EFFECTS OF SELECTION AND OPPORTUNITIES FOR RECOMBINATION IN DOUBLED-HAPLOID POPULATIONS OF BARLEY (HORDEUM-VULGARE L)

Doubled-haploid breeding systems are typically based on sampling gametes from F-1 plants. However, in the case of repulsion linkages, additional recombination could be advantageous. Pre-selection of gamete donors might also shift progeny performance in a desired direction. The objectives of this study were to quantify the effects of an additional round of recombination and assess the effectiveness of preanthesis selection in the production of barley doubled haploids. Assessments were conducted on: 1. 100 F-1-derived lines representing a subset of lines used in previous genome-mapping studies; 2. 100 random F-2-derived lines; and 3. 50 F-2-derived lines from gamete donors selected for early heading. An additional round of recombination had only a modest effect on generating more favourable genotypes. Pre-anthesis selection was ineffective in generating an earlier heading population. According to published quantitative-trait locus (QTL) analyses based on the F-1-derived population, there are few repulsion linkages between QTL determining the traits measured in this experiment. Any advantages to be gained from postponing the generation of derivation of doubled haploids must be weighed against the delay and additional cost.