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item Walters, Christina

Submitted to: Seeds International Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/11/2002
Publication Date: 5/11/2002
Citation: Medeiros, A. and C. Walters. 2002. Sensitivity of Araucaria angustifolia embryos to low water contents and temperature. 7th International Workshop on Seed Biology, May 11-19, 2002, Salamanca, Spain.

Interpretive Summary: This work contributes to the effort to extend to storage life of Auracaria angustifolia (Brazilian pine) seeds, a tree species important to the Brazilian forest industry. The work is done in collaboration with Embrapa Florestas. A. angustifolia seeds do not survive drying and so cannot be stored for more than 4 months. We have shown that the seeds can survive drying to fairly low water contents, if drying is completed quickly. This finding will lead to better storage protocols for this important, but extremely difficult to conserve, species.

Technical Abstract: A. angustifolia (Bertoloni.) Otto Kuntze seeds (Brazilian pine) limits our ability to conserve genetic resources of this important species in ex situ genebanks. As initial steps in developing storage protocols, we studied the interaction of water content and temperature on embryo survival. Embryos were excised from seeds and ¿flash-dried¿to water contents as low as 0.50 g water/g dry mass and then exposed to 20 degrees C, 0 degrees C, -5 degrees C and -18 degrees C for 4 hrs. Surviving axes greened and produced roots and shoots in culture within 14 days. Drying axes to 0.50 g/g had no measurable effect on survival of embryos exposed to 20 degrees C or 0 degrees C. Drying to 0.50 g/g, or no drying at all, was lethal to embryos exposed to -5 degrees C. However, embryos exposed to 1.0 g/g followed by a -5 degrees C exposure showed no measurable effects on embryo viability. Exposure to -18 degrees C was always lethal. Though extended storage experiments are yet to come, these results suggest that A. angustifolia seeds may survive medium term storage at 0 degrees C or -5 degrees C if water contents are optimized. Further, the high survival of embryos dried to 0.50 g/g suggests that cryopreservation using ultra-rapid cooling techniques may provide a method for long-term conservation of this important species.