Methods to determine dormancy and preharvest sprouting resistance in Barley
Preharvest sprouting (PHS), defined as germination of seeds on plants before harvest, is an ever-present problem and concern for barley (Hordeum vulgare L.) growers, processors, and researchers worldwide. A major factor leading to PHS is a lack of seed dormancy, the failure of viable seeds to germinate under favorable conditions. The objectives of this research were to identify a simple, quick, and consistent method to determine the dormancy level and PHS resistance using 14 barley genotypes. The genotypes were grown in two greenhouse trials and six field experiments in North Dakota in 2004, 2005, and 2006. Two methods to determine dormancy and one method to determine PHS resistance were evaluated. Spikes harvested at harvest maturity were used for the germination test and artificial rain treatment to determine the dormancy level, whereas stirring number was measured on seeds from spikes that underwent field weathering to determine PHS resistance. All three methods evaluated had repeatability values ≥0.89. In addition, the 'moderately strong' correlations (r = 0.73–0.88) between the three methods suggested that any of the methods could be used to determine the dormancy level and/or PHS resistance of barley genotypes. However, the germination test was preferred because it is simple and fast and does not require expensive equipment. Testing using greenhouse-grown materials can be used to screen for nondormant genotypes that may undergo PHS in the field and therefore must not be released as cultivars.