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ISHS Acta Horticulturae 1303: XIII International Pear Symposium

Effects of tree density, tree shape, and rootstock on 'Bosc' pears

Authors:   J. Lordan, P. Francescatto, T. Robinson
Keywords:   crop efficiency, pear, Pyrus communis, vigor, yield, yield efficiency
DOI:   10.17660/ActaHortic.2021.1303.24
While the adoption of high-density pear orchards during the last decades has resulted in a significant improvement in yield and fruit quality, there is great disparity of opinion on the optimum density or the optimum tree shape. In addition, the lack of precocious Pyrus rootstocks means that full production is often achieved many years after orchard establishment and remains one of the main challenges in pear production. A field trial was planted in 2013 at the New York State Agricultural Experiment Station in Geneva, New York, being part of the NC-140 project. This trial compares 3 systems (Tall Spindle, V-trellis and Bi-Axis) using three spacings (0.93.7, 1.43.7, 1.83.7 m) and three rootstocks (OHF69, OHF87 and Pyro2-33) with 'Bosc' as the scion cultivar. Bigger trees were observed for Bi-axis than either Tall Spindle or V-trellis. Tree size was significantly affected by spacing. Smaller trees were observed at 0.9 m, followed by 1.4 m, and the largest trees at 1.8 m. Regarding rootstock, bigger trees were on OHF69, followed by OHF87, and then Pyro2-33. Fruit weight was affected by tree spacing and rootstock. The wider the spacing the larger the fruit, whereas the smaller fruits were on OHF87 and the largest on Pyro2-33. Higher crop load was observed on the TS and V-trellis compared to Bi-axis. OHF69 rootstock had lower cumulative crop load than either OHF87 or Pyro2-33. In terms of cumulative yield efficiency, Pyro2-33 had the highest value, followed by OHF87, and then OHF69. There was a significant interaction among training system, spacing, and rootstock for cumulative yield. The highest cumulative yields were for Tall Spindle on OHF87 at 0.9 m (70 t ha‑1), followed by V-trellis on OHF87 at 0.9 m (67 t ha‑1), and Bi-axis on Pyro2-33 at 0.9 m (62 t ha‑1). The lowest cumulative yields were for TS on OHF69 at 1.8 m (29 t ha‑1), Bi-axis on OHF87 at 1.4 m (28 t ha‑1), and V-trellis on Pyro2-33 at 1.8 m (27 t ha‑1).

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