Planting Angle and Meristem Management Influence Sweet Cherry Canopy Development in the 'Upright Fruiting Offshoots' Training System

摘要

Upright Fruiting Offshoots (UFO) is a novel high-density training system for sweet cherry (Prunus avium L.) that produces fruit on multiple vertical leaders ("offshoots") arising from a cordon-like trunk. The promotion of sufficient upright shoot number and uniform shoot distribution during establishment are key to development of this training system. Trunk angle, meristem management (selective bud retention and removal), and cordon height at establishment were evaluated for influence on shoot number, shoot distribution, total shoot length, and early fruiting potential. At planting, trunk angles of 45 degrees or 60 degrees from the horizontal resulted in increased shoot growth compared with 30 degrees, and also increased shoot distribution when bud selection was not imposed. A cordon height of 45 cm increased total shoot length by 20% compared with a 60-cm cordon height. Bud selection (retaining buds for optimal upright shoot distribution and removing all others) improved canopy development by reducing the number of shoots in the terminal third of the cordon and increasing the number of shoots in the basal and middle thirds compared with no bud selection. Bud selection reduced fruiting potential in the 2nd and 3rd years compared with unmanaged treatments, but subsequently surpassed those treatments in projected annual yield in Year 4 and cumulative yield in Year 5. Bud selection increased total and average shoot" length, and improved distribution while moderating early crop load potential. Planting angle, cordon height, and bud selection significantly impact canopy establishment of UFO trees by affecting shoot number, length, and distribution.