Evidence that minor sprout damage can lead to significant reductions in gluten strength of winter wheats

Seventeen winter wheat lines were grown in triplicate plots at Warsaw, Painter, and Blacksburg, VA, during the 1999-2000 growing season. Hagberg falling numbers, protein content, farinograms, sedimentation volumes, and total glutenin content were determined for flours derived from 153 harvested wheat samples. Over three inches (8.2 cm) of rain fell during the week before harvest in Blacksburg, resulting in falling numbers of 100 for Recital and 137 for Heyne, two severely sprouted Blacksburg wheat samples, and falling numbers < 250 in three other Blacksburg wheats. There were no significant differences across locations in falling numbers of four wheat lines, and one line had significantly greater falling numbers in Blacksburg than in Warsaw or Painter. All IS Blacksburg flours had a significantly higher mixing tolerance index (MTI) and shorter departure times (DT) than corresponding Warsaw flours. Weaker gluten strength of Blacksburg flours suggests that all 18 Blacksburg wheats were sprout-damaged and contained active proteases. However, according to falling number data, five of these Blacksburg wheats were sprout-free with falling numbers > 400. These data indicate that Hagberg falling number should not be used as the sole criteria for determining the degree of sprout damage in wheat because it does not quantify, nor always accurately reflect changes in protein composition and quality due to grain weathering.