Relation between growth and morphological traits and genetic parameters of Robinia pseudoacacia var. monophylla D.C. in northern Greece

The relation between growth and morphological traits, and genetic parameters were studied in a progeny test of 14 open pollinated families of the black locust monophylla variety (Robinia pseudoacacia var. monophylla D. C.) established in northern Greece in 1991. Measurements included height and dbh for 5 consecutive years, number and size of leaflets per compound leaf in 1991, thorns in 1992 and 1993, and trunk form in 1993. Data were subjected to analysis of variance while heritabilities and phenotypic as well as genetic correlations were estimated. It was found that the 14 families had a high growth rate during the study period but differences began to be insignificant for height in 1995 and dbh in 1993. The ratio of family coefficient of variation to coefficient of variation was 1/3.6. Individual heritability was higher for dbh than for height while family heritability was higher than individual one in both traits. Number of leaflets per compound leaf ranged from one to 27 and the size of thorns from 0 mm to 25 mm. The variation was much smaller within families for both leaflets and thorns. On the basis of leaf morphology and thorns two types of trees were distinguished: oligophyllous, with few but large leaflets and small thorns, and polyphyllous with many but small leaflets and long thorns. Most of Pearson correlation coefficients between the various growth and morphological characters were statistically significant, but only a few of them were high enough to explain a fair amount of the variation between the various characters. On the contrary, the correlations between height and diameter were much higher while the genetic correlations between various ages of the same factor were positive and indicate their value for early testing and selection.