Our quality assurance program ensures that our customers know exactly what they are paying for and maximises the chance of on-ground success. The dot-points to the left outline how we achieve this. While we take many of these steps as a matter of course, we can design a tailored quality assurance program for specific projects involving diversity targets, purity targets, viability targets and so on. Below is some more detail on just a couple of aspects of our quality assurance program.
Seed Viability and Purity
Native plant seed comes in a variety of forms. Many species are are available as pure seed (e.g. Acacias) while others such as Eucalypts are normally supplied as a seed/chaff mix. Much of the native grass material available on the market is in floret form and usually contains a percentage of non-seed material. The percentage of non-seed material tends to be very variable depending on season and harvesting method. We conduct seed counts per gram of material for all our stock. When combined with the results of seed viability tests (which are usually conducted on samples of pure seed) we are then able to provide an accurate figure on the number of viable seeds per gram of material in the form it is supplied. This is the only meaningful number for species supplied in non-pure form such as most grasses and many others.
We have built up an extensive database of this information over time, giving us insight into the natural variability in seed count and viability of various species, how long it can be stored without significant reductions in viability, and ultimately an indication of what viability numbers actually represent a quality sample. This last point is critical for two reasons. Firstly, given that native seeds are a wild product subject to large variation in viability among samples, without this knowledge there is no way of knowing whether a viability of say 30% represents a low or high quality sample: for some species this would be the maximum we could expect, for others it would represent very poor quality seed. The second point is that armed with this knowledge we are able to nominate minimum viability benchmarks for many of the species we supply. This means that not only can we guarantee the viability of a given batch, but for specific long term projects, we are prepared to guarantee a minimum viability benchmark for bulk seed derived from many batches over periods of several years.
Seed Heat Treatment
Most practitioners simply follow the recommended treatment of soaking the seed in 100 degrees Celsius for 60 seconds. However our own trials revealed big differences in germination depending on the precise technique used. For each species we applied five different treatments and then had each batch tested for germination in an accredited laboratory. The results showed dramatic differences between treatments. Some examples of the range from worst to best treatment (% germination) are: Acacia decora 69-93%; Acacia falcata 43-86%; Acacia salicina 35-73%; Hardenbergia violacea 60-81% and Indigofera australis 17-63%. In other words on average, 35% of seed can be wasted (either under-heated so it is still dormant or over-heated so it is dead) without the expertise and experience required to treat seed optimally.