Pre-harvest sprouting is a serious grain quality concern for millers and farmers alike. Sprouting is when the seed breaks dormancy and creates enzymes to begin breaking down kernel starch. As this process continues, the grain’s value to millers greatly diminishes. Pre-harvest sprouting is more likely to occur where there is frequent rainfall and high humidity once the grain reaches maturity. Additionally, cold shock during grain development can lead to pre-harvest sprouting.
Falling numbers is a test that indicates how well the grain’s starch has retained its strength. To conduct the test, you must grind the grain into meal, add water, mix with a stirrer and add heat for 60 seconds. Heat activates the starch to produce a thick, gelatinous consistency. Thin consistency indicates that the starch has already been degraded. The falling number is the number of seconds it takes for the stirrer to fall to the bottom of the test tube. The longer it takes the stirrer to fall, the higher the quality of starch (longer chains). If it falls quickly, that is an indicator that alpha-amylase enzyme may be at high enough levels to start the starch degradation process for seed germination. Millers prefer wheat testing above 300 seconds. Discounts begin at levels less than 240 to 260, depending on the year, the elevator and the needs of the end-user. Wheat with low falling numbers may only be able to be sold as livestock feed.
It became apparent early in the 2017 wheat harvest that falling numbers was a problem in some areas of Michigan. Therefore, samples were collected from the Tuscola County state yield trial location and tested for falling numbers at Michigan State University’s Cereal Milling and Product Laboratory by Schae-Lee Olckers. Results are listed in the table below. All varieties were located in the same field, so weather conditions should be fairly consistent and not the cause of variability between varieties. This information is valuable in determining which varieties are better able to resist sprouting. When selecting varieties, use multi-year data from multiple sources.
Source: Michigan State University