Collection and Care of Acorns
The fruits of the genus Quercus are single-seeded nuts (Olson 1974). The biological characteristics of these nuts are different from those of most seeds, and these differences present acute problems in the collection and care of these fruits. Oaks of the United States belong to a group of species called "temperate recalcitrants." They are "temperate" because they grow primarily in the temperate zone; they are "recalcitrant" because their seeds do not tolerate desiccation below a critical moisture content (approximately 25 to 35 percent). Seeds of other species, which can be desiccated to below 10 percent, are called "orthodox," which means that they behave nicely when desiccated and survive long periods of storage under proper conditions. The "orthodox" group contains all temperate zone conifers, and many important hardwoods, such as ash (Fraxinus spp.), black cherry (Prunus serotina Ehrh.), yellow-poplar (Liriodendron tulipifera L.), sweetgum (Liquidambar styraciflua L.), and sycamore (Platanus occidentalis L.). (Bonner, 1993)
Acorns are the most difficult of all temperate zone American seeds to collect and care for properly. Most of the problems are related to the naturally high moisture content of these seeds and the need to maintain those moisture levels to maximize seed quality. Desiccation during collection and transport must be avoided; a 5 percent loss of moisture can harm acorn quality. Acorns of many species can maintain viability for up to 3 years if they are stored a few degrees above freezing with high moisture contents and some gas exchange allowed. If seed managers recognize the moisture considerations and plan for their impact, loss of acorn quality can be minimized. (Bonner, 1993)
The purpose of this section is to review the crucial steps in collection and care of acorns, and to present the best current recommendations on how to collect good acorns and maintain their quality. Every step of this process is heavily influenced by the moisture relations and recalcitrant nature of acorns. (Bonner, 1993)
Encyclopedia ID: p2166
