Effects of crop load and rootstock on fruit quality in 'Suncrest' peach cultivar

The project was set up in 2003 to investigate the effects of crop load and rootstock on fruit quality and tree yield in peach. The study was carried out in two areas of Italy (southeast Po valley, lat. 44.3 degrees N - 12.07 degrees E, 34 m a.s.l; Rome, 41.6 degrees N 12.4 degrees E, 20 m a.s.1), on mature 'Suncrest' trees grafted onto rootstocks of different vigour: GF677 (P. persica x P. amygdalus), Barrier1 (P. persica x P. davidiana), PSA5 (P. persica), Ishtara ((P. cerasifera x P. salicina) x (P. persica x P. cerasifera)). Three different crop loads (CL), i.e., number of fruits/trunk cross-section area (TCSA), were applied to each graft-combination: a standard crop load (SCL=1.5 fruit/cm(2) of TCSA); a light crop load (LCL=1.0 fruit/cm(2) of TCSA) and a heavy crop load (HCL=2.0 fruit/cm(2) of TCSA). For all graft combinations, higher CL caused significant yield/tree increases and fruit-weight reductions. However, Barrierl and GF677 were more sensitive than Ishtara and PSA5 to fruit load and, for the same CL, produced smaller fruits. GF677 and Barrierl significantly delayed harvest date, while Ishtara advanced it. Increasing CL from 1.0 to 2.0 negatively affected fruit soluble sugars and titratable acidity on trees grafted onto Barrier1 and PSA5.