SOME OBSERVATIONS ON POLYEMBRYONY IN CROSSES BETWEEN TWINNING AND NONTWINNING LINES OF FLAX

A recurrent selection program was initiated using the polyembryony character found in flax (Linum usitatissimum L.) to produce haploids that could then be used to create doubled haploid lines. Observations from this programme show that using the haploid member of a twin seedling as the female parent in crosses to the diploid male is not as efficient as using its diploid twin as the female parent. Previous work has suggested that in lines carrying the polyembryony character, bolls containing fewer than 10 seeds, which is the maximum number in flax, were more likely to contain a seed that would give rise to a twin seedling. In this study twin seedlings were obtained from seed of bolls containing from 1 to 10 seeds, and bolls with 10 seeds were often as good a source of twin seedlings as those with nine seeds or fewer. There was no significant difference in the twinning frequency of F2 seed of crosses between twinning and nontwinning lines (range 0.8–1.9%) but these same crosses were significantly different in twinning frequency in doubled haploid lines (range 1.1–7.9%). The twinning frequency of individual doubled haploid lines within crosses varied from 0.4 to 20.3%.Key words: Flax, haploid breeding, polyembryony, Linum usitatissimum