COMPARISON OF RELATED WHEAT STOCKS POSSESSING 1B OR 1RS.1BL CHROMOSOMES - AGRONOMIC PERFORMANCE

The 1RS.1BL translocation is widely used by wheat (Triticum aestivum L.) breeders to enhance agronomic performance and particularly grain yield. Research is lacking that compares agronomic trait expression in closely related stocks with or without the translocated chromosome arm. Our objective was to determine the effects of 1RS.1BL on means and genetic variances for grain yield and other agronomic traits in two hard red winter wheat populations segregating for the 'Aurora' translocation. Two field experiments were conducted using different genetic materials derived from two crosses, OK83398 x 'Chisholm' and OK83398 x 'Arkan'. In Experiment 1, 25 pairs of F-5-derived near-isolines homozygous for either 1B or 1RS.1BL were evaluated in three environments. In Experiment 2, plants homozygous for either 1B or 1RS.1BL were selected in the F-2, and further subsampled in the F-3; forty F-3(F-2) lines per chromosome type in each cross were evaluated in four environments. The average effect of 1RS.1BL in Experiment 1 was to increase grain yield by 9 to 10%, increase aerial biomass by 11 to 12%, and increase kernel weight by 4 to 6%, depending on the cross. Differences in kernels per spike, harvest index, and test weight were not detected, whereas differences in plant height and the number of spikes per meter squared were inconsistent between crosses or among environments. The magnitude of the effect of 1RS.1BL varied considerably among the paired near-isolines, presumably by the effects of genes present on other wheat chromosomes. Heterogeneity of genetic variance in Experiment 2 was usually caused by larger variance among 1RS.1BL genotypes than 1B genotypes. These results encourage further use of 1RS.1BL to improve agronomic traits of wheat.