Scion architecture on dwarfing candidate pear rootstocks

As part of the search for an easy to propagate, precocious, dwarfing Pear rootstock we undertook a study to investigate the dwarfing mechanism of three rootstocks with different vigour, selected from a population of Pyrus communis ‘Old Home’ and ‘Louise Bonne de Jersey’ seedlings. A potted trial was established using a low-, medium-, and high-vigour pear rootstock and included Cydonia oblonga Mill. ‘Quince BA29’ and ‘Quince C’ as control rootstocks. Regular assessments of P. communis L. ‘Doyenné du Comice’ scion growth on the rootstocks was undertaken to build an understanding of the plant growth that leads to dwarfed trees. Scion primary axis extension terminated earlier in the season on dwarfing rootstocks than on high-vigour rootstocks, leading to smaller trees. Sylleptic branching of the scions favored spur development over extension shoots, with the low-vigour pear rootstock producing a lower incidence of branching. The scions first flowered 2 years after grafting, with scions on the low-vigour pear seedling and the ‘Quince BA29’ rootstocks bearing fewer inflorescences tree^‑1. However, when expressed relative to trunk cross-sectional area, no differences were found. Initial data suggest the dwarfing mechanism of these rootstocks may be similar to that of dwarfing apple rootstocks.