Fig. 1. Climate condition, leaf parameters and metabolite explorative analysis.

a–b Climate data during cultivation in 2011 and 2012. a Cumulative rainfall and rainy days (left y-axis), and soil humidity (right y-axis) one month before harvest. b Boxplot of relative humidity (RH) and temperatures (T). Significance by Student’s t-test: *, ** = significant at P ≤ 0.05, 0.01, respectively; ns, non-significant. c–d Product parameters and principal component analysis of leaf metabolites (PCA). c Histograms of head weights (left panel) and dry vs fresh weight ratios of leaves (right panel). Effects of genotype (G), year (Y) and interaction (G×Y) by two-way ANOVA are below each panel. *, **, *** = significant at P ≤ 0.05, 0.01 and 0.001 respectively; ns non-significant. d PCA biplot shows the spatial distribution of 30 hydrosoluble compounds in curly Domari and Myrna (D, M) and smooth Confiance and Flester (C, F) cultivated in Lazio in 2011 (subscript I) and 2012 (subscript II). Sugars (blue circles): GLC, Glucose; FRU Fructose, SUC Sucrose, KES Kestose, INUL inulin, CAR-T total carbohydrates. Amino acids (green): ALA Alanine, ASN Asparagine, ASP Aspartic acid, GABA γ-Aminobutyric acid, GLN Glutamine, GLU Glutamic acid, ILE Isoleucine, PHE Phenylalanine, THR Threonine, VAL Valine, CA Citric acid, AA-T total amino acids. Organic acids (red): FA Fumaric acid, MA Malic acid, LA Lactic acid, SA Succinic acid, TA Tartaric acid, OA-T total organic acids. Polyols (yellow): CI Chiro-inositol, MI Myo-inositol, QA Quinic acid, SI Scyllo-inositol, POL-T total polyols. Phenols (purple): CHA Chicoric acid, MCTA Monocaffeoyl tartaric acid, PHN-T total phenols. Others (dark grey): CHN Choline, ETA Ethanolamine, OTR-T total other compounds