Submitted to: International Congress on Hazelnut Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 1, 2001
Publication Date: August 27, 2001
Interpretive Summary: Hazelnut seeds remain viable for less than one year using conventional seed-storage techniques. We developed a cryopreservation (frozen storage) protocol that can be used to store the seeds for hundreds of years. The process centers on the growing points that are referred to as the embryonic axis. The whole seed, or the axis removed from the seed, can be dried to 8-10% moisture without harm. At this moisture content freezing does not injure the axis. If the whole seed is dried and stored, the axis must be removed and grown in culture after thawing because the remainder of the seed is destroyed by freezing. Cultured axes can be grown into whole plants and transplanted to the greenhouse. A special pretreatment of the seed under cool moist conditions (stratification) must be used before cryopreservation if the seeds are held for more than a short time after harvest. Storage in liquid nitogen (-320oF) was highly successful for the five species tested.
Technical Abstract: Whole hazelnut (Corylus L.) seeds do not survive freezing in liquid nitrogen (LN2), however excised embryonic axes can with appropriate treatment Although freshly harvested axes are easily cryopreserved, secondary dormancy inhibits growth soon after harvest. A short stratification treatment of stored nuts followed by dehydration and LN2 storage was successful for long-term storage of hazelnut germplasm. Whole seeds dried to very low moisture contents were frozen and the embryonic axes survived LN2 exposure although cotyledons were badly damaged. Dried whold hazelnuts can be stored in LN2 if the axes are excised and cultured after thawing. This technique avoids the problems of cotyledon damage and subsequent contamination and death of whole seeds during germination. A two-week stratification of stored seed before excision of axes greaty improved growth and decreased callusing. Drying isolated embryonic axes to o8-10% moisture, either by laminar flow or over silica gel prior to freezing, produced high survival and shoot growth from stratified-stored Co rylus seed. C. americana Marshall, C. colurna L., C. heterophylla Fisch. Ex Trautv., and C. siboldiana Blume axes were prepared, cryopreserved, shipped to the National Seed Storage Laboratory in Fort Collins, Colorado, and stored in liquid nitrogen. This is the first base (long-term) conservation of hazelnuts in world germplasm collections. Seed of additional species will be added as they become avaliable.