Evaluation of Rapid Cycle Recurrent Selection for Early Flowering in Oat

More efficient methods of recurrent selection are important to oat (Avena sativa L.) breeding. Although recurrent selection methods have been utilized successfully for the improvement of a number of traits in oat, rapid-cycle population improvement methods for moderately to highly heritable traits have not been evaluated. Our objectives were (i) to evaluate effectiveness of rapid-cycle recurrent selection for early flowering, and (ii) to determine the effect of selection for early flowering on grain yield, maturity, and plant height. Phenotypic recurrent selection for early flowering was practiced for four cycles. The scheme requires one generation per cycle and up to three cycles can be completed in 1 yr. From each of the 30 selected plants in all four cycles, a single F₂:₄ line was derived for replicated testing. All derived lines and the original parents were evaluated at Rosemount and St. Paul, MN, in 1992 and 1993. Analysis of F₂:₄ lines from the earliest 12 plants per cycle indicated that selection reduced days-to-flowering by 1.25 days per cycle. Grain yield and plant height were reduced by 25 and 8%, respectively. Although the selection was effective, this population resulted in an unacceptably high frequency of aneuploid and phenotypically off-type progeny. Cytological analysis of the original F₁ hybrids indicated the presence of chromosomal interchanges between some of the Co parents. We hypothesize that the absence of a selfing generation in a closed recurrent selection system enhanced chromosomal interchange differences, resulting in a high frequency of off-types and aneuploids in later cycles. Therefore, if interchanges are present between breeding lines, recurrent selection without selling in oat may not be a useful method for long-term selection programs. Joint contribution of the Kansas Agric. Exp. Stn. and the Minnesota Agric. Exp. Stn. Contribution no. 94-517-J of the Kansas Agric. Exp. Stn. and journal series no. 21,517 of the Minnesota Agric. Exp. Stn. Research supported in part by the Quaker Oats Co.