Cotton Genomics and Genetics 2025, Vol.16, No.2, 95-106 http://cropscipublisher.com/index.php/cgg 96 improve post-harvest management of cotton and provide a scientific basis for improving cotton quality and industrial benefits. 2 Factors Affecting Cotton Quality after Harvest 2.1 Harvesting time and method From field harvesting to processing, storage and transportation, the handling methods of each link will affect the final fiber quality. The selection of cotton harvesting time and picking method are directly related to the quality of seed cotton. Timely harvesting can prevent the fiber from being overly exposed to adverse weather and deteriorating. For example, if the cotton is picked at night or in the early morning when the dew is heavy, the moisture content of the seed cotton is high, fiber spots are prone to appear and the subsequent processing is more difficult (Van Der Sluijs and Delhom, 2017). On the contrary, harvesting when there is sufficient sunlight, the cotton bolls are fully opened and the cotton bolls are dry is conducive to keeping the fiber clean and strong. In addition, the difference in harvesting methods has a significant impact on cotton quality. Manual hand-picked cotton is picked one by one, with low impurity content and complete fiber, and high quality; while mechanical cotton picking harvests the entire cotton boll at one time, which inevitably carries cotton husks, leaves and other debris, and the impurity rate is usually higher than hand-picked cotton (Figure 1) (Kazama et al., 2015). The study by Zhang et al. (2021) showed that the content of foreign fibers and impurities in machine-picked cotton fibers increased significantly, which is one of the important factors affecting cotton quality. Therefore, while promoting mechanized harvesting, it is necessary to improve the front-end impurity removal technology to reduce the quality decline caused by the harvesting method. Figure 1 Classification of machine and hand picked cotton pollution a) 1-leaf, 2-stem, 3-funiculi, 4-seed coat, 5-shale, 6-grass, 7-steck; John Deere is a cotton picker b) (Adopted from Egamberdiev et al., 2024) 2.2 Field processing and transportation The field processing and transportation methods of cotton after harvesting will also affect the fiber quality. If the cotton seeds are not dried in time after harvesting and are bagged and stacked, the excessive moisture and temperature will easily cause the cotton pile to heat up and mold, causing the fiber color to turn yellow and the strength to decrease. For example, when the cotton seeds are soaked in water, the wax on the fiber surface is destroyed, the color is yellow-brown, and the humidity increases. Long-term stacking will breed mold and form moldy cotton (Birrer et al., 2021). In addition, if the mixing of field impurities is not effectively avoided after
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