Submitted to: Journal of Cotton Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/24/2007
Publication Date: 10/1/2007
Citation: Zeng, L., Meredith Jr, W.R., Boykin, D.L., Taliercio, E. 2007. Evaluation of an Exotic Germplasm Population Derived From Multiple Crosses Among Gossypium Tetraploid Species. Journal of Cotton Science. 11:118-127. Interpretive Summary: The US cotton industry greatly needs higher quality fiber to meet the requirements of modern high-speed textile equipment and the export of raw cotton. An evaluation was made of exotic germplasm derived from crosses between upland cotton and its wild relatives. Great genetic diversity was found in this germplasm for yield, fiber strength, fiber length, and other properties that are important for spinning of fibers into yarn. Some lines in this germplasm were desirable for both yield and fiber quality. Morphological characters useful for insect resistance and crop management were also identified in the germplasm. The lines identified with desirable genes will help breeders to continuously improve both cotton yield and fiber quality. This germplasm will be released to the public after appropriate yield testing.
Technical Abstract: Broadening the genetic base of upland cotton (Gossypium hirsutum L.) is essential for continuous genetic improvement of yield and fiber quality through breeding. A population was developed by crossing cultivars and strains of G. hirsutum with the other tetraploid species in the genus. This population, designated as the Species Polycross (SP), underwent 11 years of random mating by natural pollination in an isolated environment with high bee activity followed by 12 years of selfing. The objectives of this experiment were to evaluate the SP population for phenotypic and genotypic variations in yield and fiber quality, investigate morphological variations among the SP lines, and analyze the interrelationships among yield, yield components, and fiber properties. The experiment was conducted at two locations with two replicates each. Two hundred and sixty lines of SP population were evaluated with five commercial cultivars. Genotypic variation was significant (P<0.01) for all characters of yield and fiber quality. Although highly significant (p<0.01) interaction between genotype and location was identified for fiber strength and most yield parameters, the interaction components were small relative to the genotypic components. The results suggest the emphasis of general adaptability in breeding when the SP population was used as a germplasm resource. There were wide ranges of means among the SP lines for yield components and fiber properties. There was large variation among SP lines for nectary size, gland content in leaves, pubescence, leaf cut depth, plant height, leaf area, leaf length, and node number of the first fruiting branch. The results provide evidence that the SP population is a useful germplasm resource for genetic improvement of lint yield and fiber quality. Lint percentage was negatively correlated with fiber strength and span length. Lint percentage in SP population was significantly (P<0.01) lower while boll weight and seed weight were significantly (P<0.05) higher than the average of the cultivars. Span length (50%) contributed more variation to fiber strength than span length (2.5%), in the SP population. Lint yield was negatively correlated with short fiber content.