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Submitted to: Crop Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/12/2005 Publication Date: 7/5/2006 Citation: Ulloa, M. 2006. Heritability and correlations of agronomic and fiber traits in an okra-leaf upland cotton population. Crop Science. 46:1508-1514. Interpretive Summary: Cotton is produced as a raw material for the textile industry and is a high value crop. Marketing of this crop is based on measurable quality properties in an industry where technology changes are being implemented rapidly. Modern cotton cultivars are good-yielding, day-length neutral flowering, early-cropping plants, and with abundant fiber. These improved characteristics resulted from human selection from perennial ancestors with shorter, sparser fiber. Much of the fiber trait variability exhibited by cotton at the textile mill has genetic origins. The continuing demands for better quality traits for consumer goods has been driving research programs to look for more alternatives to genetically improve lint and fiber quality. Plant breeding methods are chosen based on the ability to predict the effects of alternative procedures on rate of progress and potential improvement of a specific trait. The objectives of this study were to asses heritability and correlation trait estimates on single plant and progeny row performance over four generations. The trait heritability estimates and correlations may be useful in developing selection criteria to simultaneously improve yield and fiber quality traits. Technical Abstract: In cotton (Gossypium hirsutum L.), the cost and time to develop and evaluate appropriate genetic populations have limited the number of intensive and complete heritability studies. Herein, three agronomic and 17 fiber quality traits were assessed for heritability and correlation analyses on progeny rows in an okra-leaf cotton population of 208 families. Progenies were advanced in succeeding generations by a single-seed descent. Comparison between F2:3 and F2:6 generations for individual traits and individual progeny by trait revealed significant differences between the two generations. Heritability estimates (h2 > 0.60), and correlations within and between (r > 0.55) F2:3 and F2:6, generations have practical applications for the simultaneous improvement of multiple fiber traits. Fiber strength was positively correlated to 2.5 % and 50% fiber span length, and negatively correlated to short fiber content. Number of neps was positively correlated to number of seed coats, and short and immature fiber content, and negatively correlated to mean fiber fineness and maturity ratio. The genetic potential for improving agronomic and fiber traits may exist in populations with this alternative leaf morphology, okra-leaf type. Mass selection may be effective for improving most of the above traits (h2 > 0.60). However, pedigree, sibs, and progeny tests need to be used to achieve higher genetic progress. Selection may be applied as early as the F3 when selection units can be replicated. Thereafter, antagonistic trait correlations may become neutral or favorable in later generations, facilitating improvement of fiber quality. |
