Cytogenetic distinctiveness of sixty-six tetraploid cotton (Gossypium hirsutum L.) cultivars based on meiotic data

Acytogenetic study was performed on 66 tetraploid cotton cultivars (Gossypium hirsutum L.) and their hybrids. The cultivars studied differed significantly in their chiasma frequency and distribution as well as chromosome pairing indicating their genetic differences. Adjacent and alternate quadrivalents were formed in most of the cultivars. A-A or D-D heterozygote translocations occurred in most of the cultivars, while A-D (V-type) heterozygote translocations occurred in the cultivars Sahel, Oltan X Sahel and Modified. The cultivars B557, Modified, Sahel and Tashkand showed the occurrence of chromosome migration and aneuploid meiocytes. B-chromosomes occurred in some of the cultivars. Clustering of the cultivars showed distinctness of some of the parental genotypes and their hybrids. The Cytogenetic differences observed if combined with morpho-agronomic characters may be used in cotton breeding.