Positive relationships between plant diversity and ecosystem functioning are frequent in natural systems, however research on year-round plant diversification to improve agroecosystem outcomes is limited. Challenges such as lag times for soil health benefits during the early transition years of cover cropping may be compensated by increases in crop yield from cash crop rotations. To better understand management strategies that could promote agroecosystem productivity and sustainability, we explored responses of agronomic and soil multifunctionality to simultaneous winter cover crop mixes and cash crop rotation using a three-year field experiment in western Tennessee, USA. Cover crop treatments included a no cover crop control (winter fallow), singlespecies winter wheat (Triticum aestivum L.), single-species crimson clover (Trifolium incarnatum L.), two-species wheat-clover mix, and five-species mix of cereal rye (Secale cereale L.), oat (Avena sativa L.), clover, hairy vetch (Vicia villosa Roth), and radish (Raphanus sativus L.). Cropping systems included continuous corn (Zea mays L.), continuous soybean (Glycine max L.), corn-soybean rotation, and corn-cotton (Gossypium hirsutum L.)-soybean rotation. Total agronomic and soil health multifunctionality were weakly correlated across treatment combinations. The single-species clover and both mixes led to the highest agronomic multifunctionality in all cropping systems. Single-species wheat and wheat-clover mix provided the greatest cover crop biomass inputs, but both cover crops decreased overall cash crop yields (corn, cotton, and soybean scaled within crop and year) relative to the five-species mix. This result for yield was driven by year-one reductions in corn yield by averages of 2.15 and 1.74 Mg ha-1 in single-species wheat and wheat-clover mix cover cropped plots (respectively) compared to all other cover crop treatments. Cash crop rotation did not influence agronomic multifunctionality, although in year three, rotation with soybean increased corn yield by 1.49 Mg ha-1 yr-1 relative to monocropped corn, and rotation with corn and cotton increased soybean yield by 0.34 Mg ha-1 yr-1 relative to monocropped soybean. Wheat-clover mix as a cover crop increased mineral-associated organic C relative to winter fallow in the continuous soybean system, however there were no strong overall influences of cover crop or crop rotation on soil multifunctionality. Overall, our results suggest that winter cover crops can increase agronomic benefits of cash cropping systems in the southeastern United States within three years of adoption, but soil health benefits may be more difficult to detect in this short timeframe.

Auxin-tolerant cotton (Gossypium hirsutum, L.) cultivars are the latest tools producers use to combat herbicide-resistant weed species during the growing season. The widespread implementation of auxin-tolerant crops has led to an increase in in-season applications of auxins. Auxin drift has subsequently become a more prominent issue in the agricultural industry and causes producers to shift management tactics. Yield partitioning research based on auxin application timing has been conducted, but more information is needed concerning application rate and the interaction between application rate and timing. Experiments were conducted from 2019 to 2021 in Grand Junction, TN, to determine the effects of synthetic auxin exposure on boll positioning, development, and production. Applications of 2,4-dichlorophenoxyacetic acid (2,4-D) or dicamba were made to cotton cultivars of the opposite technology at either matchhead square or 2 weeks after first bloom (FB + 2WK). Nontreated experimental plots were also included. More severe impacts on overall lint yield, yield partitioning, and yield components were observed following exposure to 2,4-D than dicamba. Application rate and timing also impacted yield components and partitioning. Exposure to 2,4-D during vegetative growth caused increased partitioning to vegetative and aborted fruiting positions but decreased partitioning to position 1, zone 2 (nodes 9 through 12), and zone 3 (nodes 13 and above) as application rate increased. Exposure to these rates at FB + 2WK did not impact yield partitioning. Environmental conditions following applications of 2,4-D or dicamba play an important role in the recovery and growth of cotton and subsequent yield penalties.

It is essential to evaluate the genetic gain of lint yield in modern cotton (Gossypium hirsutum L.) cultivars planted in recent history and identify the trend of potential changes due to changes in breeding priorities in the United States. In National Cotton Variety Tests (NCVT) conducted since the 1960s, Upland cotton cultivars were tested annually at locations across the US Cotton Belt. The NCVT data from 1998 to 2022 after commercialization and inclusion of transgenic cotton cultivars were used to analyze lint yield trends during this period. The annual yield means were adjusted based on overlapped entries between testing years to minimize environmental influence during the long-term trials for genetic gain, which was estimated from regression of the adjusted annual means over testing years. The results showed that genetic gain of lint yield was 24.1 kg ha(-1) year(-1) during the 25-year period. When the long period was split into two segments, that is, 1998 to 2014 and 2015 to 2022, the genetic gains were 24.7 kg ha(-1) year(-1) and -1.3 kg ha(-1) year(-1), respectively. The yield trend of increasing before 2015 and plateauing after 2015 coincides with the trend of stacking technology advancement in development of transgenic cultivars. This coincidence reflects the early success of stacking technologies by seed companies in pyramiding stacked genes with cotton yield during the 2000s and the middle of 2010s. The yield plateau suggests the necessity of breakthroughs in breeding methods and biotechnologies in development of transgenic cotton for further increasing yield.

Abstract Soil physicochemical properties influence the efficacy of strategies for reducing ammonia (NH3) volatilization from urea‐based fertilizers, including fertilizer placement and the use of enhanced efficiency fertilizers (EEFs). Across the US Cotton Belt region, which spans the southern part of the country from Virginia to California and has various soil textures, little is known about how these strategies affect NH3 volatilization. Studies were conducted as a randomized complete block design using four soils from this region to evaluate the impact of surface and subsurface placement of granular urea and fluid urea ammonium nitrate, as well as EEFs, on NH3 volatilization. The EEFs were Environmentally Smart Nitrogen, N‐(n‐butyl)thiophosphoric triamide (NBPT) + Duromide, and nitrapyrin. NH3 volatilization from surface broadcast urea without EEFs was 38%–62% of applied nitrogen (N) across soils and was greatest on the soil with the highest initial pH. Subsurface urea placement reduced NH3 loss by 52%–80% compared to surface broadcast, and the greatest reduction was observed on the soil with the highest clay content. When urea was treated with NBPT + Duromide, NH3 volatilization was reduced by 3%–76% compared to urea without NBPT + Duromide, and the lowest reduction was on the soil with the lowest initial pH. These results provide new insights into N management for some agriculturally relevant soils within the US Cotton Belt, which have previously been less evaluated for NH3 losses. The findings can be used to tailor fertilizer application methods based on soil characteristics such as clay content and pH to minimize NH3 volatilization.

Interest in cotton seed size and seeding density exists due to increased seeding cost and overall decreased seed size of cotton varieties. An experiment was conducted in 2019 and 2020 in Jackson, TN, Starkville, MS, and Brooksville, MS, to determine the impact of seed size, seeding density, and variety on cotton plant development and yield. Early-season seedling vigor was impacted by seeding density and seed size. Larger seeds and higher seeding densities produced the greatest seedling vigor. Fresh weight biomass was also impacted by seed size, as larger seed produced greater fresh and dry cotton plant biomass when pooled over seeding density and variety. The greatest seed cotton yields were obtained from planting larger seed, higher seeding densities, and from 'DP 1646 B2XF'. Cotton variety and seeding density influenced financial returns and fiber quality. 'NexGen 3406 B2XF' planted at 148,200 seeds ha-1 resulted in the lowest micronaire. Net returns were not influenced by seed size or seeding density; therefore, depending on seed costs, increasing seeding densities may not be beneficial. Early season vigor was impacted by seed size and seeding density. Vigor ratings indicated that larger seeds and seeding densities produced the greatest visual vigor rating. Greatest seed cotton yields obtained by plating larger seed, greater seed density, and Delta Pine 1646 B2XF.

Crop growth and development is affected by intraspecies competition. This study was conducted to determine whether cotton productivity and profitability could be manipulated through planting geometry. The effects of row spacing, planting pattern, and variety on cotton fruit distribution, yield, and net returns were investigated near Bella Mina, AL, on a Decatur silt loam (fine, kaolinitic, thermic Rhodic Paleudults); Jackson, TN, on a Calhoun silt loam (fine-silty, mixed, active, thermic Typic Glossaqualfs); Starkville, MS, on a Leeper silty clay loam (fine, smectitic, nonacid, thermic Vertic Epiaquepts); and Stoneville, MS, on a Bosket very fine sandy loam (fine-loamy, mixed, active, thermic Mollic Hapludalfs). For both the 76- and 97-cm row spacing, transitioning from a solid to a 2 x 1 skip row pattern reduced cotton lint yield by 19%. Reduced lint yield in the 2 x 1 skip row pattern was attributed primarily to a 7% decrease in the number of Zone 1 and first-position bolls. Consequently, planting on a solid rather than skip row pattern increased net returns by 21%. Planting cotton in either 76- or 97-cm rows using a solid rather than skip row pattern likely increases crop productivity and profitability across the US cotton belt. Alternative cotton row spacings and patterns may improve net returns due to reduced input costs or greater yield.Regardless of row spacing, transitioning from a solid to 2 x 1 skip row pattern decreased cotton lint yield by 19%.Planting on a solid pattern rather than 2 x 1 skip row increased net returns by 21%.

Synthetic auxin herbicide movement onto sensitive cotton (Gossypium hirsutum L.) cultivars has impacted many US cotton hectares. The spatial scope and severity of auxin damage in-season is typically estimated by an agronomist. The use of remote sensing technology has the potential to objectively quantify the spatial scope and severity of auxin damage. Experiments were conducted in 2019, 2020, and 2021 in Grand Junction, TN, to determine: (1) the effect of reflectance data collection timing; (2) the effect of auxin exposure timing; (3) the value of near infrared and red-edge (RE) reflectance versus reflectance within the visible spectrum data; and (4) if/how visual injury relates to aerial reflectance data. Applications of 2,4-D or dicamba were made to susceptible cotton cultivars at 1X, 1/4X, 1/16X, 1/64X, 1/256X, and 1/1024X rates at either matchhead square (MHS) or 2 weeks after first bloom (FB+2WK). Non-treated controls were also included for each application timing. Aerial reflectance data were collected 7, 14, 21, and 28 days after application. Unsupervised classification of images into pixels with and without vegetation did not increase correlations between vegetation indices (VIs) and application rate. Although Vis, which generated the strongest correlations with application rate, visual injury, and relative lint yield, were generally RE based, similar correlations were also noted with visible spectrum VIs. Correlations were greater when auxin injury occurred at MHS than FB+2WK. Results suggest reflectance measured within the visible spectrum can quantify the scope and severity of auxin injury if the injury occurs early during the growing season. Remotely sensed reflectance has the potential to quantify the spatial scope and severity of synthetic auxin-injured cotton. Red-edge-based vegetation indices are most strongly correlated with application rate, visual injury, and lint yield. Similar correlations were noted with visible spectrum vegetation indices, application rate, visual injury, and lint yield. Greater correlation between injury and reflectance occurred at matchhead square than 2 weeks after first bloom. Visible spectrum reflectance can quantify the scope and severity of early-season auxin injury.

Cotton (Gossypium hirsutum L.) cultivars vary in their response to environmental factors. Recently, interest in cotton cultivars' response to varying potassium (K) fertilizer application rates and irrigation has increased. As such, the effect of cotton varieties (early and mid-maturing), K fertilizer application rates, and irrigation on cotton growth, development, and yield were investigated in Starkville, MS, on two soil mapping units (SMUs): a Leeper silty clay loam (LSCL) and a Marietta fine sandy loam (MFSL). Cotton plant height was positively correlated with SMU, especially LSCL, reaching 60-110 cm on average, in both irrigated and rainfed conditions. Cotton lint yield, fiber quality, and leaf K concentration responded to K and irrigation, and these responses were SMU specific. Particularly, in LSCL, the early-maturing cultivar, DP 1518 B2XF, responded to K application rate in a positive linear manner in terms of lint yield under both irrigated and rainfed conditions, whereas mid-maturing DP 1646 B2XF did not. Moreover, lint yield in irrigated MFSL soil increased with K application rate, whereas no responses were observed in rainfed conditions. These data suggest that irrigation, SMU, and cultivar combination could have an impact on K response of cotton and should be considered when making fertility recommendations or decisions. Potassium application rate and irrigation effects on early and mid-maturing cotton varieties were tested. Response to potassium and irrigation were soil mapping unit specific. Early and mid-maturing varieties responded differently to potassium application based on irrigation status.

Glyphosate has played an important role in agricultural production systems, especially after the release of glyphosate resistant crops. With increased usage and an overall reliance on chemical control, weed resistance to glyphosate has occurred and is now a major issue. The objective of this research was to investigate weed control levels provided by glufosinate, 2,4-D, and clethodim as an alternative to glyphosate. Multiple POST applications generally provided superior weed control in comparison to a single early-POST application. No programs provided greater than d after mid-POST application. Applications of glufosinate or glufosinate + 2,4-D fb clethodim + glufosinate, glufosinate + 2,4-D, or clethodim + glufosinate + 2,4-D provided adequate broadleaf weed control throughout the rating period. Although POST-only programs are an option, they are not a sustainable weed control practice. herbicides into a weed control program as well as alternative weed control methods.

Irrigation termination timing is challenging for cotton producers in humid regions, especially for fields with varying soil types. A field experiment was conducted in Jackson, TN, to investigate the best cotton irrigation termination on different soil types. The water management treatments consisted of rainfed conditions (RF) and terminating irrigation 2 weeks before the first crack boll (ITBC1 and ITBC2), at the first crack boll (ITC1 and ITC2), and 2 weeks after the first cracked boll (ITAC1 and ITAC2). The irrigation rates consisted of normal irrigation (2) and increased irrigation (1) during the 2 weeks prior to irrigation termination. Irrigation treatments were implemented on three soils: a low, an intermediate, and a high available water-holding capacity (AWHC) soil. In sandy soil, seed yield increased by 127% in 2015 with the ITAC1 treatment and by 313% in 2016 with the ITC1 treatment, compared to the control (RF). These treatments were also found to be optimal for lint yield and irrigation water productivity in their respective years. The high AWHC soil did not require any irrigation in either growing season to optimize yield. In fact, irrigating at a high rate at every termination date caused yield loss in 2015. These results indicate that cotton can benefit from later termination and higher irrigation rates when soil water and rainfall are low at the end of the growing season or be harmed when the opposite is true. In sandy soil, applying ITC1 greatly impacted seed yield compared to the rainfed crops. S3 had the highest seed and lint yield among the three different soil types. The lint quality components were not adversely affected by any termination treatment.

Cover crops have been promoted for use in agricultural systems due to both environmental and economic opportunities. Cotton (Gossypium hirsutum L.) growers in West Tennessee faced challenges in 2015 and 2016 with cover crop termination management which resulted in failed cotton stands. The objective of this experiment was to determine effects of cover crop termination timing and method on cotton emergence, development, and yield. Field experiments were conducted from 2018 to 2020 in both small plot and on-farm scenarios across West Tennessee. Cover crop termination timings consisted of an at-planting termination, 3 weeks prior to planting, and both a broadcast and furrow-strip termination 6 weeks prior to planting. The cover crop termination methods consisted of chemical termination, mechanical termination, and chemical + mechanical termination. At-planting termination reduced emergence by 25% and delayed maturity of 65% of the stand relative to a 6-week broadcast termination. Mechanical termination reduced emergence by 26% and delayed maturity of 26% of the stand relative to the chemical and chemical plus mechanical termination treatments. Thrips injury ratings were greater in cotton following a chemical + mechanical termination of the cover crop. Damage from three-cornered alfalfa hoppers (Sissistilus festinus) was less prevalent in cotton following cover crops terminated 6 weeks prior to planting in a broadcast method compared to other timings. While early season effects were observed, end-of-season yield differences were not noted. Still, producers in short season environments should be aware of the higher level of risk associated with at-planting terminations or terminations.

Cotton (Gossypium hirsutum L.) management decisions to abet early growth, fruit set, boll maturation, and harvest preparation are often facilitated by prediction of the date when critical developmental stages are reached. In the United States, growing degree days calculated with a base 60degreesF (DD60s) are commonly used to predict cotton development. Observations suggest development of modern cultivars differs from previously established guidelines. The objectives were to (1) reevaluate DD60s required for an early, mid-maturing and late maturing cultivar to reach key growth stages across the US Cotton Belt; and (2) determine if predictions of growth stages are strengthened by optimizing base temperature or including an upper threshold by growth stage. During 2018 and 2019, 22 field trials were established in 10 states. Plant growth stages were monitored weekly and air temperature was computed from interpolated surface observations weighted by a physical, geographic model. Observed DD60s to reach growth stages varied slightly by cultivar and region (<= 85 DD60s and <= 130 DD60s, respectively). Required DD60s to reach growth stages exceeded most published ranges. Optimization of base temperature and inclusion of an upper threshold by growth stage did not substantially decrease errors in predicting date of growth stage occurrence. The DD55 and DD55 with an upper threshold of 86degreesF calculations resulted in slightly lower errors in predicting date of growth stage occurrence than the DD60 calculation. Although guidelines should be updated, it is unlikely slight modification in base temperature or upper thresholds will drastically increase the predictive ability over the DD60 calculation.

Cotton (Gossypium hirsutum L.) is often grown in climates of intermittent drought conditions. Plants that limit transpiration rates (TRs) when initially exposed to water-deficit stress will preserve water for use later during critical growth stages. Two traits resulting in conservative TRs are TR limitations under soil drying and high vapor pressure deficit (VPD, >2.5 kPa). The objective of this study was to assess the performance of four contrasting cotton cultivars and their TRs under induced water stresses. Three studies were conducted to test (i) the early stomatal closure under soil drying in a greenhouse, (ii) the TR to varying VPD levels in a growth chamber, and (iii) the stomatal conductance (gs), wilting score, specific leaf area (SLA), relative water content (RWC), and yield in an extreme field environment. Significant differences in the fraction of transpirable soil water threshold (FTSW threshold) were detected among cultivars in the greenhouse. The FTSW threshold among cultivars ranged from 0.29 to 0.39. Under varying VPD levels, only PHY 400 W3FE expressed a limited TR (TRlim) with increasing VPD at 1.6 kPa. In the field study, differences in gs, wilting score, RWC, SLA, and lint yield were observed among cultivars within the water limited treatments (i.e. rainout and rainfed). PHY 400 W3FE had the lowest wilting score compared to other cultivars. Under the rainout treatment, PHY 400 W3FE yielded 37% higher than PHY 500 W3FE. Results indicate a trend in water saving potential among cotton cultivars, given the differences in their TR sensitivity to water-deficit stress conditions.

Potassium (K) deficiency in cotton (Gossypium hirsutum L.) grown on soils with adequate soil test K levels has become more prevalent. Field experiments were conducted with or without irrigation as the main plot and K fertilizer rates as subplot treatments. Granular K was applied preseason at rates of 0, 45, 90, 134, 179, and 224 kg K ha(-1). Two in-season foliar K programs applied a total of either 2.8 or 5.6 kg K ha(-1) were included to compare against the check. Experiments were set up on two distinct soil mapping units (SMUs) in Starkville, MS, including a Leeper silty clay loam (LSCL; fine, smectitic, nonacid, thermic Vertic Epiaquepts) and a Marietta fine sandy loam (MFSL; fine-loamy, siliceous, active, thermic Fluvaquentic Eutrudepts). Response variables collected include lint yield and fiber quality, leaf K concentrations, and cotton growth and development parameters. Across all years of the experiment, LSCL lint yields increased at a rate of 41 and 118 kg ha(-1) per 45 kg K ha(-1) under rainfed and irrigated conditions, respectively. On the MFSL, lint yield increase was not significant for either rainfed or irrigated conditions. Leaf K concentrations at first bloom and 4 weeks after first bloom responded quadratically to K rate, with peak leaf K concentrations occurring between 134 and 179 kg K ha(-1). Differences in cotton growth parameters were observed; however, differences were likely physiologically insignificant. For all parameters, foliar K application programs did not differ from the untreated check. This investigation showed that foliar K application alone are insufficient, and responses to granular K and irrigation were dependent on SMUs.

Background Cotton ( Gossypium hirsutum L.) is often grown in locations characterized by high atmospheric evaporative demand. It has been hypothesized that plants which resist hydraulic flow under this condition will limit water use and conserve soil water. Therefore, in a series of controlled environment experiments ten cotton cultivars were exposed to two different temperature and vapor pressure deficit (VPD) conditions (i.e., 38 °C, > 3 kPa and 32 °C, 1∼1.5 kPa) as well as a progressive soil drying. Then, individual differences in shoot hydraulic conductance (K shoot ) was measured using a hydraulic conductance flow meter (HCFM). Physiological parameters were reported included leaf area, dry leaf weight, stomatal conductance (g s ), and water use efficiency coefficient (WUE k ). Results Differences were observed in K shoot among cultivars under the 38 °C, > 3 kPa but not the 32 °C, 1∼1.5 kPa environment. Under the 38 °C, > 3 kPa environment, correlations were found between K shoot , stomatal conductance (g s ), VPD breakpoint, WUE k , total leaf area, dry leaf weight, fraction transpirable soil water (FTSW) threshold, and slope of TR decline after FTSW threshold. Conclusion Results show that the ability of some cotton cultivars to restrict water loss under high evaporative demand through early stomatal closure is associated with the cultivars’ K shoot . The K shoot is influential in the limitation of TR trait under high temperature and VPD.

The widespread adoption of smartphones and unmanned aerial vehicles (UAVs) has the potential to ease collection of in-season cotton nitrogen (N) status. Subsequently, in-season cotton N status could be used to drive management decisions. The utility and limitations of these new platforms must be assessed and compared to current in-season measurements. The objectives of this study were to evaluate the ability of early- and late-season ground-based measurements to provide insight into cotton N status and to evaluate the ability of aerial-based measurements to correlate to ground-based measurements. Although measurements failed to correlate strongly across seasons to leaf N, moderate relationships (R2 = 0.453) between chlorophyll meter readings and the dark green color index (DGCI) measured from a smartphone were observed in late-season measurements. Poor relationships were found between early-season UAV-acquired vegetation indices (VIs) and leaf N. Analysis of a subset of the data indicated relationships between chlorophyll meter readings and chlorophyll concentrations predicted by DGCI were strong for ground-based measurements and moderate for UAV-based measurements. (R2 = 0.711 and R2 = 0.511, respectively). Although additional site-years including aerial-based data are needed, this study demonstrates the usefulness of UAV-based reflectance data and VIs in predicting in-season cotton N status. Furthermore, it appears handheld DGCI measurements have the potential to replace chlorophyll meter readings for late in-season measurements of cotton N status.

Poor soil health purportedly limits crop yield and on-farm profitability in environments with a history of intensive tillage. Research was conducted to determine if cover cropping improves basic soil physical properties, crop productivity, and economic parameters in conventionally tilled soils. The effects of irrigation and cover crop species on bulk density, water infiltration rate, cotton yield, and net returns were evaluated on a Dundee silty clay loam (Fine-silty, mixed, active, thermic type Typic Endoqualfs) near Tribbett, MS in 2017 and a Leeper silty clay loam (fine, smectitic, nonacid, thermic Vertic Epiaquepts) near Starkville, MS from 2017 through 2018. Relative to the fallow production system, cereal rye and crimson clover decreased bulk density 4.6% but had no effect on water infiltration rate. Pooled over year and location, cover crop had no effect on lint yield in either irrigated or non-irrigated environments. However, transitioning from conventional to a cover crop system reduced net returns for cotton $50.22/ha to $307.87/ha on average. Our data indicate that while transitioning from a conventional to a fall cover crop production system, modest improvements in some soil physical properties due to cover crop establishment will not increase cotton productivity but will decrease net returns.

Automation continues to play a greater role in agricultural production with commercial systems now available for machine vision identification of weeds and other pests, autonomous weed control, and robotic harvesters for fruits and vegetables. The growing availability of autonomous machines in agriculture indicates that there are opportunities to increase automation in cotton production. This article considers how current and future advances in automation has, could, or will impact cotton production practices. The results are organized to follow the cotton production process from land preparation to planting to within season management through harvesting and ginning. For each step, current and potential opportunities to automate processes are discussed. Specific examples include advances in automated weed control and progress made in the use of robotic systems for cotton harvesting.

The environmental impact of genetically modified crops has been extensively investigated. However, few reports on the influence of transgenic traits on genetic structure have been reported in the literature. It is unknown how or if transgenic cultivars have affected genotypic variation in upland cotton (Gossypium hirsutum L.) since its rise to dominance in cotton production. In this study, the genotypic variance components, g, of lint yield (LY) and fiber quality were compared among transgenic and nontransgenic cotton in the USDA Regional High Quality (RHQ) tests from 2002 through 2018. The popular transgenic and nontransgenic cultivars/lines developed by the major private and public cotton breeding programs in the United States during this period were included. Testing cycles within the RHQ protocol consist of standardized control cultivars plus experimental entries. Variance components were dissected in each testing year within six such testing cycles. Lint yield of the transgenic cotton was generally higher than nontransgenic cotton. Fiber quality of the nontransgenic cotton was generally higher than the transgenic cotton. For LY, the proportion of g to the total variance was lower in the transgenic cotton than in the nontransgenic cotton, but the difference diminished in the recent two cycles. The proportion of g was lower in the transgenic cotton compared with the nontransgenic cotton for fiber length, fiber strength, fiber uniformity, and micronaire. The discrepancy between the two types of cotton in the RHQ tests reflects the influences of differential breeding schemes in the private and public breeding programs on means and genotypic variance of LY and fiber quality.