Submitted to: Journal of the American Society of Brewing Chemists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2006
Publication Date: 7/15/2007
Citation: Henson, C.A., Duke, S.H., Schwarz, P., Horsley, R., Karpelenia, C.B. 2007. Barley seed osmolyte concentration as an indicator of preharvest sprouting. Journal of American Society of Brewing Chemists. 65(3):125-128.
Interpretive Summary: Severe economic losses can occur when cereal crops, such as barley and wheat, that are ready to be harvested are rained upon. Under these conditions the seeds will germinate in the field while still attached to the mature plant. These seeds are said to be "preharvest germinated". These seeds will not re-initiate germination after harvest. Hence, those industries that require seeds to germinate or require that seeds not be germinated will not purchase preharvest germinated seeds. These industries include the those involved in malting, brewing, baking and milling. Farmers who produce preharvest germinated seeds lose all market-place premiums and sometimes cannot sell the crop at all. The currently used method of measuring preharvest sprouting relies upon a visual inspection of the seeds. This method is laborious and prone to error depending upon the degree of training of the inspector. The research we report was designed to evaluate a potential new method of quantifying preharvest germination that is easy to conduct, reproducible and less prone to human error than the currently used standard method. The method we developed quantifies preharvest germination on a linear scale using a vapor pressure osmometer, an inexpensive portable device, and is comparable to the standard method in its sensitivity. Also, this method requires only minimal operator training. The impact of this research is that an improved method of quantifying crop damage damage due to pro-harvest sprounting is now available for use by those who produce and process small grains.
Technical Abstract: This study was conducted to test the hypothesis that barley seed osmolyte concentrations can be used as an indicator of preharvest sprouting (PHS). Osmolyte concentrations from the 2002 Minnesota and North Dakota crops were compared to pearling and other techniques for assessment of PHS. Approximately 30% of the seed evaluated were sprouted. Samples were evaluated for osmolyte concentrations, pearling, and Stirring Number, while smaller subsets were evaluated using other methodologies. Osmolyte concentrations correlated well with pearling (r=0.822, P<0.0001) and fluorescein dibutyrate staining (r=0.835, P<0.0001). Alpha-amylase activity correlated less positively with osmolyte concentration (r=0.650, P<0.0001). Stirring Number, Falling Number, germination, and accelerated aging correlated negatively with osmolyte concentration. It is concluded that seed osmolyte concentration, a quick and simple assay, is a good indicator of PHS in barley as assessed by the pearling method or fluorescein dibutyrate staining.