The Tetrazolium test is one usually used to test seed lot viability. This test can also be very useful in determining seed lot vigour. The test is basically carried out the same as the viability test but viable seeds are evaluated more critically into categories of High, Medium and Low vigour as follows:

High Vigour:

• Staining is uniform and even, tissue is firm and bright.

Medium Vigour:

• Embryo completely stained or embryonic axis stained in dicots. Extremities may be unstained. Some over stained/less firm areas exist.

Low Vigour:

• Large areas of non-essential structures unstained. Only one root stained (monocots) or extreme tip of radicle unstained (dicots). Tissue milky, flaccid and over stained.

A major benefit of the test is a very rapid estimate of the vigour of viable seeds. To achieve meaningful results, a very experienced Tetrazolium analyst must evaluate the test and precision of methods must be strictly adhered to. This test has been used extensively on cereal crops and results for field pea have shown good relationships with field performance. It is also used in soybean, cotton, corn, and large seeded legumes.

Remember it is important to support all vigour tests with a germination result. Adequate germination is the first requirement in choosing seed lots.

Crop species that have had accelerated ageing research conducted includes: Soybean, Brassica spp., Sunflower, Beans, Clovers/Alfalfa, Corn, wheat, and grasses. Seed Check Technologies has recently conducted its own in house research using the accelerated ageing test on Barley. Results in many cases predicted a drop in germination extremely accurately.

Seed Check Technologies Inc. has seed technologists who have recent training in Conductivity testing from Dennis TeKrony at the ISTA Vigour workshop in South Dakota June 2002.