Impacts of Fiber Maturity on Spinning Performance: Controlling for Cotton Variety Dean Ethridge Thanks to the Plains Cotton Improvement Committee for funding this study.

Impacts of Fiber Maturity In the crop year, fiber and spinning tests were done on 3 varieties in 4 locations around the Southern Plains of Texas. Growing conditions resulted in a wide range of micronaire values. This provided opportunity to demonstrate the impact of fiber maturity on other fiber properties and on spinning performance.

Area of Variety Trials Variety Trials

Location 1 Low Elevation Spray Irrigation Location 2 Low Elevation Spray Irrigation Location 3 Sub-surface Drip Irrigation Location 4 Limited LEPA Irrigation Variety Trials

Drought Stress There was significant drought stress during the 2006 growing season. Adequate irrigation in locations 1 and 2 enabled normal yields. The drip irrigation at Location 3 was also adequate to overcome some of the worst effects of the drought. The irrigation at Location 4 was inadequate to compensate for the drought effects.

Drought Stress In Locations 1 and 2, there were inadequate heat units during the growing season to mature the large quantity of cotton enabled by abundant irrigation. In Location 3, heat units were also inadequate, but apparently the combination of less irrigation water and the drip irrigation system resulted in greater maturity. In Location 4, the combination of more heat units and water stress greatly reduced yields and caused the fibers to have unusually high micronaire values.

3 varieties were grown in all 4 of these locations. With the varieties known, the micronaire values reveal relative maturities at each location. Variety Trials A wide range of maturity was provided by these trials.

HVI and AFIS Test Results Fiber Properties

Micronaire 3 Varieties, 4 Locations, 2006 Crop

HVI Micronaire

Desired Range

AFIS Maturity Ratio

Fiber length distribution by number 4 Locations: Variety A

Fiber length distribution by number 4 Locations: Variety B

Fiber length distribution by number 4 Locations: Variety C

HVI Upper Half Mean Length

AFIS Upper Quartile Length

AFIS Mean Length by weight

HVI Uniformity Index

AFIS Short Fiber Content by weight

HVI Strength

HVI Elongation

AFIS Neps

Ring Spinning Test Results 40 Ne Carded Yarns 40 Ne Combed Yarns Yarn Properties

Tenacity RS 40Ne Carded

Elongation RS 40Ne Carded

CV% RS 40Ne Carded

Thin places RS 40Ne Carded

Thick places RS 40Ne Carded

Neps 200% RS 40Ne Carded

Hairiness RS 40Ne Carded

White Specks, RS 40Ne Carded

Dye Uptake, RS 40Ne Carded

Yarn Spinning Results Ring Spinning 40 Ne Combed Yarns

Combing Noils

Yarn Spinning Results Cotton cost to mill 65 cents/lb 4 leaf grade 7% waste Effective cost 69.9 cents/lb 20% noils 27% waste Effective cost 89.0 cents/lb 24% noils 31% waste Effective cost 94.4 cents/lb

Tenacity RS 40Ne Combed

Elongation RS 40Ne Combed

CV% RS 40Ne Combed

Thin places RS 40Ne Combed

Thick places RS 40Ne Combed

Neps 200% RS 40Ne Combed

Hairiness RS 40Ne Combed

Summary and Conclusions  The validity of this study is based on the fact that if we know the variety being measured, then relative micronaire values are a reliable indicator of the relative maturity of the cotton fibers.  This, in turn, reminds us that we must think clearly about the “fineness” versus the “maturity” of cotton fibers.  It is better to conceptualize “fine” fibers as being those with small perimeters, which are mature at lower micronaire values than are fibers with larger perimeters.

Summary and Conclusions  It follows that a specific (and stable) cotton variety has a “mature micronaire value” and that, in order to perform its best in textiles, it needs to reach that value.  Conversely, unless we know the variety being measured and know its mature micronaire value, we cannot accurately infer maturity from the micronaire value.

Summary and Conclusions  Under certain environmental conditions, such as drought stress, micronaire values may increase to levels that are too high for optimal textile performance.  Nevertheless, these results support the conclusion that cottons with a too-high micronaire value generally perform better than do cottons with a too-low value.

Summary and Conclusions  While immature fibers are capable of making a fairly strong bundle of fibers, each of the single fibers are weak and fragile; therefore, these fibers break under mechanical stresses, resulting in a bad length distribution ( i.e., elevated short fiber content).  This poor length distribution is the fundamental cause of the poor performance in ring spinning.  Nevertheless, for the same variety, the bundle strength for the high-micronaire fibers is greater than that for the low-micronaire fibers. (The increased numbers of fibers in the bundle does not completely compensate for the higher strength of the mature fibers.)

Summary and Conclusions  Combing of the fibers alleviates the large discrepancy in short fibers, resulting in much better relative performance of the low-micronaire samples.  However, the amount of noils at the combing stage is unacceptable for the very-low-micronaire samples.