shorter than for germination. But, by how much? Are certain vigor tests better able to determine seed
vigor than others? If so, would this time frame vary according to the test result? What influence would
seed storage environment have on the validity of vigor test results over time?
Use of Standards
Neither the ISTA nor AOSA Vigor Test Handbooks advocate the need for standards when interpreting
the results of a vigor test. This quality control process needs to be encouraged when conducting vigor
tests for the following two reasons. First, a seed testing laboratory should have a standard seed lot for
which vigor test values are known that is either routinely or anonymously introduced into the testing
regime. Because seed vigor testing requires precise environments and analyst interpretations, these
standards identify when test results may be altered or “out of tolerance” due to conditions external to the
seed.
Second, standards can also be employed in comparing results among laboratories for difficult to
standardize tests. For example, the use of local soils in a cold test makes comparison of test results
among laboratories difficult because soils vary in their pathogen levels and water holding capacities.
Both of these factors have a major impact on cold test results. However, if the laboratories comparing
seed lots use the same seed standard, they might be able to express the results on a percentage basis
relative to the standard. Thus, a seed lot may have a cold test result of 35% and the standard may be
45% at laboratory A. At laboratory B, the cold test may be less stressful and produce results of 70% for
the seed lot and 90% for the standard. While these absolute values are different, they are the same when
computed on the basis of the standard seed lot (laboratory A: 35/45 = 0.77; laboratory B: 70/90 = 0.77).