Variabilité génétique des composantes de la croissance en hauteur du Sapin de Céphalonie (Abiescephalonica)

Abstract

The annual height increment of the shoot can be divided into two morphogenetic components: the number of stem units initiated in the bud prior to bud break and their mean length. Observations were made on the lateral shoots of 43 Abiescephalonica open-pollinated families from three provenances located in an experimental site in southern France. Genetic parameters of the two components were evaluated with an analysis of variance. Correlations both between components and with annual height increment were examined at the phenotypic, genotypic, and individual levels. Differences between provenances were the result of number of stem units and annual height increment. Number of stem units presented a very high heritability and was strongly correlated to annual height increment at all variance levels. Mean stem unit length appeared to be more dependent on environmental variations and was less closely correlated to annual height increment, especially when genotypic data were considered. This particular growth strategy could be the consequence of A. cephalonica's adaptation to a Mediterranean-type climate. Of the two components studied, number of stem units was a better genetic predictor of annual height increment. A negative correlation between number of stem units and mean stem unit length was made apparent at the phenotypic and individual levels and should be considered when using number of stem units as a selection criterium.