Seed Testing Methods

Seed Purity

A working sample of approximately 2500 seeds is sorted into Pure Seed, Inert Matter and Other Seeds, and the proportions expressed as percentages by weight. All seeds and other matter in this and a larger bulk search are identified.

Germination Test

Seed is grown on blotting paper or sand under controlled conditions of temperature, moisture and light for a set number of days. Seedlings are classified as normal, abnormal, hard (for legumes only), fresh or dead. Normal seedlings show the potential for continued development into satisfactory plants. Abnormal seedlings are damaged, deformed, unbalanced or decayed to such an extent that they would not be expected to develop into normal plants. Hard seeds are seeds remaining at the end of the test because they have not absorbed water. Fresh seeds have failed to germinate but are clean and firm and have the potential to grow once the causes of dormancy are removed. Dead seeds are neither fresh nor have produced any part of a seedling.

Seed Identification Test

Our seed laboratory has one of the largest specimen seed collections in the Southern Hemisphere and has highly trained and experienced staff able to provide a reliable seed identification service.

Seed Moisture Test

Seed is dried by an air oven method, and the loss of weight that occurs during drying is calculated as the percentage moisture content. Seed moisture content has an important influence on the retention of germination capacity during storage. Samples submitted for moisture testing must be sealed in a plastic bag prior to dispatch so that the moisture content does not alter during transit.

Seed Weight Test

Seed weight tests may be carried out on any seedlot, the results usually being expressed as 'thousand seed weight' (TSW) in grams. TSW information is useful in determining precision sowing rates for cereal and vegetable seeds, and to help distinguish between diploid and tetraploid seed lots of certain species (eg. Italian ryegrass and red clover).

Seed Vigour Test

Seed vigour tests are available for certain types of seed, where it is known that the test results are linked to the ability of seed lots to establish under stress conditions in the field, or survive in less than ideal storage conditions.

Buried Seed Test

Buried seeds can stay viable in soil for many years, causing contamination of crops with weeds or unwanted varieties. For this test, 5cm cores of soil are taken from a field and forwarded to the Laboratory where they are washed and seeds removed, counted and identified. Seeds can be germinated if required.

Tetrazolium Test

Tetrazolium tests provide a rapid assessment of the germination potential of a seed lot. It is a biochemical test in which living tissue is stained red while dead tissue remains colourless. Results are usually available within 24 - 36 hours.

Seed Health Test

Diseases carried by seed are known as seed-borne diseases and may be caused by pathogenic micro-organisms such as fungi, bacteria, viruses or nematodes (collectively known as pathogens). Pathogens are detected and identified in laboratory seed health tests.

Lolium Endophyte Test

The lolium endophyte fungus in perennial ryegrass pastures is closely associated with ryegrass staggers and resistance to attack by the Argentine stem weevil. A testing service for Lolium endophyte in ryegrass and fescue seedlots is available.

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