Prediction Of Semidwarf Culm-Length Genotypes In Wheat

Two major independent genes, Sd and Sd, control semidwarf culm length in wheat (L.) and singly produce very similar culm-length phenotypes. Culm-length genotypes of semidwarf lines have normally been determined by evaluating culm-length distributions for F populations of test crosses to known Sd and Sd lines. In the present study, test crosses of eight semidwarf lines of unknown genotype were made to Sd and Sd tester lines to test the premise that the magnitudes of variance for coleoptile length and culm length varied directly with one another in F populations. The results verified that variance of coleoptile length closely corresponded with the variance of culm length in all F populations. The culm-length genotypes of the eight semidwarf lines were accurately predicted using the F coleoptile-length variance values. The coleoptile test is particularly valuable because measurements can be obtained in 8 days, and the test requires little space and much less labor than the F culm-length method. Identification of culm-length genotype is a necessary first step before the association of these specific genes with seedling vigor, winter survival, grain yield, quality criteria, and other important traits can be determined.