Fiber Quality Parameters Research Articles

TAM BB‐2139 ELSU extra long staple upland germplasm

AbstractThe minimum or nondiscount upper half mean length (UHML) of upland cotton, Gossypium hirsutum L., for consumption in the United States is 27 mm, while the minimum for international markets is 28 mm. This discrepancy is based on the remaining US spinning mills predominately using rotor spinning technology, while ring spinning predominates internationally. Along with increased international base for staple length, processors desire greater fiber strength, decreased short fiber content, and more uniform fiber length distributions to withstand ever‐increasing processing speeds and rigor and to produce premium yarns with improved end use quality. A narrower micronaire range (or finer yet mature fibers) or finer fibers is also desirable. With increasing export of US cotton and advances in spinning technology, improvements of fiber quality parameters are essential for the competitiveness of US upland cotton. Producers receive premiums for improved fiber quality, and their product is more competitive with manmade fibers in the textile market. TAM BB‐2139 ELSU (extra long staple upland) (Reg. no. GP‐1071, PI 691840) exhibited UHML exceeding the control cultivars and averaged 35.5 mm UHML across six locations in central and south Texas in 2016–2017. It also averaged 36.6 mm in the 2016 USDA Regional High Quality Test when grown across nine locations in eight states. The minimum UHML for G. barbadense L., pima cotton, is 34.9 mm. TAM BB‐2139 ELSU will provide upland cotton breeders with a source for improving UHML.

The prediction of quality characteristics of cotton/elastane core yarn using artificial neural networks and support vector machines

Core yarn is a type of yarn that has a filament fiber in the center with a different fiber wrapped around it. This type of yarn is of growing importance in the textile industry. It is important to predict the quality characteristics of a core yarn before production to prevent the faulty production of fabrics. Therefore, the development of predictive models is a necessity in the textile industry. In this study, artificial neural network (ANN) and support vector machine (SVM) models are proposed to predict the quality characteristics of cotton/elastane core yarn, using fiber quality and spinning parameters. Principal component analysis and analysis of variance techniques are also used to reduce input dimensions, since high dimensional data may reduce a model’s potential for success in prediction. The prediction models are trained and tested using the data obtained from a textile production plant. The results of all the models are compared with each other on test data. Mean absolute percentage error (MAPE), mean absolute error (MAE) and correlation coefficient (R) are used to assess the prediction power of the models. Although on most of the tests SVM models fared slightly better than ANN models, both models provide accurate predictions for most of the yarn quality characteristics. The results show that the best models have over 90% success rate in MAPE and R. In particular, the Coefficient of Variance of mass (CVm) along the yarn, hairiness and Reisskilometer quality characteristics of the cotton/elastane core yarn are predicted with 91%, 93% and 95% accuracy, respectively.

Non–2,4-D–resistant cotton response to glyphosate plus 2,4-D choline tank contamination

AbstractField trials were conducted near Lubbock, TX, in 2013, 2014, and 2015 to evaluate non–2,4-D–resistant cotton response to low rates of glyphosate plus 2,4-D choline. Cotton was treated with five rates of glyphosate plus 2,4-D choline (0.0183, 0.183, 1.83, 18.3, and 183 g ae ha−1) at two application timings (nine leaf and first bloom). These rates correspond to contamination rates of 0.0008%, 0.008%, 0.08%, 0.8%, and 8%, respectively. Visual cotton injury, boll retention, lint yield, and fiber properties were recorded. When averaged over contamination rates, visual injury after applications made to nine-leaf cotton was greater than for first-bloom cotton in three of 3 yr and yield loss was greater when applications were made to nine-leaf cotton when compared with first-bloom cotton in two of 3 yr. Averaged over application timing, lint yield in 2013, 2014, and 2015 after glyphosate plus 2,4-D choline contamination rates of 0.0008% and 0.008% were not different than that of the nontreated control, whereas contamination rates of 0.08%, 0.8%, and 8% decreased yield by 3% to 20%, 45% to 58%, and 80% to 96%, respectively. Contamination rates of 0.0008%, 0.008%, 0.08%, and 0.8% rarely affected fiber quality; however, a contamination rate of 8% frequently decreased micronaire, fiber length, fiber length uniformity, and fiber strength. This decrease in fiber quality also resulted in a reduction in cotton loan value and potential financial return. Although decreases in fiber quality parameters were not observed with the 0.8% contamination rate, significant reductions in financial return occurred due to yield loss caused by injury from glyphosate plus 2,4-D choline.

Bi-directional prediction of wood fiber production using the combination of improved particle swarm optimization and support vector machine

In order to investigate the relationship between production parameters and evaluation indexes for wood fiber production, a bi-directional prediction model was established to predict the fiber quality, energy consumption, and production parameters based on the improved particle swarm optimization and support vector machine (IPSO-SVM). SVM was applied to build the bi-directional prediction model, and IPSO was used to optimize the SVM parameters that affect the performance of prediction greatly. In the case of the forward prediction, the model can predict the fiber quality and energy consumption using the production parameters as input information; in the case of the backward prediction, the model can estimate production parameters using the fiber quality and energy consumption as evaluation indexes for input information. The results showed that the IPSO-SVM model had high accuracy and good generalization ability in the prediction for the wood fiber production. Additionally, based on the effectiveness of the proposed model and preset evaluation indexes, the corresponding production parameters were determined, which was able to save the wooden resources as well as reduce energy consumption in the fiberboard production.

Early maturing Bt cotton requires more potassium fertilizer under water deficiency to augment seed-cotton yield but not lint quality

Exhaustive crops such as cotton require potassium (K) in copious amounts as compared to other crops. High yielding cultivars in cotton-wheat cropping system, have further increased its demand in cotton growing areas of Pakistan. As cotton is grown in arid and semiarid areas, therefore often prone to water deficiency. The reproductive growth particularly flowering and boll setting are highly sensitive to low soil water potentials, where enough K supply can play a vital role. In this two-year field studies, three cultivars (early, mid and late maturing) were cultivated at two K fertilizer levels 100, 200 kg K ha−1 along with control with no K fertilizer application at two irrigation levels. In first irrigation level, water was applied as per full irrigation schedule, while in water deficit irrigation water was applied at deficit irrigation schedule started after flowering till harvesting. It has been revealed that K application has impact on boll setting as well as seed cotton yield, however early and mid-maturing cultivars are more responsive to K fertilization. Furthermore, irrigation level had significant impact against K fertilization and relatively better response was observed in deficit irrigation as compared to full irrigation. Nevertheless, fiber quality parameters were unaffected by K fertilization. Considering the best benefit cost ratio under water deficiency, it is concluded that 100 kg K2O ha−1 should be applied at the time of seed bed preparation for economical seed-cotton yield of early maturing Bt cotton.

Planting Date Effects on Cotton Lint Yield and Fiber Quality in the U.S. Southern High Plains

Cotton planting date effects in the U.S. Southern High Plains (SHP) were evaluated based on 11 years of May-planted and June-planted irrigated variety trials. Multiple cultivars planted in each year’s trial allowed for the calculation of 153 yield effects and 162 effects in 5 fiber quality parameters. Yield and quality effects were considered in the context of related changes in total growing season degree days (GDDS) and total cool hours (CHRS) during a boll formation period 80 to 110 days after planting. May planting increased GDDS and significantly increased yields in 8 of 10 years that comparisons could be made. Micronaire and fiber elongation were the most sensitive quality parameters to planting date. June planting resulted in increased CHRS every year and a significantly higher incidence of low micronaire in 7 of 11 years. In 7 of 11 years May planting significantly reduced fiber elongation relative to June planting. Analysis of SHP temperature data show that late-April to early-May planting dates may increase yield and micronaire by maximizing GDDS and minimizing CHRS. Although this practice may be optimal to the SHP environment it may also require high-vigor seed and pre-planting irrigation. Adapting genetics to an early planting strategy might include selecting for improved seed vigor and cold germination with acceptable yield and fiber quality traits.

Characterizations of male sterility in a glyphosate-tolerant upland cotton (Gossypium hirsutum L.) induced by glyphosate and its assessments on safety utilization

Productivity of hybrid cottonseed by steady male sterile line is considered as an effective strategy in heterosis utilization. The male sterility was obtained by glyphosate application on transgenic glyphosate-tolerant (TGT) cotton line GRR, and its phenotypes were stable and apparent from previous primarily study. Systematic characterizations and safety assessments on the male sterility must accelerate its utilization and release in hybrid cottonseeds productions. In this study, featured characteristics in the male sterility were revealed from morphological phenotype, microsporogenesis, expressing pattern of exogenous G6-EPSPS mRNA, antioxidant enzymes response. Additionally, safety assessments on the male sterility obtained from GRR, based on outcrossing rate test, yield and fiber quality traits, in comparison with conventional manual emasculating, which were conducted for 3 seasons. The results indicated that the male sterile is stable with typical characteristics as following: (1) shorter and fusion filaments, larger distance between androecium and stigma, and anther indehiscence; (2) pre-degradation on tapetum and “cavitation” pollen during microsporogenesis; (3) Higher increasing expression efficiency of G6-EPSPS, as much as approximate 8 times, in pistil versus stamen in GRR-GT (GRR after glyphosate) was revealed, comparing with the control GRR (4) APX activity increased in stamens while decreased in other organs, in GRR-GT versus GRR. GRR-GT is safe as complete abortion and capable in cotton heterosis utilization, since there were no negative effects on F1 yield traits and significance in fiber quality parameters, in comparison with conventional manual emasculation. In details, the all fiber lint yields and Micronaire values ranged from 1536.80 ± 115.64 to 1883.90 ± 18.58 kg/ha and 4.60 ± 0.10 to 5.10 ± 0.79 respectively.

Impacts of Irrigation Termination Date on Cotton Yield and Irrigation Requirement

Optimization of cotton irrigation termination (IT) can lead to more efficient utilization and conservation of limited water resources in many cotton production areas across the U.S. This study evaluated the effects of three IT timings on yield, fiber quality, and irrigation requirements of irrigated cotton in southwest Oklahoma during three growing seasons. The results showed cotton yield increased with later IT dates, but this response was highly dependent on the amount and timing of late-season precipitation events. Only a few fiber quality parameters were significantly different among treatments, suggesting a more limited impact of IT on fiber quality. When averaged over the three study years, the lint yield was significantly different amongst all treatments, with an average increase of 347 kg ha−1 from the earliest to the latest IT. Additionally, the seed yield and the micronaire were similar for the two earlier IT treatments and significantly smaller than the values under the latest IT treatment. The differences in fiber uniformity and strength were also significant amongst IT treatments. Strong positive relationships were found between yield components and average late-season water content in the root zone. Lint and seed yields plateaued at an average late-season soil matric potential of about −30 kPa and had a quadratic decline as soil moisture depleted. When benchmarked against the latest IT treatment, the earlier IT treatments achieved average reductions of 16–28% in irrigation requirement. However, this water conservation was accompanied with considerable declines in yield components and micronaire and smaller declines in fiber length, uniformity, and strength.

Evaluation of Early Season Foliar Fungicide Applications to Support Non-Fungicidal ‘Plant Health’ Benefits

The recent labeling of a new fungicide and rumors of non-fungicidal ‘plant health’ benefits achieved through early-season foliar applications of certain fungicides have led to inquiries concerning the practice. The objective of this research was to determine the impact of an early-season fungicide application on early-season growth or end-of-season lint yields, turnout, and/or fiber quality when disease symptoms are not present. During the 2014-2016 growing seasons, a total of ten trials were established in Alexandria, LA; Starkville, MS; Fort Cobb, OK; Jackson, TN; and Snook, TX. Fungicide treatments included an untreated control, a foliar application of 0.11 kg ai ha-1 zoxystrobin, and a foliar application of 0.07 kg ai ha-1 fluxapyroxad + 0.15 kg ai ha-1 pyraclostrobin. All treatments targeted the two through four true leaf growth stage. A significant interaction between fungicide treatment and site-year was observed from node counts collected at 14 and 28 DAA. Site-year analysis indicated a significant reduction in node counts observed with the azoxystrobin treatment in one site-year in the 14 DAA data and one site-year in the 28 DAA data. Fungicide treatment did not impact plant height or vigor ratings collected at 14 or 28 DAA, chlorophyll meter readings, lint yield, turnout, or fiber quality parameters in any site-year. Failure of fungicide treatments to positively impact in-season growth measurements, yield, and yield parameters suggests the evaluated fungicides should not be applied early-season for the purpose of improving ‘plant health’ and should instead be reserved to target above-threshold levels of disease incidence/severity.

1-Methylcyclopropene Effects on Field-Grown Cotton: Morphological Characteristics and Yield

Upland cotton (Gossypium hirsutum L.) is an important socioeconomic crop throughout most of the southern U.S. In Texas, cotton is the lead cash crop and its productivity is often limited by abiotic stress events such as drought and elevated ambient temperatures. The objective of this study was to assess the effects of 1-methylcyclopropene (1-MCP) applications triggered by canopy temperature and forecasted ambient temperatures on field-grown cotton plants. Yield and crop morphological responses to 1-MCP applications were investigated in field studies conducted during the summers of 2012 to 2014 at the Texas A&M University Field Laboratory in Burleson County, TX. Positive effects of 1-MCP were found for fruit retention in 2013 and 2014 for both irrigated and dryland studies; however, a negative impact was found in the 2012 irrigated study. By harvest, 1-MCP applications had no effect on final cotton yield or fiber quality parameters. Applications of 1-MCP affected some morphological characteristics of cotton plants; however, it did not improve crop yield.

Optimization of single locking cotton feeder for maximizing ginning output and minimizing specific energy of double roller gin

The aim of the study was to improve the efficiency of the double roller cotton gin in terms of ginning output and energy consumption. Therefore a spike cylinder–type gin feeder with the concept of single locking of cotton bolls was developed and optimized. The speed of the spike cylinder of the single locking feeder and cotton moisture were optimized using response surface methodology for long and medium staple cotton. Ginning output of the double roller gin was maximized and the specific energy requirement for ginning was minimized during optimization. Quadratic models were fitted for prediction of ginning output and specific energy. Optimum cotton moisture of 7.38 and 7.15% and optimum spike cylinder speed of 307 and 297 rpm with desirability of 0.9185 and 0.8923 were arrived at using multiple regression analysis for long and medium staple cotton, respectively. Use of the single locking cotton feeder for long and medium staple cotton resulted in a 22 and 25% increase in ginning output, respectively, and a 12 and 13.5% reduction in specific energy requirement, respectively, compared to the conventional system, the auto-feeder. The single locking feeder showed significant improvement in the color grade of cotton. Other high volume instrument and advanced fiber information system fiber quality parameters remained unaffected.

Evaluating Within‐Plant Variability of Cotton Fiber Length and Maturity

Core Ideas Cultivars showed differences for the within‐plant fiber length and maturity.Some cultivars exhibited relatively stable within‐plant fiber length and maturity.Genetic component plays a significant role for the differences among the cultivars. Previous studies have indicated differences in fiber quality parameters including fiber length and maturity within the canopy of cotton (Gossypium hirsutum L) plants. A 3‐yr study was conducted to investigate the impact of within‐plant variability on fiber length and maturity of upland cotton cultivars widely grown on the High Plains of Texas. Twelve upland cotton cultivars were grown in a randomized complete block design with three field replications, in Lubbock, TX, during the 2012, 2013, and 2014 growing seasons. A box‐picking harvesting method was used to individualize samples so that the within‐plant variability of cotton fiber quality could be studied. Bolls harvested from different positions on the plants were ginned with a tabletop roller gin to minimize fiber damage. The lint from each fruiting position was blended with a supple needles laboratory blender to reduce within‐sample variability while minimizing fiber breakage. Each sample collected from a different fruiting position on the plant was tested on the Advanced Fiber Information System (AFIS) with three replications of 3000 fibers. The results indicated that cultivars such as FM 9170 B2F, NG 4111 RF, PHY 499 WRF, and FM 2484 B2F showed lower within‐plant variability, while DP 1044 B2RF, PHY 367 WRF, and ST 5458 B2F showed relatively high within‐plant variability for AFIS fiber length and fiber maturity. In conclusion, variations in within‐plant fiber length and maturity among upland cotton cultivars could be a potential source of variability for breeding programs aimed at improving fiber quality.

Combining ability and heterosis analysis for fibre yield and quality parameters in roselle (Hibiscus sabdariffa L.)

Roselle (Hibiscus sabdariffa L.) is second important bast fibre crop after jute in India. With an aim to ex-ploit non-additive genetic variance present experiment was designed to identify good general combining parents and specific cross combination for fibre yield and fibre quality parameters (fibre fineness, fibre tenacity) in roselle. A total of 11 parents were crossed in complete diallel fashion which resulted 55 F1, 55 RF1 (reciprocal F1). Parents, F1s and RF1s were grown in randomized block design. Analysis of variance revealed significant differences (P< 0.01, P<0.05) among the parents and their hybrids. The parents AMV 1, AMV 5, GR 27 and AHS 160 were identified as good combiners since they recorded significant general combining ability (GCA) effects for fibre yield and quality parameters. Further, For fibre yield only three crosses (AMV 1 × AMV 4, AMV 1 × GR 27, HS 4288 × JRR 07) showed significant specific combining ability (SCA) effects from them hybrid AMV 1 × GR 27 (fibre yield=27.37g/ plant) exhibited positively significant best parent (Non bris 4, Mean fibre yield=21.16g/plant) heterosis (29.35%). Similarly, for fibre tenacity, hybrid GR 27 × JRR 07 (fibre tenacity=23.47g/tex) exhibited positively significant best parent (HS 4288; fibre tenacity=20.35g/tex) heterosis (15.30%).

Registration of ‘Tamcot G11’ Upland Cotton Cultivar

‘Tamcot G11’ upland cotton (Gossypium hirsutum L.) cultivar (Reg. No. CV‐135, PI 682743) was developed by Texas A&M AgriLife Research and released in 2017 as part of an ongoing effort to create cultivars and germplasm with combinations of improved fiber quality parameters, especially upper half mean length (UHML) and fiber bundle strength. Tamcot G11 is a conventional cultivar that is competitive in lint yield potential with current upland cultivars available for production in central and south Texas. Tamcot G11 exhibited significantly longer UHML, measured by high volume instrument (HVI), than the average of all comparison cultivars in 16 of 17 performance trials across central and south Texas during 2013 through 2016. Micronaire of Tamcot G11 was within the premium range in 12 of the 17 performance trials, while the control cultivars averaged the premium range in only 3 or the 17 trials. Strength of Tamcot G11 and the mean of all controls were equal in all except two trials, whereas Tamcot G11 tended to have lower fiber elongation at break. Lint yield of Tamcot G11 was equal to or greater than the average of all control cultivars in 16 of the 17 trials. Lint percentage of Tamcot G11 was acceptable yet below that of most current upland cultivars. Tamcot G11 provides producers with a competitive, high‐quality conventional cultivar with UHML sufficient to reduce the probability of discounts based on fiber length.

Development of superior hybrids for fibre quality based on heterosis and combining ability in upland cotton (Gossypium hirsutum L.)

The cultivated Gossypium spp. represents the most important, natural fibre crop in the world. Breeding for high cotton yield is still the primary goal of cotton breeding programs, but improving fibre quality has become increasingly important. The enhancement of fibre quality traits like fibre length, strength, and fibre fineness is an essential requirement for the modern textile industry. The objective of this study was to facilitate the selection in cotton breeding program and estimate the general combining ability (GCA) of the parents and specific combining ability (SCA) of hybrids considered for the development of high yielding and better fiber quality in early generations. The study was carried out at cotton research area, CCS Haryana Agricultural University, Hisar (India) during 2014 and 2015 kharif season. Fifteen cotton lines (which have maximum diversity) and four testers (which are known as well adapted and high yielding) were crossed in a line x tester mating design in 2014. Nineteen genotypes and 60 F1 hybrids were planted in the randomized complete block design with three replications at the same experimental area in 2015. The ratio of δ2 GCA /δ2 SCA was less than unity for all the nine characters indicating preponderance of non-additive gene action (dominance and epistasis), which is an important in exploitation of heterosis through hybrid breeding. The best general combining ability was detected from the parent H1470 for seed cotton yield, H1464 and H1098-i for fiber quality traits. SCA was significant for AC726 x H1236, ISR12 x H1226, HR1 x H1117 hybrid combinations for yield and fiber quality. The crosses H1470 x H1236 and H1470 x H1098-i were reported good heterosis for seed cotton yield as well as for fibre quality, selected the best hybrids were H1464 x H1098-i and H1463 x H1226. These cross combinations involved at least one parent with high or average GCA effect for a particular trait. The cross combination involving H1470, H1098-i and H1464 parents’ recorded significant positive heterosis with acceptable SCA effect for both yield and fibre quality parameters. This investigation concluded that the parents H1470, H1098-i and H1464 can be used in hybrid development programme with better fibre quality.

English

The quality of cotton fibers in Brazil has been studied. This was done by studying the fiber samples obtained from bolls removed from the middle third of the plants. These fiber samples are referred to as “standard sample”. This way to collect fiber data requires lots of labor, and may disguise the results obtained in experimental appraisals, due to human errors in gathering boll. Besides, cotton yield and quality is influenced by water availability, especially during abiotic tests with water deficit, in which, fiber quality samples may be affected by boll position. Thus, the objective of this study was to evaluate the influence of sampling method on the technological characteristics of cotton fibers, in irrigated and water stress tests at different stages of the crop cycle. Two methods were made to collect cotton fiber. The first method was the standard sample and the second way was gathering sample of bolls in randomized position, through all experimental plot (called randomized sample). The results show that the analysis performed by standard sample tend to overestimate the values of the fiber quality parameters, differing from the results obtained with the randomized sample that is representative of all plot. It was observed that the variability of cotton fiber quality affected by water stress treatments were best represented using bolls obtained by randomized method. Consequently, in the case of experiments with water stress, the most representative method to collect cotton fiber, is through a sampling of all the plant, and not only of the middle third. Key words: Boll position, cotton fiber, HVI, standard sample, water stress.

YIELD AND FIBER QUALITY OF COTTON CULTIVARS IN RESPONSE TO SHADING

Shading is an environmental stress that affects cotton production areas, especially under tropical and rainfed conditions. The aim of this research was to evaluate the tolerance of cotton cultivars to shading. A field experiment was carried out in Primavera do Leste - MT, Brazil in the 2014 growing season. The experimental design was a 2 x 4 factorial (shading x cultivars) in randomized blocks with 4 replications. Cotton cultivars include late (TMG 82WS) and mid-early (IMA 5675B2RF, IMA 5672B2RF and IMA 5822B2RF). Shading (50% light reduction) was imposed at flowering onset (F2/F3 - Stage) for 2 weeks. Node number, boll number and fiber yield decreased by shading by 18,5, 36 and 25% on mid-early cultivars (average), respectively, as compared to the late cultivar. Boll weight was not affected by shading. For fiber quality parameters, shading reduced micronaire by 6,0 in the mid-early cultivars and fiber strength was increased by 6.4% on cultivar IMA 5672B2RF under shading and it was associated with the lowest boll number in such cultivar. It was concluded that in a season with no water or temperature limitation, the late cultivar could recovery the yield in the top of the plant. Shading decrease micronaire index, but the response depends on cultivar. Fiber properties such as length and strength were affected by shading but this response was related to the number of fruits retained by the plant.

Fiber Quality Evaluation of Pakistan’s Locally Developed Cotton Varieties for Yarn Manufacturing

ABSTRACTThis paper discusses relation between fiber quality parameters and yarn quality, presenting results of the quality assessment of Pakistan’s five popular cotton varieties. Abadgar-901 was found to have highest effective length followed by Tarzen-1 when compared to other fibers studied and the Sattari showed the least effective length. Whereas, Tarzen-1 showed highest tenacity, Sindh-1 was second to that, yet Nayab-78 showed the least strength of the studied cotton fibers. Further, it was also found that except Nayab-78, all the other cotton varieties were found to have fineness value of premium cotton standards, however, Nayab proved to be a coarse fiber, Sindh-1 was finest fiber of them all. Moreover, Sattari was found to be the whitest in color when measured for CIE and Berger whiteness index, Nayab-78 followed it just after and the Abadgar proved to be the least white compared to the studied cotton varieties.

INVESTIGATION OF HEMP (CANNABIS SATIVA L.) FIBRE QUANTITY AND QUALITY AS INFLUENCED BY GENOTYPE AND SEED RATE

The investigation on hemp fibre quantity and quality as influenced by genotype and seed rate was carried out at the Upytė Experimental Station Lithuanian of the Lithuanian Research Centre for Agriculture and Forestry in 2014. Bi-factorial trial was carried out: Factor A – variety (A1 – USO 31; A2 – Bialobrzeskie); Factor B – sowing rate (B1 – 45 kg ha-1; B2 – 70 kg ha-1). Data showed that variety (genotype) had a significant influence on fibre content (after dew-retting as well after water-retting) – it was higher for variety Bialobrzeskie and amounted to 37.2 and 34.5%, respectively. Seed rate (or crop density) did not show significant influence neither on fibre content nor on fibre quality (flexibility, strength) parameters.

The impact of fiber maturity on estimating the number of cotton (Gossypium hirsutum L.) fibers per seed surface area

The number of fibers per seed surface area (fiber density) is a selection criterion used to improve cotton fiber quality and yield simultaneously in cotton breeding programs. However, the parameters utilized to estimate fiber density are calculated from fiber quality attributes that are sensitive to environmental variations, especially fiber maturity. Fiber maturity is one of the most important fiber properties that influences other fiber properties such as individual fiber strength and length. In order to investigate the impact of within-plant fiber maturity on the estimates of fiber density, field experiments were conducted at Lubbock, Texas during the 2012, 2013 and 2014 growing seasons. A set of twelve upland cotton cultivars popular in the Texas High Plains were grown in a randomized complete block design with three field replications. Bolls were box picked at harvest to provide samples from each cultivar representing a range of fiber maturity. Fuzzy seeds obtained after roller ginning were acid-delinted, scanned on a flatbed scanner, and the WinSeedle Pro software was used to estimate the seed surface area (SSA). The number of fibers per seed was estimated using the fiber quality parameters provided by AFIS (Advanced Fiber Information System), the lint weight, and the number of seeds in the sample. The number of fibers per seed surface area was obtained by dividing the number of fibers per seed by the estimated SSA. In this study, cultivars with relatively less stable fiber maturity across the fruiting branches of the cotton plant tend to have more variable number of fibers per seed surface area estimates, suggesting that the calculation of the number of fibers per seed surface area may be biased. It is likely that the source of bias is fiber maturity (immature fibers are weak and tend to break during mechanical processing). Therefore, fiber maturity should be considered when screening lines based on estimated fiber density because low fiber maturity can lead to unreliable estimates of fiber density.