Figure 8. The relationship between CO2 assimilation (µmol CO2 m-2s-1) and leaf δ13C isotope (‰) (P <0.01, r = 0.873); relationship between stomatal conductance (mol H2O m-2s-1) and leaf δ13C isotope (‰) (P <0.01, r = 0.807); relationship between transpiration rate (mol H2O m-2s-1) and leaf δ13C isotope (‰) (P <0.05, r = 0.787) for ‘Honeycrisp‘ apple trees on B.9, M.9, G.969, CG.4292, G.210, G.87, CG.5257, G.814, G.890 rootstocks. The lines indicate the adjusted linear regression for the combined data points.