The cytogenetics and fiber properties of an allohexaploid between Gossypium hirsutum and G-somalense

Cytogenetics and fiber properties were studied on the Gossypium hirsutumxG. somalense F-2 hybrid and later generations. The cytological analyses of po llen mother cells (PMCs) were made at meiotic metaphase I. The results indi cated that the hybrid was a new allohexaploid, its chromosome number determ ined as 2n=6x=78, and genome group as 2[(AD)(1)E-2]. Chromosomal configurat ions of the hexaploid averaged 0.15 I + 38.72II + 0.11III + 0.02IV per cell , 85.09% PMCs having 39 bivalents, and only 11.84% PMCs having I to 2 multi valents, indicating that heterogenetic recombinations of chromosomes occurs between (AD)(1) and E-2, nevertheless, the frequency is lower. The hexaplo ids are self-fertile and the progenies remain the hexaploids, whose fibers are light brown and have higher strength by measurement of HVI 900 system. The fiber strength increases 42% than that of upland cotton variety. Theref ore, it is possible for the hexaploid to be an important germplasm resource to improve fiber strength of cotton.