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10-15% @ < 0°Ca
16 (12-20) weeks cold (c. 4°C)
Generally effective – although pretreatment durations, and numbers of repeat cycles may vary significantly between seedlots (dry slowly)Approximate date to initiate artificial pre-treatment (for 1 March sowing) 8 November
Intermediate – seeds that can only be partially dried or need very slow, careful drying. They deteriorate more quickly than ‘orthodox’ seeds but more slowly then ‘recalcitrant’ seeds.
Orthodox – seeds that can be dried without harm, and once dried can be frozen, stored for years with little deterioration and relatively easily revived.
Recalcitrant – seeds that cannot be dried or frozen and are therefore short-lived.
(?) – indicates storage characteristics are not yet fully understood.
a Maximum advisable storage c. 3years @ c. 10% moisture content & -10°C
Figures in brackets indicate that different seedlots often require different pretreatment durations. There are three potential courses of action:
Raising Trees and Shrubs from Seed (PDF-648K)
Forestry Commission Practice Guide 18.
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