Barley Seed Osmolyte Concentration as an Indicator of Preharvest Sprouting (1). Cynthia A. Henson (2), USDA-ARS Cereal Crops Research Unit, Madison, WI, and Department of Agronomy, University of Wisconsin, Madison, WI; Stanley H. Duke, Department of Agronomy, University of Wisconsin, Madison, WI; and Paul Schwarz and Rich Horsley, Department of Plant Sciences, North Dakota State University, Fargo, ND. (1) Mention of a proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other suitable products. (2) Corresponding author. USDA-ARS Cereal Crops Research Unit, 502 Walnut St., Madison, WI 53726. E-mail: <Cynthia.Henson@ars.usda.gov>; Phone +1.608.262.0377. J. Am. Soc. Brew. Chem. 65(3):125-128, 2007.

This study was conducted to test the hypothesis that barley seed osmolyte concentrations (OCs) can be used as an indicator of preharvest sprouting (PHS). Samples from the 2002 Minnesota and North Dakota crops were used. Seed samples ranged from approx. 70 to 100% in their ability to germinate. Samples were evaluated for OC, pearling, fluorescein dibutyrate staining, stirring number, falling number, and alpha-amylase activity. Pearling and fluorescein dibutyrate indicated samples ranged from 0 to approx. 25% sprouted. OCs 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 OC (r = 0.650, P < 0.0001). Stirring number and falling number had weak negative correlations with OC. We concluded that seed OC is a good indicator of PHS in barley as assessed by the pearling method and fluorescein dibutyrate staining. However, unlike the pearling method and fluorescein dibutyrate staining, OC values have the advantage of not being subject to visual interpretation and possible subjective bias. OC values are direct numerical measures of a physical property that changes dramatically during germination and are not simple positive or negative assessments. Keywords: alpha-Amylase, Barley, Fluorescein dibutyrate, Osmolyte concentration, Pearling, Preharvest sprouting

Este estudio fue conducido para probar la hipótesis que concentraciones de osmolito en semilla de cebada (OCs) se pueden utilizar como indicador de brote precosecha (PHS). Las muestras de las cosechas de 2002 de Minnesota y de North Dakota fueron utilizadas. Las muestras de semilla extendieron a partir de aproximadamente 70 a 100% en su capacidad de germinar. Las muestras fueron evaluadas para OC, “pearling,” tinte de fluoresceína dibutirato, índice de agitación, índice de caída, y actividad de alfa-amilasa. “Pearling” y fluoresceína dibutirato indicaron que las muestras se extendieron a partir de 0 a aproximadamente 25% brotadas. OCs correlacionó bien con “pearling” (r = 0.822, P < 0.0001) y tinte de fluoresceína dibutirato (r = 0.835, P < 0.0001). La actividad de alfa-amilasa correlacionó positivamente menos con OC (r = 0.650, P < 0.0001). El índice de agitación y índice de caída tenía correlaciones negativas débiles con OC. Fue concluido que la semilla OC es un buen indicador de PHS en cebada determinado por el método de “pearling” y tinte de fluoresceína dibutirato. Sin embargo, desemejante del metodo de “pearling” y tinte de fluoresceína dibutirato, los valores de OC tienen la ventaja de no ser conforme a la interpretación visual y al sesgo subjetivo posible. Los valores de OC son numéricas directas medidas de una característica física que cambie dramáticamente durante la germinación y no son observaciones positivas o negativas simples. Palabras claves: alfa-Amilasa, Brote precosecha, Cebada, Concentración de osmolito, Fluoresceína dibutirato, “Pearling”