Change over time of branching defects in corsican black pine (Pinus nigra ssp. laricio var. Corsicana) of Central France Provenance

Abstract

Change of branching defects over time was studied in a progeny test of. A sample of 337 trees was measured seven years after their first evaluation (ages 9 and 16). The change in the frequency of forks and ramicorns over time, and the influence of different whorl traits on these changes were studied. The percent of forks and ramicorns that could be recognised at age 16 was only 31.6 p. 100. About 55 p. 100 of ramicorns disappeared, due to the flattening of the branch angle with time. Trees with stable ramicorns were characterised by a narrow initial branch angle, a high level of polycyclism on branches and a large branch diameter. With time and diameter growth of the stem, the supplementary whorls on polycyclic branches may be progressively inserted in the stem before natural pruning occurs, resulting in a big local defect. Consequences for early selection are discussed.