Hagberg Falling Numbers and Spring Wheat Seed Quality

Many of you encountered problems with Hagberg falling numbers being below the market acceptable threshold of 300 seconds for your 2019 spring wheat crop. Even while the grain looked sound and without any visible sprout damage, the HFN test came back well below 300 seconds. In turn, you may have considered or are considering saving the grain for seed as a way to save an input cost this coming growing season and add value to the otherwise severely discounted value of 2019 wheat crop. To that end, you probably ran a germination test already last fall.  More than likely the germination exceeded 95% immediately after harvest.  Unfortunately, it is unlikely that it will maintain that percent germination.

At harvest the grain has a certain amount of post-harvest dormancy.  This dormancy is an evolutionary adaptation to avoid germination and growing during the hot and dry summer months in the center of origin of wheat (an area known as the Fertile Crescent).  This post-harvest dormancy will normally wane over time.  Unfortunately, it can also be broken by repeated wetting and drying while still standing in the field.  Once the post-harvest dormancy has broken, enzymes are activated as germination gets underway.  Alpha-amylase is one of these enzymes and it breaks down the starch that is stored in the endosperm into oligosaccharides and eventually into simple sugars. Normally the embryo absorbs these simple sugars and uses them to grow.  Over time enzymes, however, degrade, thereby losing functionality.

This means that grain that broke dormancy last fall during harvest will lose vigor during storage over the winter months.  Eventually, this will lead to lower percent germination. It is therefore recommended that you repeat the germination test of any seed lot that had low HFN test scores but high percent germination later this winter or early spring. Any seed lot that has dropped 15% or more since last fall should probably be replaced.