Did Recurrent Selection for Yield Affect Iowa Stiff Stalk Synthetic Maize Population Grain Fill Characteristics?.

Hybrid maize yield increases, new product development, and increased stress tolerance can be more easily achieved with a better understanding of the physiological and genetic basis for phenotypic changes in response to recurrent selection.  Yield increases of modern day maize hybrids might be partially attributed to a change in grain fill characteristics.  The purpose of this study was to identify grain fill characteristics and their interaction with plant density in selected and unselected Iowa Stiff Stalk Synthetic Populations.  Plots were planted at 53,000 and 77,000 seeds per hectare.  Two ears from each treatment were harvested at weekly intervals beginning 15 days after silking. Ten kernels from spikelet positions 10-15 were removed and dried at 70° C until kernel weight remained constant.  A non-linear mixed model was fitted to the data, and both cycle of selection and planting density affected grain fill characteristics.