Discrete levels of desiccation sensitivity in various seeds as determined by the equilibrium dehydration method

Abstract

This study examined the hypothesis that desiccation sensitivities of recalcitrant and intermediate seeds can be categorized into discrete levels of critical water potential. The equilibrium dehydration method was used to determine the critical water potential (CWP) below which desiccation damage started to occur. The CWP values of Bruguiera cylindrica, Lansium domesticum, Litchi chinensis and Lumitzera racemosa are approximately ‐4 MPa. The CWP values of Andira inermis, Avicennia alba, Castanea sinensis (from New Zealand), Citrus aurantifolia, Ginkgo biloba, Nephelium lappaceum and Theobroma cacao (immature axis) are approximately ‐8 MPa. The CWP values of Acer pseudoplatanus, Castanea sinensis (from China), Quercus rubra and Theobroma cacao (mature axis) are approximately ‐12 MPa. The CWP values of Artocarpus heterophyllus and Hevea brasiliensis are approximately � 23 MPa, while the CWP values of Acer platanoides, Azadirachta indica, Carica papaya and Coffea arabica are approximately ‐73 MPa. Together with data available in earlier literature, these CWP values suggest that there are five discrete levels of critical water potential among desiccation-sensitive seed tissues. These data support the hypothesis that discrete levels of desiccation sensitivity occur among recalcitrant and intermediate seeds, and suggest that specific damaging and protective mechanisms exist at certain hydration levels.