Assessing Genotype-Environment Interaction for Poplars and Willows on agricultural sites in short rotation coppice - Results from the Joint Research Project ProLoc

In the course of the ProLoc joint research project field experiments with three poplar and two willow clones in short rotation coppice management were established in a uniform design on a broad amplitude of site conditions, in order to quantify the influence of yield determining site factors. Based on 23 of these experiments, the influence of the genotype-environment interaction on the total biomass growth performance was investigated. Using a variance component analysis, the largest proportion of the total variance could be explained by the site factor, the variance explained by genotype-environment interaction is significantly lower and the proportion of the factor genotype is negligible. Following a two-phase trial series analysis approach, the individual experiments were evaluated by one-way ANOVA in order to identify the sites with significant differences in the yield performance of the clones. 13 out of 23 sites showed significant differentiation in the ranking of the clones. Out of these 13 sites, only five of them had an average yield above the overall average of 42.38 t(atro) ha(-1). The clonal and site-wise means of yield performance were subjected to a biplot analysis in order to check whether site units can be formed that have a comparable differentiating effect on the clones. The biplot analysis displayed a good approximation of the data structure; the results of the variance component analysis were confirmed. At locations with similar ranking of clone means, no significant trends could be identified for site characteristics that could cause this ranking. Differences between the genera of the clones occurred rather as tendencies.