ISHS Acta Horticulturae 442: III International Walnut Congress
FIELD EVALUATION OF JUGLANS REGIA SELECTED CLONES FROM SEEDLING POPULATIONS OF MEDITERRANEAN AND ATLANTIC SPANISH COAST. |
| Authors: | N. Aletà, A. Ninot |
| Abstract:
In the Iberian Peninsula there are still more than 500.000 scattered J. regia seedling trees in the countryside (MAPA, 1993). In 1982 we started exploring local walnut populations of the Mediterranean coast, particularly in Catalonia, looking for material showing some useful traits as variety or genitor. Later, in 1988, we began a new survey in the northwest of Spain, Galicia, where there are many walnut trees and its climatic conditions are favorable to blight development. In this case we looked for trees more tolerant to blight than commercial cultivars. Pre-selected material has been studied for two years in its original place and, after that, the best individuals are grafted and planted in a field collection in Mas Bové, Tarragona, for comparing to reference cultivars. We have studied the main characteristics of the pre-selected material, 40 clones from the Mediterranean coast and 32 from the Atlantic coast. Isoenzymatic characterization, using four systems (MDH, PGM, SDH and 6PGD), showed the same five variable loci but their allele frequency is different. Vegetative and agronomic features showed some remarkable differences. Budbreak occurs earlier in the Mediterranean coast trees than in those from the Atlantic coast. Spread growth habit is more common in the Atlantic origin and the vigor looks like to be higher in seedling trees from the Mediterranean area. This last feature seems to be related to the plant material origin. The Atlantic coast clones have a high proportion of trees showing intermediate flowering (as ‘Hartley’) and this material is more tolerant to blight than that from Mediterranean area, mainly on leaves. | |
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