Phenotypic and genotypic diversity of European chestnut (Castanea sativa mill.) in Slovenia -: opportunity for genetic improvement

Phenotypic diversity of 244 chestnut trees was investigated. They originate from the Mediterranean and from two continental regions in Slovenia. In 3 years of analyses, length, diameter, thickness and weight of fruits; length and width of hilum, the pellicle intrusion; shape and colour of fruits; and the embryony were dealt with. The continental trees have smaller fruits than the Mediterranean trees; their fruits show greater variability in shape and the pellicle intrusion is stronger. They also exhibit polyembriony more frequently and they rarely have darker stripes. The sample of 46 trees from all three regions was used for the comparison between the phenotypic and genotypic diversity which had been investigated by RAPD analysis. In both cases, the UPGMA method was used for the classification of the trees into groups. Six pomological clusters were established. The clusters I, II, III and V comprise only the trees from the continental part. The cluster IV comprises nine trees of the marron type from the Mediterranean and one KOZ1 tree with equal pomological characteristics but originating from the continental part. The cluster VI is composed of eight trees from the continental part and one RAV3 tree whose fruits are very small and it originates from the Mediterranean. The Jaccard's coefficient of similarity is used in order to evaluate genetic relations. On the RAPD dendrogram four clusters of trees are defined. The continental trees are divided into three clusters and exhibit greater genotypic diversity than the Mediterranean trees which form only one cluster. With the RAPD analyses the differentiation of the trees with regard to their pomological traits is determined in 60-90% of the cases. The outcome of the research point to the fact that the Slovene chestnut is a rich source of genetic diversity and is very suitable for further breeding purposes.