The effect of the initial rate of drying on the subsequent ability of immature seeds of Norway maple (Acer platanoides L) to survive rapid desiccation

The viability of Norway maple seeds harvested at mass maturity (57.3% moisture content) was reduced from 100% to only 38% if dried rapidly (at 15% RH and 15 degrees C for 3 days) to 4.7% moisture content. In contrast, slow drying for 32 days (the optimum duration of several investigated) to 29.9% moisture content enabled 93% of the seeds to survive subsequent rapid desiccation to 3.5% moisture content. This is similar to the 95% viability shown by seeds harvested 40 days after mass maturity and then dried rapidly to 4.4% moisture content. However, fruits or seeds harvested at mass maturity and then held moist for 21 days also showed 94 and 91% viability after subsequent rapid desiccation to 3.8 and 3.3% moisture content, respectively. Thus a post-ovule-abscission programme is required before Norway maple seeds are able to tolerate rapid enforced desiccation to low moisture contents, but loss in moisture during this period is not essential to the development of desiccation tolerance.