Photosynthetic response to light levels is influenced by peach genotype/rootstock combinations

The photosynthetic activity of three peach genotypes, differing in size and habit (standard, semidwarf and dwarf) was compared under variable Photosynthetic Photon Flux (µmol m⁻² s⁻¹) (PPF) conditions. Trees were both grafted on GF677 and self rooted. The grafted peaches showed higher Net Photosynthesis (µmol CO₂ m⁻² s⁻¹) (Pn) values than those self rooted, although the incremental effect of the rootstock on the photosynthetic activity tends to diminish under reduced PPF conditions. Dwarf type showed the highest net photosynthetic ability both when self rooted and grafted, while the semidwarf peach showed a photosynthetic activity higher than standard peach only when grafted; in dwarf trees the rootstock affects the intercellular CO₂ concentration, conditioning the photosynthetic response to reduced PPF.