EFFECT OF A 1R(1D) CHROMOSOME SUBSTITUTION ON 2 SPRING WHEAT CULTIVARS

The effect of a 1R(1D) chromosomal substitution on the spring wheat (T riticum aestivum L.) cultivars Wheaton and Marshall was studied to det ermine if the yield advantage, found in preliminary trials with 'Anza' in California, would be expressed in different environments and genet ic backgrounds. Three experiments were conducted at two locations in M innesota, from 1989 through 1991, with populations with and without th e rye chromosome substitution developed in each cultivar background: ( i) F-2 derived F-6 bulks; (ii) F-4 derived F-6 random lines; and (iii) paired F-6 lines derived from the same F-3 plant. Although, frequentl y, test weight was the only trait significantly reduced by the presenc e of the substitution, the 1R(1D) bulks and lines also tended to have lower grain yield protein content. In Experiments 2 and 3, the 1R(1D) lines tended to have shorter vegetative cycle and tailer plants. Kerne l weight was rarely affected by the substitution, but when there was a n effect, it was increased. Considerable genetic variability among bul ks and lines within the 1R(1D) and normal wheat groups in all the popu lations was observed. This allowed the identification of 1R(1D) lines that were similar to the parental check cultivars for grain yield. The random lines detected effects of the rye chromosome substitution with most resolution, probably because the lines were more homogeneous tha t the bulks and more random lines were tested than paired lines.