A Study of the Cytological Observations on Thirteen Different Monosmic F\u3csub\u3e1\u3c/sub\u3e Hybrids from Crosses between Two Wheat Varieties

Thirteen different monosomic F1 hybrids between Chinese Spring monosomics and the hard red winter wheat variety Cheyenne, were observed at metaphase I of meiosis with respect to frequencies of extra univalent and lengths of Cheyenne chromosomes. The average number of extra univalent per cell varied from .235 for chromosome 5D (XVIII) to .770 for chromosome 3B (III), with significant differences among different monosomics. A range of from two to six extra univalent per cell was observed. The variation in extra univalent frequency was contributed primarily by the chromosome-to-chromosome variance. The 13 chromosomes of Cheyenne were classified statistically into three distinct groups according to their lengths. The lengths varied from 4.23 microns for chromosome 6D (XIX) to 7.22 microns for chromosome 3B (III). The coefficients of variation ranged from 5.73 percent for chromosome 6A (VI) to 10.09 percent for chromosome 2A (II). The variation in length of specific chromosomes was attributed to the variances due to florets, heads (including sampling dates) and different chromosomes. Advisor: Rosalind Morris