Abstract Germination ability, equilibrium relative
humidity (eRH), and moisture content of ‘control’ seed
samples representing 183 rice accessions stored in the
active (2–4 C) and base (-10 C until 1993, then
-20 C) collections of the T. T. Chang Genetic
Resources Center were determined after storage for
20.5–30.5 years. Germination of seeds that had been
stored in the base collection was generally high
([70 %), whereas germination was more variable for
seeds stored in the active collection. Sampleswith lower
viability after storage in the active collectionwere likely
to have lower viability after storage in the base
collection. There were significant differences in the
moisture content-eRH relationship of the seeds depend-
ing onwhether the seeds had been stored in the active or
base collection. Based on re-test data for regular seed
samples regenerated in 1979–1980 and stored in the
active collection for up to 31 years, estimates of the time
for ability to germinate to fall to 50 %(p50)rangedfrom
54 to 997 years. For the same seed samples stored in
the base collection for approximately 31 years, ability
to germinate has been maintained and germination
increased due to improved procedures. The ability to
germinate of base collection sampleswas also generally
higher than that of ‘safety duplicate’ samples of the
same seed lots that had been sent to the National Center
for Genetic Resources Preservation, USA in 1981 and
stored at -18 C. This may have been due to uptake of
moisture either during processing for dispatch or as a
consequence of poor packagingmaterial. The results are
discussed in relation to long-term seed storage and
genebank management.