Fig. 3From: Changes of secondary metabolites in Pinus sylvestris L. needles under increasing soil water deficitRelationship between the first two principal components (PC1 vs. PC2) of the principal component analysis (PCA) computed on needle metabolic compound variation. Symbols correspond to control (triangle) or water-deficient trees (circle) and are color-coded according to each physiological phase: I, white; II, gray; III, black Back to article page