Controlled deterioration was initially developed as a test for detecting seed lots of small vegetable species (carrot, onion, lettuce, brassicas) with poor field performance potential (Matthews, 1980; Powell and Matthews, 1981) and storage potential (Powell and Matthews, 1984a,b). Subsequent work has demonstrated the ability of this test to rank seed lots of a large number of species for potential performance (Hampton et al., 1992). The controlled deterioration test can consistently identify low vigour seed lots (Powell et al., 1984). Source: International Seed Testing Association, Handbook of Vigour Test Methods, 3rd Edition 1995.
Since then the test has seen much work on Canola varieties in Canada by Dr. Bob Elliot of Agriculture Canada. This work has shown excellent correlation between controlled deterioration results in the laboratory and field emergence.
Like the Accelerated Ageing test Controlled Deterioration subjects the seed to conditions of high moisture and humidity. These variables are known to cause rapid seed deterioration. Unlike the Accelerated Ageing test the seed moisture in a Controlled Deterioration test is kept constant. Seed lots with high vigour should be able to withstand these stress conditions and will deteriorate at a slower rate than lots with poorer vigour.
After moisture testing the seed and adjusting the moisture accordingly, the seed is sealed in foil packets and place in a specialized chamber with very precise temperature control for a deterioration period. After this the seed is quickly planted in normal standardized germination conditions. The closer the Controlled Deterioration number is to the Germination the better the vigour. Results are expressed as a percentage normal germination after deterioration (vigorous seedlings).
Crop species that have had controlled deterioration research conducted includes: Brassica spp., Sunflower, Beet, Pea, Clovers/Alfalfa, Carrot, lettuce, onion, and grasses.
Remember it is important to support all vigour tests with a germination result. Adequate germination is the first requirement in choosing seed lots.
Seed Check Technologies Inc. has seed technologists who have recent training in Controlled Deterioration testing from Matthews, Powell and TeKrony at the ISTA Vigour workshop in South Dakota June 2002.