Production of New Cotton Interspecific Hybrids with Enhanced Fiber Fineness

To improve cotton fiber fineness, the (Gossypium hirsutum L. × Gossypium longicalyx Hutch. & Lee) allohexaploid and the [(Gossypium hirsutum L. × Gossypium thurberi Tod.)² × G. longicalyx] allotetraploid were backcrossed to G. hirsutum to produce introgressed genetic stocks. The ribbon width (RW) of 600 swelled fibers produced by the hybrids, their parents, and their backcross progeny were analyzed for each compared genotype using an optical microscope. The RWs varied between 6.41±2.15 μm for G. longicalyx to 17.45±2.98 μm for the G. hirsutum parent cultivar C2. Fibers produced by the trispecific hybrids and their progeny were finer than the bispecific hybrid material. For the introgressed stocks, the lowest RWs were observed for the trispecific hybrid (10.79±2.14 μm) and certain backcross progenies (between 11.98±1.27 μm to 12.71±1.61 μm). The allohexaploid RW was 13.58±1.41 μm. One of its tetraploid progeny produced approximately the same value (13.94±2.48 μm). These results show that G. longicalyx is a potential genetic stock for cotton fiber fineness improvement. The genetic stocks produced are valuable materials for improve the fineness of cotton fiber.