Figure 4. Net CO2 assimilation (µmol CO2m-2s-1); stomatal conductance (mol H2O m-2s-1); and transpiration rate (mol H2O m-2s-1) for ‘Honeycrisp‘ apple trees on B.9, M.9, G.969, CG.4292, G.210, G.87, CG.5257, G.814, G.890 rootstocks measured in 2018. Error bars denote standard error (N=3). Different letters indicate significance differences among means determined using a Tukey‘s mean separation test (α=0.05).