Genetic analysis of a two-row x six-row cross of barley using doubled-haploid lines

A study was conducted on a two-row/six-row cross of barley to (1) determine the yield potential, (2) detect epistasis and genetic correlations, (3) estimate the heritabilities of six agronomic traits, and (4) study the effect of the V locus on the agronomic traits in the barley cross. The effects of five other marker loci (Re2, s, R, Est1, and Est5) on the six agronomic traits were also studied. One hundred and ninety doubled-haploid (DH) lines were derived from a Leger'/CI9831 cross using the bulbosum method. The DH lines and the two parents were tested for grain yield, test weight, seed weight, plant height, lodging, and heading/maturity at two locations in Eastern Canada in 1993. Additive x additive epistasis and genetic correlations were detected for some of the agronomic traits. Many of the heritability estimates were high; however, significant progress in yield improvement would be difficult to achieve because of a low mean yield of the DH lines. Under the growing conditions in Eastern Canada, six-row lines outyielded two-row by 20-27%. Six-row lines, however, were associated with low test weight, low seed weight, and severe lodging. Some two-row lines yielded higher than the two-row parent CI9831, but none of the six-row lines yielded higher than the six-row parent 'Leger'. The R, s, and Est5 loci were associated with the six agronomic traits, but the Est1 locus was apparently not associated with the agronomic traits. The effect of the Re2 locus was probably due to its close linkage with the V locus. Further studies are needed to determine if superior six-row lines can be developed from two-row/six-row crosses.