THE EFFECT OF A GENE FOR SEMIDWARFISM (Rht1) ON VARIOUS CHARACTERS IN A SPRING WHEAT CROSS

Sixty-four F2-derived F4 lines were produced from a cross between the semidwarf wheat (Triticum aestivum L.) cultivar CSP-44 (Condor sib, Rht1) and the tall cultivar Glenlea (rht1). Thirty-two homozygous tall lines and thirty-two homozygous short lines were tested at Saskatoon under rainfed conditions in 1982 and both rainfed and irrigated conditions in 1983. The objective was to determine the effects of the gene for demidwarfism on yield and other characters under Saskatchewan conditions. The semidwarf lines consistently had more spikes per metre of row and more kernels per spike, but a lower weight per kernel. The percent increase in the number of kernels per spike for the semidwarfs compared to the tails varied more in different environments than the change in the other two components of yield. As a result, the semidwarf lines outyielded the tall lines by 13.1% in the 1982 rainfed test and by 4.1% in the 1983 irrigated test but yielded 2.7% less in the 1983 rainfed test. In general, yield showed only low positive correlations with the yield components, while the yield components showed relatively low negative correlations among themselves.Key words: Wheat, Triticum aestivum, height, semidwarfs, yield components