Abstract
A low steely grain rate is important for obtaining a high quality hull-less barley. To determine the factors that are related to steely grain rate, we observed endosperm tissue structure and performed multi-regression analyses of the correlation of steely grain rate with several grain quality characters using grain samples of the hull-less barley cultivar “Mannenboshi.” Two sample groups from cultivation trials at Ehime Prefectural Research Institute of Agriculture in 2011 (21 samples) and 2012 (69 samples), and one group of samples from 21 farmers in the entire area of Ehime prefecture in 2011 were used in the experiment. In all of the three sample groups, the glassy grains were confirmed to have endosperm cells that were filled with matrix proteins around the starch granules. Based on the correlation analysis with steely grain rate, the grain-specific gravity showed significant correlations in all sample groups, and the grain protein content, known to be an influencing factor in formation of glassy grains, in all sample groups. Thus, the glassy grain rate was largely influenced both by the degree to which they filled the endosperm cells, as indicated by the grain-specific gravity and the amount of grain protein as the filler in the endosperm cells. Indeed, in all sample groups, the explanation ratios (R2) for the steely grain rate was larger in the two factor regression model that included both the grain protein content and the grain-specific gravity as compared with the single regression model of grain protein content.
