Nine cycles of recurrent selection for increased groat-oil content in oat

Increases in the great (caryopsis)-oil content of oat (Avena sativa L.) raise the energy value of oat grain. Nine cycles of recurrent phenotypic selection for high great-oil content were conducted in a genetically broad-based oat population that included germplasm from the wild relative A. sterilis L. Our objectives in this experiment were to determine if selection for high great-oil content was effective and if selection reduced genetic variation for oil content; to identify agronomically acceptable lines with high great-oil content; and to document the indirect effects of selection on grain yield, great fraction, and oil yield. We evaluated 100 random lines from the base (C0) population and each of the nine selection cycle populations in three environments. Mean great-oil content increased linearly during nine cycles of selection at a rate of 6.6 g kg(-1) cycle(-1) (equivalent to 6.7% of C0 population mean cycle(-1)) from a mean of 98.2 g kg(-1) in C0 to 158.5 g kg(-1) in C9. The rate of gain from selection did not decrease in later cycles, Oil yield increased at a rate equivalent to 1.9% of C0 population mean cycle(-1), while mean great fraction did not change and mean grain yield decreased at a rate equivalent to 3.2% of C0 population mean cycle(-1). For all traits, genetic variation did not decrease during selection cycles. Selected So-derived lines from the population with great-oil contents >150 g kg(-1) exhibited lon er yield, greater lodging, and greater disease susceptibility compared with the best check cultivar.