A seed bank is a special storage facility that keeps seeds from many plant species safe and dry. Scientists at the Royal Botanic Gardens in Sydney recently conducted an audit of their seed bank. An audit is a careful check to see if everything is in order. They wanted to know how many seeds were still alive and able to grow. This is important because seeds can lose their ability to sprout over time. The team used a simple test: they placed a small sample of seeds from each batch on damp paper and waited to see how many would germinate, or begin to grow. The results helped them understand which seeds needed to be replaced.

Temperature and moisture are two key factors that affect seed survival. The audit revealed that seeds stored at a constant temperature of minus 20 degrees Celsius had a much higher germination rate than those stored at warmer temperatures. For example, seeds of the endangered Wollemi pine showed a 95 percent germination rate when kept cold. In contrast, seeds stored at four degrees Celsius had only a 60 percent rate. This difference occurred because lower temperatures slow down the chemical reactions inside seeds. As a result, the seeds use up their stored energy more slowly and stay alive longer. Therefore, precise temperature control is essential for long-term seed storage.

Another finding from the audit was that seeds from different plant families do not all survive equally well. Seeds from the pea family, Fabaceae, often have hard outer coats that protect them. These seeds can remain viable, or capable of growing, for many decades. However, seeds from the orchid family, Orchidaceae, are tiny and lack stored food. They usually survive for only a few years in storage. This difference is caused by the seeds' physical structure. The hard coat of Fabaceae seeds blocks moisture and pests, while orchid seeds have no such protection. Consequently, seed banks must adjust their storage methods for each plant family.

The audit revealed that seeds stored at a constant temperature of minus 20 degrees Celsius had a much higher germination rate than those stored at warmer temperatures.

The audit also helped scientists decide which seeds to collect next. They found that some rare species had very few seeds left in storage. For instance, the native shrub Zieria prostrata had only 200 viable seeds remaining. Because this species is critically endangered, the team made it a priority to collect more seeds from the wild. They used GPS data to locate the remaining plants and carefully harvested new seeds without damaging the population. This cause-and-effect chain shows how an audit leads to action. By understanding the current state of the seed bank, scientists can plan future collections and ensure that rare species are preserved for generations to come.