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Titre :
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Measurement of water activity on forest tree seeds: an efficient tool for seed bank management
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Titre original:
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Mesure de l'activité de l'eau sur les graines d'arbres forestiers : un outil efficace pour la gestion des banques de graines
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Auteurs :
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P. Baldet ;
F. Colas ;
M. Bettez ;
CEMAGREF NOGENT SUR VERNISSON EFNO ;
ISTA Moisture, Forest Tree and Shrub Seed and Tetrazolium Workshop, Péri, 12-14 juin (2008; ITA) ;
MINISTERE DES RESSOURCES NATURELLES ET DE LA FAUNE DIRECTION DE LA RECHERCHE FORESTIERE QUEBEC CAN ;
MINISTERE DES RESSOURCES NATURELLES ET DE LA FAUNE CENTRE DE SEMENCES FORESTIERES BERTHIER CAN
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Type de document :
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article/chapitre/communication
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Année de publication :
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2008
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Format :
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42 p.
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Note générale :
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présentation power point de 42 diapos
Diffusion tous publics
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Langues:
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= Anglais
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Mots-clés:
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ACTIVITE DE L'EAU
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GRAINE
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SEMENCE
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ARBRE FORESTIER
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CONSERVATION
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STOCKAGE
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HUMIDITE
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CONTROLE DE QUALITE
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QUALITE
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TECHNIQUE DE LABORATOIRE
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POLLEN
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SECHAGE
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ESSENCE FORESTIERE
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CONSERVATION DES RESSOURCES GENETIQUES
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METHODOLOGIE
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MESURE
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Résumé :
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Water activity (aw) measurement is a non destructive, portable and rapid technique to assess moisture of hygroscopic materials. aw is very close to equilibrium relative humidity (eRH). Both are reliable indicators of the status of water in compounds like seeds because they are a function of the water potential (?) which is the energy status of water in hygroscopic matrixes. Gravimetric moisture content (MC) of a given sample is not a factor but a consequence of the combination of a given water potential and an unpredictable ratio of hygroscopic (starch, proteins..) and non hygroscopic (lipids) components. Water activity is used in routine by many seeds banks like the Millenium Seed Bank project managed by the Kew Royal Botanic gardens. aw is considered in this application as a non destructive assessment of seed moisture which can be turn into moisture content by reference to the sorption isotherm data. However, Cemagref demonstrated that sorption isotherms revealed, for forest materials, a significant intra-specific variability of resulting MC for a given aw or eRH, this finding seriously weakens the operational prediction and use of gravimetric moisture content from eRH or aw. This has been confirmed by the work conducted at the Direction de la Recherche Forestière (Québec) on boreal species. As a result, aw appears to be a particularly suitable moisture management technique for seed produced by species with high level of diversity like forest reproductive materials. Consequently, we consider aw as a valuable reference to qualify moisture status of seeds and resulting predictable stability versus chemical or biological hazards. Therefore, aw can be used as a very valuable tool for seed lot moisture management from collection to storage.
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