Propagation ability of selected walnut hybrids (Juglans regia L. × J. nigra L.)

Research on the possibility for walnut (J. regia) to be exploited as tree species suitable for forestry plantations, recently had a lot of impulses from the Italian Agricultural Ministry and, specifically, with the promotion of the Riselvitalia project. In the framework of the above mentioned project the "Istituto Sperimentale per la Selvicoltura" of Arezzo has developed a research aimed at the exploitation of some selections of a J. nigra population, identified in North Italy and characterized by a spontaneous inter-specific crossing ability with J. regia. The Persian walnut grows slowly with respect to J. nigra that, on the other hand, produces lower quality wood comparing to J. regia. Because of the difficulty in Juglans propagation, the "Istituto Sperimentale per la Frutticoltura" of Rome, due to its specific knowledge on grafting research of Juglans spp, was involved in the project. In the winter 2001 wood material was collected from the mother trees to test their propagating ability. Two grafting techniques were adopted: the Hot callusing in the winter and the Top grafting in the spring-summer. Wood-scion material collected from 20 (of the 23 selections) were grafted on walnut seedlings populations of "Bleggiana", "Monti Lessini", "Val Maira" and "Val Parma". Results were influenced by the poor phytosanitary condition of the mother plants and by the genotypes.