Cotton fiber properties are essential predictors of yarn performance. The suite of fiber quality traits that collectively affect the utility of the fiber for the textile industry include the length, the strength, the fineness and the color. These properties have been shown to be moderately to highly heritable. In an attempt to overcome the limitations of conventional breeding we undertook a marker‐assisted selection program aimed at introgressing fiber quality QTLs from Gossypium barbadense L. into G. hirsutum L. We describe the QTL analysis of 11 fiber properties measured on three phenotypic data sets. The three populations studied were the 1st (BC1) and 2nd (BC2 and BC2S1) backcross generations derived from the cross between ‘Guazuncho 2’, G. hirsutum, and ‘VH8’, G. barbadense Collectively we detected 80 QTLs, of which 50 surpassed the permutation‐based LOD thresholds (3.2–5.7). The most economically important traits, length (two correlated properties), strength, fineness (four properties), and color (two properties) were influenced by 15, 12, 21, and 16 QTLs, respectively, that could be detected in one or more populations. As expected, for the majority of QTLs, the favorable alleles came from the G. barbadense parent. Altogether one third (26) of the QTLs confirmed the map position and phenotypic effect of QTLs reported in the literature also detected in interspecific G. hirsutum × G. barbadense populations. Cases of colocalization of QTLs for different traits were more frequent than isolated positioning. Taking these QTL‐rich chromosomal regions into consideration, 19 regions on 15 different chromosomes, were identified as target regions for the marker‐assisted introgression strategy.

An earlier study confirmed the influence of cotton fiber length characteristics on the High Volume Instrument™ (HVI) strength measurement and devised a quantitative correction factor to compensate for the effect. The current paper investigated the validity of two important assumptions utilized in the previous study. Firstly, single fiber testing confirmed that the particular sample preparation method used to generate samples of different fiber length characteristics from a common cotton sliver did not introduce any inherent damage to the fibers (and so this could not be the explanation for the observed trend in measured fiber strength as a function of fiber length). Secondly, the positioning of the jaws relative to the beard in the HVI strength measurement was explored. This positioning was found to be quite variable for replicate measurements on the same cotton being a function of the size of each individual beard. The average positioning between the different samples was found to be similar and this validated the assumption and approach used previously for deriving the correction factor for that particular sample set. Characterizing the position of the jaws was extended using a wider range of cotton samples. The HVI positioning algorithm appears to not simply be a function of the size of the beard (i.e. the ‘amount’ parameter), but is also dependent on fiber length characteristics. It was also observed that the reported HVI elongation values displayed both a significant bias due to fiber length and also a dependence on the size of individual beards tested.

Around 50% of the cotton bales produced in the world are sold based on the analysis of their technological characteristics using a standardized instrument for testing cotton (SITC). In the United States of America, periodical studies of variability of the results allow the results to be accompanied by commercial tolerances to limit the frequency of claims. However, to our knowledge, no such study has been conducted in Africa. For this reason, we studied within-bale variability of fiber micronaire, length, uniformity, strength, reflectance and yellowness as measured by the SITC. We took eight samples per bale from 215 cotton bales produced by 27 ginning mills in eight Sub-Saharan countries in Africa in two cropping seasons. Our representative sample was composed of 1720 fiber samples that were analyzed in controlled conditions using the SITC in a laboratory in which international recommendations are fully respected. We measured within-bale variability and suggest a sampling method and procedure to perform technological and instrumental tests in West and Central Africa.

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