Prioritizing fiber elongation over strength: key to work-to-break and length distribution

Improving fiber quality is crucial to preserve and gain market opportunities for Upland cotton. Although there have been considerable improvements in fiber length and strength, the global product offerings have not been notably impacted. Cotton competes with synthetic and manufactured fibers, which are stronger, have higher elongation, can be any length, and are highly uniform. The breeding community should focus on properties such as length uniformity; however, a potentially more vital attribute, fiber elongation, has previously been shown to be an essential part of the ability of fibers to survive mechanical stress, which might lead to better fiber length distributions. Different varieties from different seed companies were planted over three growing seasons with varying irrigation levels and then subjected to four different ginning treatments consisting of different levels and types of mechanical stress. The combination of different varieties, irrigation, weather, and ginning was designed to create a dataset of diverse fiber quality, specifically targeting a wide range of tensile properties. The data reveals significant behavioral differences from different forms of mechanical stress, especially with roller ginning. While roller ginning results in improved fiber length and uniformity, it is observed that this advantage is primarily associated with longer fibers. However, High Volume Instrument (HVI) elongation was lower with roller ginning, and the Advanced Fiber Information System (AFIS) length distributions revealed a higher proportion of undesirable shorter fibers. Cotton with better Favimat elongation distributions tended to have better length distributions. The impact of environmental stress was not noted in most HVI properties, particularly fiber strength, but was apparent with elongation. Tensile data between HVI and Favimat correlate well, but some findings were only apparent through evaluating the Favimat data, which suggests that depending on the goal of a project, Favimat data may provide additional value. Results indicate that fiber elongation, whether measured through HVI or Favimat, plays a critical role in work-to-break, challenging the prevailing focus on fiber strength. Compared to elongation, the narrow range of fiber strength among commercial varieties suggests a higher potential for enhancing elongation rather than strength, with substantial impacts on work-to-break. Improvements in fiber elongation allow the fiber to withstand environmental and mechanical stress, helping to preserve the fiber length distribution.

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