New Rootstock Cultivars for Peach Influence Growth, Yield and Fruit Quality

Prunus interspecific hybrids and plum species have replaced P. persica as the preferred rootstock for peach in Europe and some regions of North and South America. However, compatibility, growth, and yield of these new rootstocks have yet to be assessed with many peach cultivars. 'Redhaven' peach was grafted to 24 rootstocks represented in 2 replicated trials near Clemson, South Carolina. These trials were planted in 2005 and 2009 on a Cecil gravelly, sandy loam with a pH of 5.0 (no pre-plant lime) and 6.4 (pre-plant limed), respectively. The rootstock cultivars included 9 interspecific Prunus hybrids and 3 non-peach Prunus species. Growth, phenology, fruit maturity, fruit quality, and yield were collected annually. Significant differences among rootstocks were observed for growth, fruit maturity, yield and fruit quality attributes. Vigorous rootstocks were Viking, Atlas, BH-5, Empyrean (R) 1, Guardian (R) and Replantpac. The most dwarfing rootstocks included Krymsk (R) 1, Controller 5, P. americana, Fortuna and HBOK 32. Fortuna showed incompatibility symptoms. Trees on Imperial California were very susceptible to bacterial canker. Plum hybrids and species advanced maturity by 2-5 days. Yields in the early years were positively associated with tree vigor except for Fortuna, which yielded poorly. Yield efficiency was low for Empyrean (R) 1 and high for semi-dwarfing and dwarfing plum rootstocks and HBOK 32. Fruit size averaged >185 g for all rootstocks. There were small differences in fruit soluble solids among rootstocks with those of plum parentage having higher levels and fruit from trees on Krymsk (R) 1, Fortuna and P. americana having the highest Brix readings. No rootstock has emerged as the best at this time, though many appear adaptable to the local climate and soils.