Multitrait response to selection in lolium perenne l. (perennial ryegrass) populations

Abstract

Genetic variation for growth, quality and persistency characteristics was assessed in six breeding populations of perennial ryegrass. Response to multitrait selection was predicted in each population using a selection index based on 10 traits. Predicted response was compared with that observed after one generation of half-sib family selection based on breeder’s preference. There was generally good agreement between predicted and observed response and it was possible to use predictions to identify populations with good potential to meet breeding objectives. For two of the breeding populations, observed selection responses after three generations of recurrent selection and in the progeny of survivors from cut and grazed plots were used to estimate selection pressures on individual traits. It appears that greater selection pressures are imposed on heading date and summer regrowth under grazing compared with cutting managements. The results illustrate the value of a multivariate approach in predicting the progress of breeding programmes and in identifying traits most affected by natural selection pressures. © 1995 The Genetical Society of Great Britain.