Size Distributions of Different Orders of Kernels within the Oat Spikelet

Oat kernel size uniformity is of interest to the oat milling industry because kernel size is important in the dehulling process. Previous studies indicated that oat kernel size distributions are bimodal. In this study oat spikelets were dissected into primary, secondary, and tertiary kernels and kernel size distributions were determined for each of these kernel orders by digital image analysis. Spikelets with two kernels are the most abundant, and their primary and secondary kernels have distinctly different size distributions. These two kernel spikelets appear to be responsible for the bimodal distribution observed among oat kernels. Primary kernels from single kernel spikelets and primary, secondary, and tertiary kernels from triple kernel spikelets all had different mean sizes and distributions. These kernels appeared to contribute to deviations from bimodal distributions. Thus, data presented provide direct definitive evidence that the non‐Gaussian distributions observed for oat kernel sizes are derived from the combination of subpopulations from each of the different orders of kernels from within the spikelet. Sieving analysis of kernel types indicated that for the samples analyzed here, secondary kernels from two kernel spikelets and tertiary kernels from three kernel spikelets appear to contribute equally to undersized kernels under 2 mm in width. Thus, from a kernel size prospective, no advantage can be attributed to the elimination of three kernel spikelets by selective breeding.