Cytomorphology of interspecific hybrids between Gossypium hirsutum L., its haploid and Gossypium raimondii

Interspecific hybrids between G. hirsutum, its haploid and G. raimondil were obtained. Morphological studies of different characters indicated that flower colour, petal spot, filament colour, pollen colour, stems, leaf hairiness etc. of G. raimondil were found to be dominant In both the hybrids while other growth characters and habit were intermediate. Meiosis in G. hirsutum and G. raimondil was normal leading to formation of viable pollen, however, in haploid and both the hybrids it was abnormal. On an average chromosome associations at diakinesis and metaphase-i were 4.11^I+ 4.69^II + 4.17^III and 5.30^I+ 4.20^I + 4.10^III and 10.55^II + 10.27¹¹ + 1.13^III + 1.13^IV and 10.29^I + 10.99^II + 1.39^III + 0.64^IV, in diploid (G. hirsutum haploid x G. raimondil) and triploid (G. hirsutum x G. raimondil), hybrids, receptively. Further, 4 to 6 bivalents observed in hybrid between G. hirsutum haploid x G. raimondil were due to pairing between. A_h D₅ chromosome of G. hirsutum and G. ralmondil, respectively and also A_h with D_h and D₅ chromosomes. In addition, bivalents formed in diploid hybrid and trivalent and quadrlvalents in triploid hybrid due to pairing between non-homologous chromosomes. Pattern of chromosome pairing indicated that chromosomes from D₅ genome of the G. raimondil have closer homology with A_h D_h. chromosomes of G. hirsutum. Formnation of multivalents, univalents and unequal separation of chromosome has resulted in formation of sporads containing 1–7 spores leading to formation of sterile pollens with high size variation.