| Oat (Avena sativa L.) panicles are divided into spikelets, which have a somewhat variable number of kernels. Commonly there are only two kernels, but three and even four can be present. In most cases the primary kernel is bigger than the secondary one, and both are bigger than the tertiary kernel (TK). Not much attention was given to TKs until a few years ago. Some plant breeders believe that a high TK frequency might have been indirectly selected when selecting for high grain yield and/or high test weight (TW). These TKs may contribute to higher yields (more sinks) and may allow better packing of seeds inside the TW cup, giving higher TW results. The latter becomes a problem as the industry needs uniform sized grain for more efficient milling. It is unknown how the presence of TKs influences the oat plant development and the size and shape of the other oat kernels. Sister lines were used to compare agronomic and physical characteristics of oat lines with high and low TK frequencies. The best way to evaluate TK frequencies was determined to be by counting the number of TK/spikelets in the middle third of panicles. There is significant GxE interaction, causing results to vary across environments. Grain yield, TW, groat % and hull retention were higher for the high TK lines. For the physical evaluations a detailed digital image analysis (DIA) experiment was conducted. Oat kernels vary for size and shape across kernel type, position in the panicle and presence or absence of TK in the spikelet. In most cases the kernels were smaller and more round when TK frequency was higher. Complementary studies using molecular markers for TK locus identification were conducted using the Kanota/Ogle population. The same 2 QTLs identified in a previous study were validated across three environments. |
