YIELD STABILITY OF DOUBLE HAPLOID LINES OF BARLEY

The effect of complete homozygosity and homogeneity on stability of grain yield in barley was studied in 38 doubled haploid lines derived from F1 plants of six biparental crosses. The number of doubled haploid lines in each cross ranged from 3 to 12. These along with 13 check cultivars were evaluated at five locations in Ontario in 1975 and 1976. The linear regression method proposed by Eberhart and Russell in 1966 was used to analyze the stability of grain yield. In general, the response of doubled haploid lines to different environments, based upon the regression coefficient, did not differ from the response of the check cultivars. Similar responses were also observed among check cultivars, among crosses, and among doubled haploid lines within crosses. Furthermore, the pooled deviation from regression mean squares for the check cultivars was not different from that for the doubled haploid lines. The mean yield of the doubled haploid lines was as high as that of the check cultivars. Significant differences in mean yield among crosses was not detectable but considerable genetic variability in grain yield was found among lines within three of the crosses. It appears that under Ontario conditions homogeneous and homozygous lines derived by the doubled haploid method are as good agronomically and have yields as stable as the licensed cultivars developed by conventional breeding methods.