Development of a small scale method to determine volume and density of individual barley kernels, and the relationship between grain density and endosperm hardness

This study reports the measurement of grain density and grain volume of barley grains using a gas displacement technique. The densities of single kernels were determined and were highly correlated with measurements of larger quantities of kernels (10, 25 or 800). Grain weight and volume were significantly correlated when measuring 800 kernels (0.99, P < 0.001), 25 kernels (0.99, P < 0.001), 10 kernels (0.98, P < 0.001), and a single kernel (0.97, P < 0.001), and the standard deviations were low for the five replicate measurements.The relationship between grain density and endosperm hardness was significantly correlated (0.57, P < 0.001), as was the relationship between grain density and test weight (0.70, P < 0.001). Grain density was negatively correlated to moisture content (−0.65, P < 0.001), but not protein content. Endosperm hardness was positively correlated to protein content (0.45, P < 0.001), but not moisture content. Although grain density and endosperm hardness are interdependent physico-chemical traits, different grain components appear to interact independently. Gas displacement technique could be applied to determine the distribution of grain density within a sample. Therefore, this technique will assist breeding programs to identify genomic regions associated with these physico-chemical traits, and produce superior malting and feed quality through uniform varieties with inherently denser, plumper grain.

► Grain density and volume were measured on single barley grain using gas displacement.
► Grain density and endosperm hardness are interdependent physico-chemical traits.
► Density was negatively correlated to moisture content, but not protein content.
► Hardness was positively correlated to protein content, but not moisture content.
► Measuring density can assist genetic selection for malting and feed quality traits.