Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 2003
Publication Date: N/A
Interpretive Summary: Several different types of trees produce nuts that have been used by people around the world as food crops. As nut culture has spread, rootstocks have been selected to fit the challenges posed by new sites or new production systems. This paper reviews information about several types of nut producing plants: almonds, chestnuts, hazelnuts, pecans, pistachios, and walnuts. The history of crop production and the techniques of crop production are also briefly reviewed. Current practices of rootstock production and development are reviewed for each crop. The universal challenge of rootstock selection is to find the proper stock for a particular site, and to grow it in a way that contributes to the long-term life of the tree within the cultural system. By crossing related species, hybrids can be formed that may perform better on particular sites, or under certain cultural systems. Genetic diversity is needed to make the right rootstock selections and breeding combinations. Recently, there has been great international cooperation in sharing genetic diversity. Most breeding programs are using techniques of genetic analysis to help understand more about genetic diversity, which should help in developing better rootstocks.
Technical Abstract: The driving force behind the development of rootstocks for nut crops has been the solution of specific problems, often related to the presence of pests or the need for adaptation to particular sites. The use of interspecific hybrids as rootstocks has lead to increased appreciation for the contribution genetic diversity can make to orchard profitability in the face of site specific challenges. The past decade has seen dramatic increases in access to germplasm resources, while technological developments in molecular genetics have contributed to genetic characterization in some species. The focus on clonal propagation through tissue culture has been somewhat abated by the slow place of nursery incorportation of available techniques, by the challenges with anchorage of some clonal rootstocks, and by the recognition of the vulnerability inherent to a monoculture susceptible to an unsuspected root pest. Increased application of spatial analysis systems (GIS) may contribute to prescription use of site-specific rootstocks.