How accurate are seed viability tests?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Seeds' viability tests give reliable results if properly made. Germination tests accurately reflect the germination power of the seeds. Water tests supply quick tests of density, but are not satisfactory. Tetrazolium tests provide precise measurement of cell activity. Various methods of testing the viability are good for different purposes.
Reliability is gained through proper use. Use at least ten seeds for the test to achieve statistical significance. Maintain uniform conditions of temperature and moisture. I test several lots of older seeds to verify results. A combination of methods, such as water and germination tests, yields the most useful results for seed vitality.
Germination tests can provide an accuracy of 90-95% if the proper protocol is followed. Germination tests show the actual sprouting, but they take time to perform. Water tests provide between 70-80% accuracy for such seeds as beans, for instance. Tests with tetrazolium provide 95-98% accuracy, but this test requires highly trained personnel. Select the germination test that will meet your needs, along with the kind of seed you are testing, to get the best results possible.
Germination Test
- Accuracy: 90-95% when properly controlled
- Strengths: Shows actual growth potential
- Limitations: Time-consuming (2-14 days)
- Best for: Final planting decisions
Water Test
- Accuracy: 70-80% for appropriate seeds
- Strengths: Immediate results (15 minutes)
- Limitations: Unreliable for small seeds
- Best for: Initial screening of large seeds
Tetrazolium Test
- Accuracy: 95-98% with proper technique
- Strengths: Reveals cellular viability
- Limitations: Requires dissection skills
- Best for: Scientific precision
Increase accuracy using the following methods: Test several lots of seeds originating from different sources. For the indeterminate values repeat tests or add tests. Take the temperature and the humidity during tests. I keep a very carefully written record which helps me to keep track of the yearly variations in the viability of my seeds.
Recognize that no test will give a perfectly accurate prediction about how seeds will perform in the field. Soil conditions and weather conditions determine actual germination, so the results of tests merely give "excellent indicators" under controlled conditions. However, the results can be used to determine the density of planting and seed selection. The success of your garden depends upon this knowledge and the use made of it.
Read the full article: Seed Viability Test Guide: Ensure Your Seeds Grow
