Seed testing: why it's important for Australia's ecological restoration

This guest blog is contributed by Simone Pedrini from Curtin University.
 

When farmers buy seeds to grow their crops, those seeds have always been tested by an independent laboratory to check if they are alive, true to label and capable of germinating. A minimum quality is guaranteed.

Seed testing is so important to agriculture and food production because farmers, and society as a whole, cannot afford for crops to fail.

Some may argue that the restoration of degraded ecosystems is of equal importance. Yet, in Australia, little effort goes into assessing the quality of the native seeds used for direct seeding or nursery production.

The Australian native seed survey report (2020) provides useful insights into why this may be. While the procedure is valued and required by some suppliers and users, in most cases, it is either not required or considered too onerous to be justifiable.

Testing native seed is still a germinating field in Australia. Photo by Toby Peet.

What does seed testing involve?

Seed testing involves checking a representative sample of a seed lot to record the purity (the percentage of pure seed present), their weight per unit, and the presence of possible seed contaminants. Then the viability of the sample lot is assessed to establish the percentage of pure seeds that appear healthy and potentially capable of germinating.

Methods for checking viability vary, depending on available resources and equipment. For example, a low-tech assessment of seed fill can be achieved by using the cut test, where seeds are cut open with a scalpel blade to check the presence and health of the embryo and endosperm. A step up from that is conducting a germination test, and a more advanced method is a chemical stain test (soaking in tetrazolium to identify living tissue).

There are a number of ways to test seed quality, including the germination test shown here. Photo by Toby Peet.

How would seed or restoration practitioners use this information?

Access to seed testing results is incredibly valuable at all steps of the seed supply chain and seed-based restoration. For example, those results can provide valuable feedback on the timing for seed collection or harvesting in native seed production areas (SPAs), inform on the best methods to clean the seeds and best conditions for seed storage, and provide quality assurance to the customer. They can also be used to develop a more transparent and fair seed pricing system.

For restoration practitioners, seed quality information is vital when calculating seed mix composition and seeding rates for seed-based restoration.

Seed testing informs seeding rates for direct seeding and nursery production, helping maximise outcomes. Photo by Jesse Collins.

If farmers routinely get seed tested, why is it ‘either not required or considered too onerous’ to do the same for native seeds?

The testing of native seeds is unfortunately not always a straightforward and simple procedure. For a start, the majority of Australian species don’t have clear standards on how the test should be performed and how the results should be interpreted. By contrast, for crop, horticultural and forestry species, such parameters are unequivocally described by the International Seed Standards Association (ISTA).

Moreover, the high variability within a species, for example, of seeds collected from different plant populations (or the same population in different years), makes the development and application of standards difficult. Difficult, but not insurmountable: in more sophisticated native seed markets, such as in the Western United States, the testing of native seed batches is a routine procedure and is required when supplying public agencies.

A few more reasons why native seed testing is not widespread in Australia are the relatively high cost of testing in relation to the value of a seed batch, the limited availability of independent testing facilities and equipment, and the fragmented and mostly unregulated nature of the native seed supply industry in Australia.

While single suppliers might try to integrate seed testing into their procedures, it can be hard to justify the expense if customers don’t appreciate its importance and if the infrastructure and technology required to perform testing is hardly available.

Using tested seed is important to ensure seeding rates and mixes are optimised for ecological restoration success – but Australia needs to overcome barriers to make this an expected standard. Photo by Jesse Collins.

What can be done to make native seed testing more widespread in Australia?

A coordinated and broad collaboration between seed suppliers, research institutes, seed banks, seed testing labs and seed users is the key to driving the systemic change needed to modernise the industry and unlock the benefits that routine and widespread seed testing can provide to the native seed sector and seed-based restoration.

We are contributing to the effort with research that aims to provide baseline seed quality information for native seed batches commonly used for and produced by SPAs. We also aim to develop software for autonomous seed x-ray detection for faster and more cost-effective native seed testing.

This research is in the early stages, but what we learn will be shared with the whole industry to help support a future where native seed testing for ecological restoration is as valued and routine as seed testing for agriculture and food production.

Working together can unlock the benefits of seed testing for Australia’s ecological restoration. Photo by Jesse Collins.

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