Origin and implication of seed coat fragment contamination on yarn quality

More than one third of the cotton grown worldwide is contaminated with SCF to some degree. There are at least two possible sources of SCFs that may contribute to the SCF contamination: broken seeds prior to ginning and during ginning. The varietal effect on the amount of SCF suggests designing breeding programs focusing on developing cotton cultivars with less propensity to produce SCF. In each stage of the breeding programs, the number of SCF needs to be measured to identify plants or lines with the potential to produce lint with less SCF, especially in the yarn. For this purpose, a rapid and valid SCF measurement method is required to be able to properly predict the level of contamination in the yarn. Trashcam, an image analysis tool, can count and size imperfections created by SCF and other trash materials in yarn and card webs. In the current study, several parameters were set in the Trashcam to successfully identify and count SCF in a large set of yarn samples. These parameters were validated by comparing the number of SCF found by the Trashcam with the human counts. Moreover, the result indicates that possibly the only way to predict SCF in the yarn is to use the Trashcam or a similar tool based on image analysis of yarns and card webs. The varieties studied in this project differ significantly for the number of SCF suggesting that the Trashcam could be used in breeding programs. Seed cotton is stored in the form of modules after harvesting and is transported to the gin. In the module building method, the seed cotton is compressed to give it the desired shape. However, the method has the potential to break or damage seeds when the compression force is applied. This could be a source of SCFs in the lint and thereby in the yarn. In the current study, we measured the seed coat compression force of fuzzy seeds by applying a compression force that mimics the module building method. Significant differences for the average force required to break the seed coats among the varieties suggest a possible genetic component for the amount of force a seed can withstand before breaking. Therefore, this method could potentially be used in breeding programs to avoid releasing lines or cultivars with fragile seed coats. An insignificant relationship was observed between Trashcam SCF count and compression force for this set of samples. This is not surprising as the samples selected for this study did not come from commercial modules. Moreover, Trashcam SCF count does not relate well to the AFIS SCN measurement indicating that the Trashcam on yarn boards better estimates the level of impurities in the yarn than the AFIS, i.e., the AFIS was done on raw lint. Therefore, Trashcam could be a better instrument in predicting SCF contamination in yarn. Trashcam SCF counts show poor relationship with fiber and yarn quality parameters. In addition, the insignificant relationships between Trashcam SCF and yarn evenness parameters suggest that SCFs are not responsible for most of the yarn defects as measured with the UT 5 for this set sample. Many SCFs are too small to be detected by the capacitive sensor of the UT 5. Nevertheless, they are clearly visible to the human eye.

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