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

摘要

Interspecific hybrids between G. hirsutum, its haploid and G. raimondii were obtained. Morphological studies of different characters indicated that flower colour, petal spot, filament colour, pollen colour, stems, leaf hairiness etc. of G. raimondii were found to be dominant in both the hybrids while other growth characters and habit were intermediate. Meiosis in G. hirsutum and G. raimondii was normal leading to formation of viable pollen, however, in haploid and both the hybrids it was abnormal. Onan average chromosome associations at diakinesis and metaphase-l were 4.11~I + 4.69~(II) + 4.17~(III) and 5.30~I + 4.20~(II) + 4.10~(III) and 10.55~(II) + 10.27~(II) + 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. raimondii} and triploid (G. hirsutum x G. raimondii), hybrids, receptively. Further, 4 to 6 bivalents observed in hybrid between G. hirsutum haploid x G. raimondii were due to pairing between. A_h D_5 chromosome of G. hirsutum and G. raimondii, respectively and also Ah with D_h and D_5 chromosomes. In addition, bivalents formed in diploid hybrid and trivalent and quadrivalents in triploid hybrid due to pairing between non-homologous chromosomes. Pattern of chromosome pairing indicated that chromosomes from D_5 genome of the G, raimondii 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.