RELATIONSHIP BETWEEN TREE ARCHITECTURE, PHENOLOGICAL DATA AND GENERATIVE DEVELOPMENT IN WALNUT (Juglans regia L.)

In the Bistrica orchard (SE Slovenia) 840 walnut trees were observed in period 1993 – 1998. The trees are between eight and twelve years old. They are free grown and non prunned. They represent a part of the spontaneous walnut seedling population in Slovenia. The leafing time, vigour, height of the tree, trunk diameter, tree habit, branching density and fruiting habit were analysed and their influence on the generative development (time of the first flowers and yield appearance) of the trees were defined. Phenotypic correlations between all features included into the trial, are explained. Early leafing genotypes are high, with densely branching and large trunk diameter. The leafing character is also well correlated with the appearance of the first male flowers. Vigorous genotypes are taller than others and have a larger trunk diameter. Smaller and less vigorous trees are dense branching. They have a tendency to lateral fruitfulness. Erect trees have very sparse branching, a smaller height and a smaller trunk diameter. The growth habit is fairly correlated with the first yield appearance, too. Four most frequent patterns of branching structure and fruit setting were observed: terminal, lateral and two kinds of intermediate. Main morphologic features of each branching pattern will be described. In lateral bearers female flowers appear three years earlier compared to terminal bearers and only one year earlier compared to intermediate trees. Lateral types develop male flowers earlier and have better yield potential than the other two types.

IV International Walnut Symposium

A. Solar, M. Hudina, F. štampar

walnut (Juglans regia L.), spontaneous seedlings, breeding, tree architecture, phenology, generative development, phenotypic correlations