When walnut trees are planted for wood plantations, it is the common or European walnut tree (Juglans regia) that is used, suitable also for fruit production, whose seed in the best of cases comes from trees with suitable phenotypes for the production of wood. In most cases, however, the origin is unknown and this leads to the failure of the plantation. For this reason, not only phenology but also genetics is important to ensure transmission of characteristics to offspring and for them to be repeatable over the years.
In this sense, a law has been developed (Royal Decree 289/03 entered into effect in 2003, which transposes and adapts European Directive 1999/105/CE to Spain concerning the commercialization of forestry materials of reproduction) that makes it possible to guarantee both the genetic origin and quality of the materials used for plantations or reforestations. For the technicians responsible for certifying and controlling this material, as well as for the users of the seeds or seedlings, this law determines what the requisites are for authorizing the different types of base material, the conditions in which the seed or seedling must be produced, their characteristics, and the requisites for their commercialization.
The use of Juglans regia as a forestry seedling was difficult up until now because of the poor guarantees of origin and quality offered by existing materials in greenhouses. The interest, however, in establishing European or common walnut tree plantations for wood has turned out to be justified, due to the price of the wood, which is double that of black walnut or that of hybrids, and because it can be combined with fruit production and begin generating incomes in about the ninth year.
Taking the above into account, Cultivos Forestales y Micológicos, in collaboration with the Department of Mediterranean Tree Cultivation of the IRTA, set in motion in 2003 a project of selection of vegetal material of the native walnut tree for wood, with the aim of obtaining improved seedlings (or seeds) of Juglans regia and with the possibility of producing fruit.
Field work in establishing the clonal seed orchards.
We currently have seedlings of 3 clones of the common walnut tree, whose characteristics are detailed below.
Collaboration between the company and IRTA was frequent over the course of the project.
The clones of the common walnut tree come from a selection of native materials realized by IRTA chosen for their good characteristics and the quality of their descendants. These clones have been used to create a clonal seed orchard. The seed produced by this type of orchard brings improvements to the plantation: the characteristics for which the parents were chosen are known; the seed-producing trees, both masculine and feminine, can provide defined forestry characteristics, by which the obtained controlled seed produces improved, homogenous and repeatable progenies.
Clonal orchard that produces seeds to obtain a better growing J. regia.
The walnut tree is presented in a large volume, root ball container.
In favorable soils, J. regia can reach the same quality in the same time as hybrids (cycles of 25-30 years). In less favorable soils, the cutting cycle can be 5 to 10 years longer.
At the present moment, we offer the following clones:
MBSB-13, MBT-231. These are early sprouting clones and thus suitable to low, hot zones.
MBT-218. This is an intermediate sprouting clone.
The late sprouting MB7-1, MB7-2 clones, more suitable for cold, higher altitude zones with longer winters, are not yet available.
Walnut seedlings in the greenhouse (MBSB-13, MBT-231 clones).