Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2005
Publication Date: 5/1/2006
Citation: Doehlert, D.C., Jannink, J., McMullen, M.S. 2006. Kernel size variation in naked oat. Crop Science. 46:1117-1123. Interpretive Summary: Naked oats are oats that thresh free of their hulls at harvest, in contract to hulled oats that retain a hull after harvest. Hulled oat spikelets may contain one to three kernels per spikelet, and kernel size is primarily controlled by the position of the kernel in the spikelet. The first or primary kernel is always the largest and kernel size decreases with increasing order of kernel. The naked oat spikelet has a distinctly different appearance and may contain as many as six kernels. Because of the profound difference in architecture, we inquired as to how this might affect the oat kernel size distributions. Our results indicated that naked oat kernel size is much smaller than hulled oat size, primarily because of their lack of a hull. There was much less difference in hulled groat sizes from naked groat sizes. Like hulled oats, the order of kernel within the spikelet was the most important factor affecting naked oat kernel size.
Technical Abstract: Oat kernel size uniformity is important to impact dehulling settings for optimal dehulling efficiency in commercial oat milling. Here we compare hulled oat size distributions with those of naked oats. Normal hulled oats have bimodal size distributions, which appears to be related to the architecture of the oat spikelet. Most oat spikelets have two kernels, where the primary kernel is distinctly larger than the secondary kernel. Naked oats have a distinctive multiflorous spikelet architecture. Our analyses indicated that spikelets from the ten naked oat genotypes contained from one to six kernels. Single kernel and double kernel spikelets were the most abundant. Analyses of size distributions indicated that all hulled oats and most naked genotypes had size distributions departing from normality, but many naked genotypes had normal size distributions. Also, the variances of naked oat size distributions were much smaller than those of hulled genotypes, indicating a greater degree of uniformity in naked genotypes. A test for bimodality indicated that many naked genotypes were less bimodal than the hulled lines. The results suggested that the multiflorous type naked oat spikelets may generate better uniformity for kernel size that the hulled oat spikelet.