Changes in genetic diversity during seven cycles of recurrent selection for grain yield in oat, Avena sativa L.

Variability for desirable alleles within elite breeding populations is a requirement for long-term genetic improvement. Changes in genetic diversity were evaluated in a recurrent selection programme for enhanced grain yield in oat, AL ena sativa L., using coefficient of parentage (r(p)) and restriction fragment length polymorphism (RFLP) based genetic similarity (s) estimates. Both r(p) and s increased during seven cycles of recurrent selection, indicating a reduction in the level of genetic diversity within the population. The relationship between generic diversity and agronomic performance was also examined. Genetic similarity measures were poor predictors of the near-homozygous progeny performance and general and specific combining ability effects for three agronomic traits in the recurrent selection programme. in addition, there was no apparent trend for preferential selection of progeny from either more similar or more diverse parents within a given cycle of selection. The overall reduction in genetic diversity in this population has not affected selection response for grain yield. Variability remaining at important loci or de novo variation are possible explanations for the continued selection progress.