Percentage Of Cotton Research Articles

Imidacloprid-resistant Aphis gossypii populations are more common in cotton-dominated landscapes.

Widespread reports of reduced efficacy of imidacloprid for managing cotton aphids (Aphis gossypii Glover) in cotton (Gossypium hirsutum L.) prompted an investigation to characterize the susceptibility of 43 populations over a 2-year period. The susceptibility of A. gossypii populations to imidacloprid was examined by calculating LC50 values. Further analyses related resistance assay results to a gradient of cotton production intensity. Concentration-mortality bioassays documencted populations that were 4.26-607.16 times more resistant than the susceptible laboratory population. There was a significant positive relationship between LC50 values and percentage of cotton within 2.5- and 5-km buffers surrounding collection sites. No significant relationship was detected between LC50 values and the percentage of alternative crop and noncrop hosts. Variable and high levels of resistance were detected in A. gossypii populations, and this variation was positively associated with cotton production intensity. Cotton is a host that may receive multiple applications of neonicotinoids (via seed treatment and foliar sprays) annually for seedling and mid-season pests. Rotating modes of action and limiting insecticide use should be implemented to delay the evolution of insecticide resistance in A. gossypii populations. © 2022 Society of Chemical Industry.

Contactless Detection of Moisture Content in Blended Fabrics With a Free-Space Microwave Method

The dielectric properties of cotton fabric, polyester fabric, and polyester/cotton blended fabrics with different moisture content (MC), grammage, and composition ratio were tested under 10-GHz microwave in free space. A uniform padder was developed to ensure a uniform distribution of moisture in the fabric. A power-law dielectric mixing model was then adopted and simplified to describe the MC dependence of the dielectric constant and dielectric loss factor. Two equivalent factors $K_{1}$ and $K_{2}$ , the values of which can be found in lookup tables based on surface-fitting results or calculated using regression equations taking the fabric grammage and the cotton percentage into accounting, are introduced to simplify the modeling. A prototype fabric moisture detector, consisting of a 10-GHz dielectric resonator-type oscillator, horn antenna, rectangular sample holder, detector, and digital voltmeter, was developed. A calibration equation, suitable for use in measuring the MC of cotton /polyester blended fabrics, is proposed and evaluated with different fabrics. Experimental results show that for MC in the range 0%–45% for cotton fabrics and for MC in the range 0%–35% for polyester/cotton fabrics, the coefficient of determination, the standard error of prediction, and the bias are all within acceptable ranges.

Diminishing Returns from Increased Percent Bt Cotton: The Case of Pink Bollworm

Regional suppression of pests by transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) has been reported in several cropping systems, but little is known about the functional relationship between the ultimate pest population density and the pervasiveness of Bt crops. Here we address this issue by analyzing 16 years of field data on pink bollworm (Pectinophora gossypiella) population density and percentage of Bt cotton in the Yangtze River Valley of China. In this region, the percentage of cotton hectares planted with Bt cotton increased from 9% in 2000 to 94% in 2009 and 2010. We find that as the percent Bt cotton increased over the years, the cross-year growth rate of pink bollworm from the last generation of one year to the first generation of the next year decreased. However, as the percent Bt cotton increased, the within-year growth rate of pink bollworm from the first to last generation of the same year increased, with a slope approximately opposite to that of the cross-year rates. As a result, we did not find a statistically significant decline in the annual growth rate of pink bollworm as the percent Bt cotton increased over time. Consistent with the data, our modeling analyses predict that the regional average density of pink bollworm declines as the percent Bt cotton increases, but the higher the percent Bt cotton, the slower the decline in pest density. Specifically, we find that 95% Bt cotton is predicted to cause only 3% more reduction in larval density than 80% Bt cotton. The results here suggest that density dependence can act against the decline in pest density and diminish the net effects of Bt cotton on suppression of pink bollworm in the study region. The findings call for more studies of the interactions between pest density-dependence and Bt crops.

Composition of Weave-Room Dust

Total-dust samples were collected at four weave-room sites and one card room site in each of twelve southeastern U.S. cotton mills. The cotton content of the fabrics being produced ranged from 35% to 100%. Sizings were starch, polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), and mixtures of starch PVA, starch CMC, and PVA CMC. A serial solvent extraction-gravimetric technique was developed for proximate analysis of samples. Sizing was extracted with boiling water. Iodometric methods were used to determine the extracted starch and PVA, and CMC was determined by titration of the free acid with NaOH. Weaving dust averaged 20-50% sizing, 10-30% cellulose, 0.4% synthetic fiber, and 1-4% protein. Higher total dust levels were'associated with starch sizing, increased loom speeds, and higher yarn counts. Fine dust levels increased with loom speed percentage of cotton in the product, and the use of starch as sizing. The major differences between carding and weaving dusts were the presence of sizing and the much higher average water solubility of weaving dust, 47% vs. 10%. The carding dust also contained small amounts of starch (1-2%) and protein (9-16%), plus traces of polyester in dust from card rooms in which synthetic was carded or blended simultaneously.

Oil content of cotton seed in Northern Nigeria: 1. Assessment of nuclear magnetic resonance for the determination of the oil percentage of cotton seed

SUMMARYThe oil content of a number of introduced and local varieties was determined using three nuclear magnetic resonance oil analysers at different centres and compared with results from conventional solvent extraction. Differences were evident between the three centres and between the techniques but in both cases the rankings were similar.

Oil content of cotton seed in Northern Nigeria: 2. varietal and environmental variation

SUMMARYDifferences between sites accounted for a large proportion of the variation in the oil percentage of cotton seed from variety and agronomic trials conducted in Northern Nigeria but were not consistent between seasons. Reduced oil percentages from the drier areas of the north and from later sowings suggested that length of season is an important factor but insect attack and differences in the amounts of nitrogen, potash and boron applied to the soil also contributed to the variation. Application of insecticide, potash and boron increased and nitrogen decreased oil percentages. The latter effect usually resulted from an increase in seed size without a corresponding increase in oil content. The variation in the oil percentages of commercial varieties derived from the same Nigerian Allen stock and the relatively small interactions between varieties and environments suggested that this character might be improved by selection.

A Comparison of the Carding and Processing Performance of 2.25 with 1.5-Denier Cotton/Polyester Opening-Room Blends

Various levels of cotton and polyester fibers blended during opening and picking were investigated to determine their effect on carding efficiency and processing performance. A medium staple cotton of average fiber properties and a high-modulus polyester (2.25 denier) were used in the blends. Shear friction and compression recovery of the blends increased as the percent polyester increased. For the 2.25-den polyester blends, shear friction was slightly lower and compression recovery practically the same as for 1.5-den polyester/cotton blends. Higher polyester content increased friction and cylinder load, thereby reducing carding action so that the short-term sliver variability and neps of the cotton component in the card web increased. Cylinder load and neps in the card web were lower for the 2.25 than the 1.5-den polyester blends. Higher polyester contents slightly improved yarn grade, and the grades for the 2.25-den were higher than those for the 1.5-den polyester blends. Increased friction and length uniformity of the polyester improved drafting so that second-drawing sliver, roving, and yarn uniformity improved when polyester was added to the blend. Carding waste was practically the same whether using 2.25 or 1.5-den polyester; very little polyester was lost in the waste. At constant end breakage, spinning production increased up to a 50/50 blend and then decreased as the percent of 2.25-den polyester was increased. These findings indicate that for cotton and polyester blended in the opening room, one with a high percentage of cotton can be processed more efficiently than the reverse.

SH?RANG‐SOFLĀ: THE ECONOMICS OF A NORTHEAST IRANIAN VILLAGE*

The village of Sh?‐Soflā, located in the Gorgān region of northeast Iran, has had its predominantly agricultural economy revolutionized over recent years by significant increases in the percentage of cotton, tobacco, and other cash crops planted by its peasants, paralleled by a tightening of the grip of commercial capital upon the small producer. In this paper, I propose to examine the impact of these revolutionizing changes upon the structure of the agricultural economy, using the material gathered during a field study of the village of Sh?rang‐Soflā carried out by the author in August of 1963.

The lint percentage of cotton in the Ord River Valley

Time of harvest during crop ripening was accompanied by large differences in lint percentage of cotton in the Ord River Valley. Lint percentage generally rose at least 3 per cent from first to last harvest. Varieties showed a wide range in lint percentage. Varietal values remained very stable between seasons in a three year trial but in two out of three seasons there was a pronounced time of sowing effect, lint percentage rising with sowing from November to at least February. Significant variety x time of sowing interactions were recorded. In three trials nitrogen fertilizer reduced lint percentage, though there was no consistent relationship between rate of nitrogen application and lint percentage decrease. Spacing, phosphorus, potash, and defoliation had no direct effect on lint percentage.