CONTINUED RESPONSE THROUGH 7 CYCLES OF RECURRENT SELECTION FOR GRAIN-YIELD IN OAT (AVENA-SATIVA L.)

Long-term selection experiments provide germplasm to study the effects of selection in a closed population. Recurrent selection to enhance g rain yield in oat has been ongoing at the University of Minnesota sinc e 1968. The objectives of this study were: (i) estimate the GCA and SC A effects for three agronomic traits in the seventh cycle of selection , (ii) assess the effect of the current methods of selection on parent al contribution and unselected traits, and (iii) determine the direct and indirect responses to seven cycles of recurrent selection for grai n yield. Progeny of the Cycle 6 parents and parents for Cycles 0 throu gh 7 were grown in two separate tests. Grain yield, heading date and p lant height were evaluated in each test. Grain yield was increased by 21.7% after seven cycles of selection. Evaluation of Cycle 6 progeny s howed that GCA effects were significant for all three traits studied, and SCA effects were significant only for grain yield. Four Cycle 6 pa rents did not have any progeny selected as Cycle 7 parents. Results fr om this study indicate that long term recurrent selection has continue d to increase grain yield. Alternative selection strategies may be nec essary to maintain the genetic variability in this population, particu larly when improvement of secondary traits is required.