Effects of Size-Controlling Rootstocks on Growth and Yield of Peach Trees with Upright and Spreading Growth Habits

Abstract

New genotypes of peach with upright, narrow canopies have been developed that have novel management challenges but high production value. While these novel genotypes are easily adapted to high density planting systems the increased tree height of narrow canopies can present problems in maintaining bearing surface low in the canopy, in harvesting, and the need for additional pruning. Size-controlling rootstocks have been used to manage tree size and productivity in apple and new size-controlling rootstocks have been developed for peach. These rootstocks may be highly beneficial for upright peach trees. In this experiment two Controller rootstocks (C5 and C9) and two standard (STD) rootstocks (Tennessee Natural and Bailey) were used with the cultivars 'Sweet-N-Up' (SU), which has an upright growth habit, and 'Redhaven' (RH), which has a standard spreading habit, to evaluate effects of rootstock on scion growth and yield. Trees on C5, C9, and STD were planted at 2.4, 3.0, and 4.3 m spacing, respectively. Training of SU and RH was to Quad-V and Open Center, respectively. Over the five years of this experiment, individual tree yield and average fruit size of SU was consistently greater than RH. Trees on C5 and C9 produced fewer fruit per tree than on the two STD rootstocks. However, yield (kg·ha-1) of all rootstocks with either cultivar was not different when adjusted for tree planting density. Yield per tree and individual fruit weights were most reduced on C5 rootstock and least on STD. In general, the smallest-to-largest trees grew on C5, C9, and STD rootstocks. SU or RH trees grafted on C5 and C9 rootstocks and planted at higher density had equivalent yield per hectare as trees on STD at low planting density. However, the trees on dwarfing rootstocks planted at higher densities may be economically advantageous due to reduced pruning and harvesting costs and the increased potential for mechanized orchard operations.