Resumo

TORRES, Cristian; PUNTIERI, Javier  e  STECCONI, Marina. Comparative study of annual shoot growth and branching in two species of Nothofagus (Nothofagaceae) and inter-specific hybrids. Bol. Soc. Argent. Bot. [online]. 2009, vol.44, n.3-4, pp.287-303. ISSN 1851-2372.

Main and secondary branches are more or less differentiated according to the species and this could be observed during the primary growth of the shoots that produce them. In young-adult trees of Nothofagus obliqua, N. nervosa and hybrids between them growing in a common garden, growth dynamics, size and morphology were compared between two distal shoots produced by main branches: one of these shoots continued the extension of the main branch whereas the other initiated a secondary branch. The two distal shoots differed from each other more notably in N. nervosa and in the hybrids than in N. obliqua. Despite the environmental homogeneities at the nursery and the common geographic origin of the individuals of N. nervosa and the hybrids, there were phenological and morphological differences of these entities. Growth duration and rate and final shoot length were largely variable within each entity. The variation between entities regarding axis differentiation could indicate differences in their capacities to use the surrounding space. The differentiation between main and secondary branches would start at the bud stage. Intra-specific phenological and morphological variation could be useful in artificial selection programs.

Palavras-chave : Annual shoot; Primary growth; Axis differentiation; Hybrids; Nothofagaceae; Nothofagus nervosa; Nothofagus obliqua.

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