Corn germination testing

I did blog on 3/3/16 about corn germination testing but perhaps it needs to be addressed some more.  It is a more difficult subject than would seem on the surface.  Seed companies are required to state on the bag or box tag the germination percentage based upon a warm test and the month the test was performed.  State laws may vary a bit but I think most require that the germination be done within 6 months of planting in the field.  This requirement is good in that it provides some guidance to the grower and the seed company.  There are some potential misleading aspects to this system. The seed laws also allow some variance due to sampling that, in reality, allows a warm test result of 89% to be legally tagged at 95%.  Also, seed with a warm test result of 100% be labeled at 95% on the tag. The variance is necessary but it would be a disadvantage to the seed company and grower to have a 95% tag on seed that only had an 89% warm test, but it would be legal.  I doubt that this is ever intentionally done.
 
The other enigma with the germination on the tag is that the warm test is usually not the best predictor of field emergence. Generally, the cold test is a better indicator of field emergence but the range of results among labs on cold tests is even greater than warm tests. Publishing cold test results by companies to the customers also requires a pretty long dialogue on the meaning.  Throw into this mix the problem of adequately sampling a large seed lot and potential affects of damage in shipping and on farm storage on germination.  Seed quality is one of the factors affecting plant emergence in the field. Studies of corn with acceptable range of germinations that I have seen over the years indicate that up to about 70% of the final stand in the field can be due to seed quality. Plant densities are only one of many factors influencing final grain yields. However, if reduced stands or uneven emergence did result in some yield loss, it may lead to the errant conclusion that the hybrid genetics were poor. Consequently, the grower switches hybrids for the wrong reason and the seed company has inventory problems the following year for the wrong reason.
 
We want things to be simple but that rarely is true when dealing with the plant biology and environments of agriculture.