EFFECTS OF RECURRENT SELECTION FOR GRAIN-YIELD ON OAT KERNEL MORPHOLOGY

Kernel size, as it is related to kernel weight, is an important yield component in oat (Avena sativa L.). The main objective of our research was to evaluate the changes in kernel morphology following five cycles of recurrent selection for grain yield. Parents of Cycles 0, 1, 3, and 5 and seven check cultivars were grown in row and hill plots at St. Paul and Rosemount, MN, in 1989. Kernel area, perimeter, length, and width were measured on 100-kernel samples from each plot using digital image analysis (DIA). Grain yield, kernel weight, and kernel number were also evaluated in these experiments. Grain yield was enhanced by 26.8 and 55.3% following five cycles of recurrent selection as measured in row and hill plots, respectively. Kernel area increased by 9.8 and 10.1% in row and hill plot samples, respectively. Kernel perimeter, length, and width increased by 4.8, 5.7, and 4.6%, respectively, in row plot samples. In hill plot samples, kernel perimeter, length, and width increased by 5.5, 6.8, and 3.7%, respectively. There were no significant difference among cycles for two derived shape factors, FCIRCLE (4 pi [kernel area]/[kernel perimeter]2) and kernel width/length ratio. Values for kernel area, perimeter, length, and width from hill plot samples were significantly larger than those from row plots; however, selection responses in the two plot types were quite similar. In this study, environmental influences on kernel morphology were minor. Kernel weight was positively correlated with the two size measurements, kernel area and width. Results from our study indirectly suggest that increased kernel size, and not kernel density, largely accounts for the observed increases in kernel weight. These experiments also demonstrate the utility of DIA in agronomic research.