Branching habit of 2-year-old pear branches classified on the basis of length and position of 1-year-old laterals

Abstract

Two-year-old branches of Pyrus communis L. were classified into groups according to the proleptic (from dormant buds) branching habit, indirectly quantifying the degree of apical control. In winter 1998 upright and flat, 2-year-old branches were randomly sampled from trees of seven pear cultivars, i.e., Forelle (on Quince A and BP1 rootstocks), Abaté Fetel, Flamingo, Packham’s Triumph, Golden Russet Bosc, Rosemarie and Beurre D’Anjou on BP1 rootstock. For each branch the length and position of the 1-year-old shoots on the 2-year-old axis was determined. Laterals were classified according to length (<1, 1–5, 5–20 and >20 cm) and position (distal to proximal quadrants on the 2-year-old axis); 16 classes in total. The number of shoots per length class per cm quadrant length for each cultivar was subjected to a cluster analysis, then a canonical and a stepwise discriminant analysis. The cultivars were grouped into four groups from group 1 (‘Flamingo’), which resembles a spurred growth habit with strong apical control, to group 4 (‘Packham’s Triumph’ and ‘Golden Russet Bosc’), which resembles a spreading growth habit and weak apical control. Groups 2 and 3 were intermediate. The gravimorphic influences on the branching habit were investigated.