Tree Physiology Advance Access originally published online on May 29, 2009
Tree Physiology 2009 29(8):975-987; doi:10.1093/treephys/tpp036
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Relationships among productivity determinants in two hybrid poplar families grown during three years at two contrasting sites
1 Research Group of Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk, Belgium
2 Corresponding author (Sophie.Dillen{at}ua.ac.be)
3 Department of Forest Environment and Resources (DISAFRI), Università degli Studi della Tuscia, Via S. Camillo de Lellis, 01100 Viterbo, Italy
4 INRA, Unité Amélioration, Génétique et Physiologie Forestières, BP 20619, Ardon, 45166 Olivet Cedex, France
 |
Abstract |
|---|
The objective of this study was to evaluate the environmental, temporal and genetic stability of the relationships between growth and a selection of tree architectural, leaf and phenological traits (selection based on the conclusions of previous studies carried out on the same experimental trial). Therefore, the growth of two hybrid families, Populus deltoides ‘S9-2’ x Populus nigra ‘Ghoy’ (D x N family, 180 F1) and P. deltoides ‘S9-2’ x Populus trichocarpa ‘V24’ (D x T family, 182 F1), was investigated during a 3-year period at two sites, i.e., in northern Italy and central France. At the end of the second growing season, all trees were coppiced and the resprouts were thinned to a single stem. At the end of each growing season, stem circumference and height were measured for all F1 hybrids. The number of sylleptic branches, individual leaf area (LA) and petiole length of the largest leaf along the main stem, production of new leaves, bud flush and bud set were estimated for a selection of genotypes (31 F1) per family at each site during the course of the 3-year experiment. The D x T family was clearly the most productive family and displayed the highest heterosis values. However, there appeared to be a compromise between good growth at a given site and stability between the two different sites, both at family and at genotype levels. Particularly, the less performing trees were stable between Italy and France. Among the studied growth components, the number of sylleptic branches and individual LA of the largest leaf along the main stem were the best growth predictors, irrespective of site and family. Growth strategies in terms of leaf development differed between the two families. Hence, leaf production rate was strongly associated with growth of the D x N family only. These results have important consequences for the use of the studied traits as selection criteria in breeding programmes.
Keywords: genotypex environment interaction, growth determinants, heritability, heterosis, petiole, phenology, Populus, syllepsis, time stability
Received December 17, 2008; Accepted May 7, 2009
* Present address: UMR 1137 INRA-UHP Écologie et Écophysiologie Forestières, 54280 Champenoux, France.