# Effect of Controlled Defoliant Application on Cotton Fiber Quality
## 3 Results and Discussion
### Quality Parameters Analyzes  
Micronaire provides information on the thickness of the cotton fiber's cell wall, which indicates fiber fineness and maturity. Low micronaire values indicate fine and/or immature fibers; high values indicate coarse and/or mature fibers. The fineness factor in micronaire is considered more important for spinning because it affects further processing of fiber, and fiber maturity is considered to have a significant effect on the dye-uptake process. Micronaire values between 3.8 and 4.2 were considered as desirable during early 2000 [43]. Similarly, the micronaire value of 3.5 to 4.9 is considered as MIC G5 which is standard range for good quality cotton [44]. The micronaire data from the research are within the range of good quality cotton, however, less than the overall average, and South Carolina's average data on micronaire mentioned in \"Quality summary of 2022 U.S. upland cotton--by state\" reported by cotton incorporated, which are 4.35 and 4.39 respectively [45]. Many factors affect the fiber micronaire such as planting dates, cultivar, agronomy practice, crop load [46], and weather [47]. The upper half mean length (UHML) is average length of the upper half of the longest fibers which is equivalent to staple length. It is an important quality parameter as fiber fineness and fiber tensile strength are closely related to UHML. The longer staples are usually finer and stronger than the shorter staples. The fiber properties such as UHML are reported to be affected by compact yarn spinning processes [48]. The fiber strength in the HVI system is measured in terms of force in grams required to break one tex unit of fibers when clamping in between the two sets of jaws. The data on the strength is statistically insignificant across the treatments in both fields (Tables 3 and 4). The fiber falls in the strong strength category (range is 29-30) except for the fiber from the control treatment in field 2 based on the cotton classification published by Cotton Incorporated and Cotton USA [49]. Fiber elongation is another fiber quality parameter. A positive correlation was reported between individual fiber elongation and tenacity [50]. In both Fields, the elongation of the fiber is statistically insignificant. The reflectance (Rd) and yellowness (+b) determine the color grade of the cotton fiber. Reflectance denotes the brightness of the fiber, whereas yellowness indicates the degree of pigmentation. Planting time and harvesting time have a significant role in the fiber color grade [51]. Similarly, a significant effect of reflectance and yellowness was reported on some yarn properties [52]. The HVI color chart for American upland cotton ranges from 4 to 18, and the yellowness (or pigmentation) increases with an increase in value of +b. Likewise, the reflectance ranges from 40 to 90; the higher the value, the whiter (light) will be the fiber color. Higher trash content in fiber negatively affects the fiber quality, and depending on the particle size, it can cause yarn breakage and may worsen the spinning stability. As in the delivered bale condition, the trash content of raw cotton is nearly in the range of 1-7% [53]. The trash in both fields is insignificant across the treatment. Therefore, we can apply any duty cycle safely for defoliation from the perspective of trash content. Short fiber is defined as percent by weight of fibers which is 0.5 inches or less. The presence of excess amounts of short fibers in cotton is not good for the spinner and can cause many problems, such as excess waste, weaken yarn strength, and more yarn defects [54]. Both fields have an insignificant result on short fiber index within the fields. However, if we compare the data between the two fields, field 2 has a lower SFI value than field 1. The ratio between the mean length of the fiber and the upper half mean length is known as the uniformity index of cotton fiber.