounts for 76.8% of the variance and the second axis is responsible for 21.7% of the variance. The treatments are indicated by the colors of the shapes: black circles, control; light blue squares, 100 mM NaCl; green diamonds, 300 mM NaCl.