Fig. 5.
Relationships between net assimilation, An, and stomatal conductance, gsw, in ‘Fuji’ and ‘Braeburn’ apple cultivars. Equation for ‘Fuji’: [An = (aA bA gsw)/(aA + bA gsw) + cA]; equation for ‘Braeburn’: (An = aA gsw + bA). Fitting parameters: ‘Fuji’: aA = 18·685, bA = 4·671, cA = –0·183 (R2 = 0·90); ‘Braeburn’: aA = 43·835, bA = 2·611 (R2 = 0·82). The covariance analysis, using gsw as the covariate, revealed significant differences (P < 0·05) between the cultivars for An. The mean An values followed by different letters were significantly different: ‘Fuji’, 10·06a, ‘Braeburn’, 8·84b. An and gsw were measured in sunlit and shaded leaves (n = 12 and 17 in ‘Braeburn’ and ‘Fuji’, respectively) under standardized environmental conditions: PPF = 1500 µmol m−2 s−1, Tl = 25 °C and VPD < 1·5 kPa.