Intermediate storage behaviour and the effect of prechilling on germination of Japanese Zelkova (Zelkova serrata) seeds

The small seeds of Japanese Zelkova, Zelkova serrata, seem to be orthodox seeds and have been treated as such by foresters. In this study, the responses of the seed viability of mature seeds to combined range of moisture contents (2%∼18%, on a fresh-weight basis) and subsequent hermetic storage at −20 to 15°C for 2 years were investigated. Among the three storage temperatures tested (15, 4 and −20°C) the seeds remain viable for at least 24 months at 15°C and a moisture content of between 2.1% and 10.5%. However, at 4°C seeds only remain viable at a moisture content of between 5.8% and 10%. Seeds stored at −20°C deteriorated the fastest and fewer than their viability was just 60% at a moisture content of 10.5%. Japanese Zelkova seeds survived at low moisture content; however, the viability was lost more rapidly than seeds with higher moisture contents. These results confirm that the storage behaviour of Japanese Zelkova seeds is intermediate between typical orthodox and recalcitrant seeds and is characterized as being tolerant of desiccation but sensitive to low and freezing temperatures.