© 1993 Heron Publishing—Victoria, Canada
Maturation of maritime pine (Pinus pinaster Ait.) seedlings after exposure to a period of continuous light
Denis Martin Lascoux (1, 2, 3), Eduardo Notivol Paino (4), Rosario Sierra de Grado (5), Antoine Kremer (2) and Ingegerd Dormling (1)
1. The Phytotron, Department of Forest Genetics, Swedish University of Agricultural Sciences, Frescati Hagvag 16 B, 104 05 -
Stockholm, Sweden / 2. Laboratoire de Génétique et d'Amélioration des Arbres Forestiers, INRA, BP 45, 33611 Gazinet Cedex, France / 3. Department of Forestry, University of Wisconsin, 1630 Linden Drive, Madison, WI 53706, USA / 4. Unidad de Anatomia, fisiologia y mejora genetica forestral, E.T.S. de Ingenieros de Montes, Ciudad Universitaria, S/N 28040
- Madrid, Spain / 5. Departamento de Sistemas Forestales, CIT - INIA, Carretera de La Coruña, 28040 - Madrid, Spain / Received April 14, 1992
Summary
Nine half-sib families of maritime pine (Pinus pinaster Ait.) of known adult performance were grown in continuous light at either 25 °C or 25/20 °C for 18 weeks. They were then
exposed to a dormancy induction period followed by a dormancy release period and then grown for a further 9 weeks in a 16-h
photoperiod at a day/night temperature of 25/20 °C. Seedlings exhibited great diversity in morphology at the end of the first
growth period. The number of morphogenetic cycles varied between one and three
and the form of the apical meristem ranged from a typical rosette to an adult-like bud. The type of seedling obtained at the
end of the first growth period strongly influenced later growth, independently of the temperature regime. Maturity was proportional
to the number of morphogenetic cycles achieved during the first growth period and was characterized by short growth duration,
small primary needles and a high degree of fixed growth. The state of the apical meristem that underwent the dormancy period
had less influence on the rate of maturation than the number of morphogenetic cycles. The time course of maturation was endogenously
controlled and varied among traits. Conspicuous morphological differences were not associated with changes in the relationship
between growth components at the phenotypic level. However, there seemed to be a shift in the genetic correlations between
growth components after
first budset.
Keywords:
apical meristem morphology, fixed growth, free growth, growth components, maturation, morphogenetic cycles.
