Cotton Science 2005£¬17(2)£º99-102
Colorful Cotton Selection through Distant Hybridization and Semigamy Abstract: Small boll, low ginning outturn, short fiber, low special strength,in consistent color, serious segregation and unstable pigment heredity are common problems for colorful cotton and the routing crossing measures showed poor effect on improvement of quality performance. The application of wild cotton with insect resistance and potential fine fiber quality is of great significance to selection of new color cotton lines by playing full advantage of these fine quality traits and to overcome barriers caused by the long period shortage of hereditary basis and narrow variance potentiality. Some colorful cotton progeny of G. hirsutum with G.anomalum£¬G.sturtianum and G.raimondii have been obtained by hormone treatment and chromosome doubling, their quality performance have been remarkablely improved through crossing, back-crossing and polymerization by our team engaged in cotton distant hybridization since 1980.Unfortunately, those obtained progeny showed wild segregation. To stabilize these progeny, semi-gamogenesis material VSG was introduced in 1993 and has been employed as female parent in crossing with these colorful cotton distant hybridization progeny to get haploid, of three patterns of male parent, female parent and chimera ones. Chromosome doubling has been conducted for the produced male parent haploid and finally five new lines have been developed. Those five new lines are all progeny of chromosome-doubled homozygous diploid and their descendants are uniform. The quality test scores done by Chinese Center of Cotton Quality are: fiber length¡Ý29.0mm£¬special strength¡Ý26.4 cN¡¤tex-1£¬micron values in a range from 3.8 to 4.6, which greatly improve and stabilize their quality. The results suggest that the combination of distant hybridization and semigamy selection is effective to speed selection of color cotton with fine and stable integrated traits and the application of semigamy could stabilize those progeny of poor hereditary basis. Since haploid doubling is controlled by variety heritage and the environment and the successful rate is usually as low as 15%, the haploid doubling is the key technique for the application of VSG in breeding. And the low appearance frequency of haploid is another limiting factor for the application of VSG in breeding. Besides, there is performance difference between colorful cotton haploid sister lines. It needs further investigation to approach whether it was caused by the available genetic difference between sister lines.
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