Produzione legnosa e miglioramento genetico: variabilità delle caratteristiche del legno in cloni di ciliegio (Prunus avium L.)
Author(s)
Nocetti, Michela
Date Issued
February 26, 2009
Type
Doctoral Thesis
Abstract
The study concerns with the genetic improvement programmes of trees for valuable wood production. So far, breeding strategy have been mainly targeted to maximize acclimation/adaptation to specific environment conditions, tree growth and disease resistance, but it is not obvious that such strategy might lead to improvement of wood characteristics at the same time. Wood characterization is an important step considering that the main final purpose of arboriculture is the production of high quality timber.
Cherry clones sampled from two clonal trials have been tested. The analysed traits were: growth; stem shape; heartwood content and, deeply, physical and mechanical characteristics of wood.
The study followed three main steps: the investigation of trait variability, both within tree, within and among clones and between sites; the analysis of correlations between traits and the effectiveness of density as representative trait of the whole wood properties; microdensitometric analysis aimed to verify the possibility of early selection of genotypes. Moreover, some observations on the presence of the green vein (a very widespread chromatic anomaly in the European wild cherry) were carried out.
The results suggested the importance of the clone effect on the most of the analysed traits, revealing the presence of genetic control over both growth and wood traits. But, while the site was the most important source of variation for the growth traits, for the wood traits, most variation was detected within tree, rather than within or among clones or between sites. Within tree variability seemed to be due mainly to the heartwood / sapwood presence and the genetic control was lower on heartwood than sapwood properties, showing probably an high environmental control on the heartwood formation process.
The growth traits were correlated between themselves but not with the wood traits, leading to an ineffective selection based on the tree growth in order to improve either wood quality, but pointing out the possibility of a contemporary selection based both on growth and wood properties.
The wood density was confirmed to be the trait that best represent the whole wood characteristics.
The early selection seemed to be possible thanks to the high correlation between heartwood and sapwood properties and the high correlation between the density of the adult tree and the density measured at the cambial age of 5-6 years.
Finally, the presence of the green vein seemed to be influenced by the genotype (different clones showed different incidence of the green vein), but the environment played a very important role, as well. The green vein showed to be closely connected to the tension wood.
Additional information
Dottorato di ricerca in Scienze e tecnologie per la gestione forestale e ambientale
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