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Desiccation sensitive seeds in New Zealand Long-term preservation of seeds under the standard conditions of seed banks (i.e. dried to equilibrium in a controlled environment of 5–20°C and 10-25% of relative humidity, and stored at a temperature of –18±3 °C and relative humidity of 15±3 %) is only feasible for orthodox (desiccation-tolerant) seeds (FAO, 2014). However, a large number of species cannot be preserved under these conditions, as is the case for species producing desiccation sensitive (recalcitrant) seeds.
About 20-25% of the seeded plants of the world produce non-orthodox seeds. But, since the proportion of recalcitrant seeds is habitat dependent, recalcitrance acquires greater importance in particular habitats, such as tropical evergreen rain forests. Here it has been hypothesized that ca. 47% of the indigenous flora may produce recalcitrant seeds (Tweddle et al., 2003; Daws et al., 2006).
As part of the collaboration between the New Zealand Indigenous Flora Seed Bank and the Royal Botanic Gardens, Kew, Massey staff member and NZIFN coordinator Jessica Schnell spent time working in the Millennium Seed Bank in the UK.
The aim is for Jessica to expand her curation and seed processing skills as well as experiencing seed collecting in the UK. Jessica has been following the banking process from arrival of the seed through to it being placed in the seed bank at -20°C.
The first job when the seed arrives at the seed bank is for the seed to be cleaned. The process begins with the seed being allocated a serial number. The next step is to assess if the collection is infested. For seed found to be infested, the relative humidity of the seed is tested and if it is found to be dry enough not be damaged by freezing it, then the seed is placed at -20°C for 1 week. Seed not infested goes straight into the drying room to bring down the moisture content of the seed to the low levels needed to maximise the seed storage life.
Treated seed can also be a potential hazard. Treated seed is handled in the dust-hood with heavy duty gloves. Cleaning is done by hand or with blowers rather than by machine to minimise damage during the cleaning process – damage that may reduce the seed storage life.
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Last updated on Tuesday 16 August 2016