Higher Lint Yield Research Articles

Registration of Four Germplasm Lines of Upland Cotton with High Lint Yield

Four upland cotton (Gossypium hirsutum L.) lines, NC18‐07 (Reg. no. GP‐1052, PI 690767), NC18‐08 (Reg. no. GP‐1053, PI 690768), NC18‐09 (Reg. no. GP‐1054, PI 690769), and NC18‐10 (Reg. no. GP‐1055, PI 690770), were developed by the Department of Crop and Soil Sciences at North Carolina State University. The four upland cotton lines have improved yield production and some good fiber quality traits. All four lines were derived from a random mated population using multiple parental lines. These four lines were compared with commercial check cultivars ‘DP393’, ‘Sure‐Grow 747’, and ‘UA48’ over 2 yr in Clayton, NC. NC18‐07 produced 7.6 to 34.2% greater lint yields than that of the checks and had 15.2% greater elongation value than that of UA48. NC18‐08 produced 5.9 to 32.1% greater lint yield than the checks. NC18‐09 yielded 2.2 to 27.5% greater lint than checks and showed 44.7 and 22.3% greater elongation values than that of UA48 and parental lines, respectively. Germplasm line NC18‐10 produced 1.0 to 26.0% greater lint yield than the commercial checks and also displayed 26.5 and 7.0% greater elongation values than that of UA48 and parental lines, respectively. These lines could be valuable sources for cotton breeding and programs focusing on improving yield as well as fiber elongation.

Genetic Detection of Lint Percentage Applying Single-Locus and Multi-Locus Genome-Wide Association Studies in Chinese Early-Maturity Upland Cotton.

Upland cotton (Gossypium hirsutum L.) is the most important source of natural fiber in the world. Early-maturity upland cotton varieties are commonly planted in China. Nevertheless, lint yield of early-maturity upland cotton varieties is strikingly lower than that of middle- and late-maturity ones. How to effectively improve lint yield of early maturing cotton, becomes a focus of cotton research. Here, based on 72,792 high-quality single nucleotide polymorphisms of 160 early-maturing upland cotton accessions, we performed genome-wide association studies (GWASs) for lint percentage (LP), one of the most lint-yield component traits, applying one single-locus method and six multi-locus methods. A total of 4 and 45 significant quantitative trait nucleotides (QTNs) were respectively identified to be associated with LP. Interestingly, in two of four planting environments, two of these QTNs (A02_74713290 and A02_75551547) were simultaneously detected via both one single-locus and three or more multi-locus GWAS methods. Among the 42 genes within a genomic region (A02: 74.31–75.95 Mbp) containing the above two peak QTNs, Gh_A02G1269, Gh_A02G1280, and Gh_A02G1295 had the highest expression levels in ovules during seed development from 20 to 25 days post anthesis, whereas Gh_A02G1278 was preferentially expressed in the fibers rather than other organs. These results imply that the four potential candidate genes might be closely related to cotton LP by regulating the proportion of seed weight and fiber yield. The QTNs and potential candidate genes for LP, identified in this study, provide valuable resource for cultivating novel cotton varieties with earliness and high lint yield in the future.

Sowing Density Effects in Cotton Yields and Its Components

Evaluation of sowing density is an important factor for achieving maximum yields without affecting other agronomic traits. Field experiments were conducted during three consecutive years (2008, 2009 and 2010) to determinate the effect of four sowing density (62,500; 83,333; 100,000 and 142,857 pl ha−1) on yields and its components of two cotton varieties, ‘Delta Pine 16′ and ‘SN-290′ in Venezuela. The traits evaluated were lint yield, boll weight, number of seeds per boll, 100-seed weight, and fiber content. Highly significant differences (p ≤ 0.01) were observed among genotypes, sowing density and their interactions for all traits. Sowing density was not affected by year factor. High lint yield was found in ‘SN-290′ (4216.2 kg ha−1) at 100,000 pl ha−1; and in ‘Delta Pine 16′ (3917.3 kg ha−1) at 83,333 pl ha−1. The highest sowing density (142,857 pl ha−1), decrease lint yield and yield components in the genotypes. The highest boll weight was obtained by ‘SN-290′ with 6.4 g in average. All sowing densities evaluated resulted in lint percentages above 40%. Cotton lint yield was positively correlated with all yield components. Our results indicate that highest lint yields could be obtained with sowing densities between 83,333 and 100,000 pl ha−1 depending upon varieties used across savannahs of Venezuela.

Genetic improvement of naked-tufted seed mutants in upland cotton (Gossypium hirsutum L.)

This research evaluated the potential for using sexual crosses for genetic improvement of fiber yield, lint percent, AFIS fiber quality, and fiber initiation of two naked-tufted mutants of cotton (Gossypium hirsutum L.). The naked tufted lines were crossed with ten fuzzy breeding lines to generate 10 F2 populations. The F2 distributions were tested with Chi Square for Goodness of Fit to two monogenic and two digenetic segregation ratios. Five of the six F2 populations made with Atlas-NS-129 segregated as either a single dominant gene (3 Naked-tufted: 1 fuzzy) or as two dominant genes (9 Naked-tufted: 7 fuzzy). Three of the four F2 populations made with SC 9023-ns-57 segregated as either a single recessive gene (3 Fuzzy: 1 naked-tufted) or as duplicate recessive genes (9 Fuzzy: 7 naked-tufted). However, the F2 populations when crossed with the Fuzzy line of Tejas 48 showed a reversal of dominance. The F2 population of Atlas-NS-129 X Tejas 48 fit a 9 Fuzzy: 7 naked tufted ratio expected of two recessive genes. The F2 population of the cross of SC 9023-ns X Tejas 48 fit a 3 Naked-tufted: 1 fuzzy ratio expected of a single dominant gene. Additional studies will be necessary to fully determine the number of gene(s) and the expected phenotypic ratios of individual naked-tufted mutants in crosses with fuzzy seeded breeding lines. Eight of the F2 and F3 populations were also evaluated for lint yield, lint percent and AFIS fiber quality traits. The F2 and F3 populations of the cross of Atlas-NS-129 X Holland 338 produced the highest average lint yields (1089 kg ha−1) as well as excellent fiber quality. These data indicate that it may be possible to develop relatively high yielding naked tufted cultivars by crossing these mutant lines with elite higher yielding breeding lines.

INCREASING GENETIC DIVERSITY OF COTTON BREEDING PROGRAMS IN VENEZUELA

There is a steady increase of demands for textile crops, where cotton is the most popular natural fiber, therefore, it is necessary to exploit cotton genetic resources. In order to develop and improve crop populations, a cotton breeding program requires access to new sources of germplasm. With the objectives to evaluate the productivity of local and introduced genotypes from Syria and Brazil, and to expand the genetic base in the Venezuelan Cotton Breeding Program, 16 genotypes were evaluated at three locations in Venezuela during 2013 and 2014 using a randomized complete block design, with three replications. The traits evaluated were plant height, stem diameter, lint yield, boll weight, number of seed per boll, 100-seed weight, and fiber content. Highly significant differences (P≤0.01) were observed among genotypes, environments and their interaction for all traits, except for lint yield and number of seed per boll across environments. ʻC-2955-25ʼ showed high yield (3514.3 kg.ha-1) but was unstable across environments used in the evaluation. ʻL-2955-13ʼ was stable across the environments, suggesting that it would be a good parent. All the genotypes obtained values of lint percent above of 38%. The Syrians genotypes ʻAleppo-11ʼ and ʻAleppo-90ʼ showed high lint yield and good agronomic performance. Genotypes identified in this study could be used as potential sources of germplasm to be introduced in future breeding programs.

Equal potassium-nitrogen ratio regulated the nitrogen metabolism and yield of high-density late-planted cotton (Gossypium hirsutum L.) in Yangtze River valley of China

Potassium (K) plays a pivotal role in physiological and biochemical processes and is indispensable for efficient production of cotton. The optimal K fertilization ratio relative to reduced nitrogen (N) rate for efficient N metabolism and yield formation in late planted high-density cotton remain to be understood. In the field, three K ratios relative to N [K1 (K2O: N = 0.8: 1), K2 (K2O: N = 1: 1), and K3 (K2O: N = 1.2: 1)] were applied in a randomized complete block design, in 2016 and 2017. Results revealed that increasing the K fertilization ratio exerted a significant effect on leaf area, fresh and dry weight of functional leaf, chlorophyll content, and N metabolism, as well as yield and yield indices in both cropping years. Higher lint yield was obtained with the application of K2 and K3 rather than K1. Similarly, K2 and K3 treatments evidently improved the activity of N metabolizing enzymes such as NR (nitrate reductase), NiR (nitrite reductase), GS (glutamine synthetase), GOGAT (glutamate synthase), GPT (glutamic-pyruvic transaminase), and GOT (glutamic oxaloacetic transaminase). Moreover, leaf nitrogen, nitrate-N, free amino acids, and soluble protein contents were efficiently balanced in K2 and K3 treatments over K1. The findings of this study suggest that the application of K ratio must be equivalent to N to achieve an acceptable yield and profitable return in late-planted high-density cotton.

Registration of NM 970123, NM 990813, and NM W1218 Germplasm Lines of Upland Cotton

Three Acala cotton (Gossypium hirsutum L.) germplasm lines, designated as NM 970123 (Reg. No. GP‐1045, PI 688432) and NM 990813 (Reg. No. GP‐1046, PI 678373), both with the normal leaf, and NM W1218 (Reg. No. GP‐1047, PI 678372) with the okra leaf, were developed through pedigree selections by New Mexico State University to provide parental lines with improved yield potentials, lint percentage, or fiber quality. NM 970123 was derived from the hybridization of ‘Acala Prema’ by W5250, NM 990813 was derived from the cross of 87D3‐24/‘Acala 1517‐95’, and NM W1218 was derived from the hybridization of B4222 by H1014. The three lines were evaluated in four to eight replicated field tests in Las Cruces, NM. Compared with ‘Acala 1517‐99’, NM 970123 had consistently higher lint percentage (by 7.5%), with higher lint yield (by 6.3%); NM 990813 improved lint yield by 14.1%; and NM W1218 with the okra leaf outyielded the check by 5.9%. When evaluated in the Western Regional Variety Tests in 2001 to 2004, NM 970123 displayed significantly higher fiber strength and higher yarn tenacity, and it also had higher seed N content but significantly lower seed oil content.

Registration of Arkot 0611, Arkot 0617, and Arkot 0712 Cotton Germplasm Lines

Arkot 0611 (Reg. No. GP‐1035, PI 687864), Arkot 0617 (Reg. No. GP‐1037, PI 687866), and Arkot 0712 (Reg. No. GP‐1036, PI 687865) are conventional germplasm lines of cotton (Gossypium hirsutum L.) released by the Arkansas Agricultural Experiment Station (AAES) in April 2018. The lines were released as part of an ongoing effort to develop improved genotypes with enhanced yield, yield components, earliness, host plant resistance, and fiber properties. They share one common parent, DX25105N, a privately developed line made available to AAES by a Memorandum of Agreement. All three lines produced equal or higher lint yields than ‘DP 393’ and ‘UA48’ over 4 yr and at four test sites in Arkansas. Over all test sites, Arkot 0611 produced 10 and 22% higher lint yields than DP 393 and UA48, respectively. Both Arkot 0617 and Arkot 0712 produced 12% more lint than UA48. Lint percentage, seed per hectare, fibers per seed, and fiber density of each line were greater than UA48 and equal to or greater than DP 393. Compared with the check cultivars, all three lines were earlier maturing, but Arkot 0611 and Arkot 0617 tended to have taller plants. All three lines produced more dense leaf pubescence and bract trichomes than either check cultivar. Fiber quality of Arkot 0611 was inferior to either check, and fiber quality of Arkot 0617 and Arkot 0712 was higher than DP 393 but lower than UA48. The DX250105N parent of these lines increases the genetic diversity with the AAES cotton breeding program and broadens the available cotton germplasm pool.

GIZA 95” A LONG STAPLE EGYPTIAN COTTON VARIETY FOR MIDDLE AND UPPER EGYPT

Giza95 is a new long-staple Egyptian cotton variety. It has been introduced by the Cotton Breeding Research Section through artificial hybridization between the variety Giza80 and the genotype [(Giza83xGiza75) x5844] followed by the pedigree method of selection. The variety Giza 95 has 6.90% higher seed cotton yield (SCY) and 16.32% higher lint yield (LY) than the commercial variety Giza 90. It slightly surpassed Giza 90 for boll weight (BW) and lint percentage (L %). Fiber quality traits for the new variety Giza 95 was nearly

Registration of ‘UA114’ Cotton Cultivar

‘UA114’ (Reg. No. CV‐137, PI 685639) is a conventional cultivar of cotton (Gossypium hirsutum L.) released by the Arkansas Agricultural Experiment Station in April 2017. The cultivar was released as part of an ongoing effort to develop improved genotypes having enhanced yield, yield components, earliness, host plant resistance, and fiber properties. UA114 expressed earlier maturation than ‘DP 393’, which is considered a short‐season cultivar. Over Arkansas strain tests (four locations and 4 yr), UA114 produced 7.4 and 18.0% higher lint yield than DP 393 and ‘UA48’, respectively. UA114 is widely adapted and can produce high yields in contrasting environments. In the 2014 Regional Breeders Testing Network Test, UA114 produced lint yields equal to the highest‐yielding line (of 30 entries) at 10 of the 11 locations, as well as when evaluated over all locations. UA114 displays high resistance to bacterial blight and is similar to DP 393 in its response to most other diseases and to tarnished plant bug. Fiber quality of UA114 is similar to that of ‘UA222’. Its quality score value exceeded DP 393 but was lower than UA48. In most tests, UA114 produced longer fiber length, higher length uniformity, higher strength, and higher elongation than DP 393. UA114 displays an uncommon combination of high yielding ability, host plant resistance, early maturity, and high fiber quality.

Registration of Cotton Germplasm USDA MD 16‐1 and USDA MD 16‐2 with Enhanced Lint Yield and Fiber Quality

Upland cotton (Gossypium hirsutum L.) germplasm USDA MD 16‐1 (Reg. No. CV‐138, PI 682133), and USDA MD 16‐2 (Reg. No. CV‐139, PI 682134) have enhanced yield and good fiber quality. These germplasm lines were developed by the USDA‐ARS, Stoneville, MS, and released on 27 June 2017. Two crosses, MD 25‐51 × MD 10‐9‐1 and MD 25‐51 × MD 10‐9‐10 were made at the Jamie Whitten Delta State Research Center, USDA‐ARS, Stoneville, in 2010. The F1 population was grown at the winter nursery in Mexico in 2010. The F2 populations were planted at Stoneville in 2011. One boll per plant was bulked, and the F3 population was grown in 2012. This process was repeated during 2013 (F4). In 2014, individual plants (F5) were selected for progeny rows. In 2015 (F6) and 2016 (F7) selected progeny rows were tested for yield and fiber quality, and one progeny row from MD 25‐51 × MD 10‐9‐1 (named USDA MD 16‐1) and another progeny row from MD 25‐51 × MD 10‐9‐10 (named USDA MD 16‐2) were identified for their superior lint yield and fiber quality. During 2015 and 2016, the two germplasm were planted along with the check cultivars in randomized complete designs at Stoneville and were evaluated at the 2016 Regional Breeders’ Testing Network (RBTN) test across 13 locations spanning across all cotton growing regions. Data were collected on lint yield and quality parameters. Data at Stoneville indicated that both USDA MD 16‐1 and USDA MD 16‐2 had 9 to 16% and 6 to 14% higher lint yield than the two check cultivars, MD 25 and MD 10‐5, respectively In the 2016 RBTN across 13 locations, USDA MD 16‐1 was the top yielder (1710 kg ha−1), and USDA MD 16‐2 had the strongest fiber (355 kN m kg−1).

Registration of Arkot 0705 and Arkot 0711 Cotton Germplasm Lines

Arkot 0705 (Reg. No. GP‐1033, PI 685636) and Arkot 0711 (Reg. No. GP‐1034, PI 685637) are conventional germplasm lines of cotton (Gossypium hirsutum L.) released by the Arkansas Agricultural Experiment Station in April 2017. The lines were released as part of an ongoing effort to develop improved genotypes having enhanced yield, yield components, earliness, host plant resistance, and fiber properties. Both Arkot 0705 and Arkot 0711 produced equal or higher lint yields than ‘DP 393’ and ‘UA48’ over 4 yr and at four test sites in Arkansas. Over all test sites, Arkot 0705 and Arkot 0711 produced 10.7 and 12.0%, respectively, higher lint yields than DP 393, and both produced over 20% more lint than UA48. Arkot 0705 has less dense stem pubescence and bract trichomes, higher lint percentage, higher lint index, and more fibers per seed than DP 393. Arkot 0711 differs from DP 393 having more dense leaf pubescence, less dense stem pubescence, lower bract trichome density, being earlier maturing, and having higher lint percentage, lint index, fibers per seed, and fiber density. Both lines displayed high resistance to bacterial blight and were similar to DP 393 in their response to other diseases and tarnished plant bugs. Fiber quality of the two lines was slightly lower than DP 393 and considerably lower than UA48.

Combined effects of straw-derived biochar and bio-based polymer-coated urea on nitrogen use efficiency and cotton yield

ABSTRACTThe interactive effects of straw-derived biochar and bio-based polymer-coated urea (BPCU) was examined with a pot experiment conducted in 2014 and 2015. Using a split-plot design, the main plot factor was the form of straw use and the sub-plot factor was the type of N fertilizer. The soil inorganic nitrogen (N), organic carbon and lint yield of biochar treatments were significantly higher than for straw treatments. Meanwhile, the BPCU treatments enhanced nitrogen use efficiency (NUE) and yield over urea treatments. Biochar combined with BPCU resulted in the highest lint yield, 14.3–108.2% increasing over the other treatments, with NUE 27.1–63.5% increased. We attributed this superior performance to the interactive effects between BPCU’s controlled supply of N according to cotton’s N requirements and biochar’s functionalities in enhancing soil quality. Thus, the application of biochar and BPCU is a sustainable strategy to improve soil quality and increase cotton yield.

GENOTYPE-ENVIRONMENT INTERACTION IN YIELD OF HILL COTTON GENOTYPES

Stability analysis helps in understanding the adaptability of genotypes over different environmental conditions and the identification of adaptable genotypes. The experiment was conducted at the Chittagong Hill Tracts (CHT) areas of Bangladesh i.e. Bandarban, Rangamati and Khagrachari during May to September 2014 to study the genotype environment interaction effect on yield of some selected hill cotton genotypes. The experiment consisted of two factors: Factor A: Location (3 locations) - L1: Bandarban; L2: Rangamati and L3: Khagrachari; Factor B: Different cotton genotypes G1: HCG-4; G2: HCG-13, G3: HCG-15, G4: HCG-21, G5: HCG-26, G6: HCG-42, G7: HCG-51 and V8: HC-1 (Check). In case of location environment, the maximum boll per plant was recorded from Bandarban (19.13). The highest single boll weight was recorded from Bandarban (4.65 g). The highest seed cotton yield per hectare was recorded from Bandarban (1825 kg). The highest lint yield per hectare was recorded from Khagrachari (809 kg). For genotypes, maximum boll per plant (24.61), single boll weight (5.18 g), seed cotton yield per hectare (2170 kg) and lint yield per hectare (927 kg) was observed in HCG-13. In case of interaction of environments and genotypes, highest boll per plant (27.03), single ball weight (5.29 g), seed cotton yield per hectare (2170 kg), lint yield per hectare (981 kg) was observed in HCG-13 at Bandarban than the Rangamati and Khagrachari. Based on performance of eight genotypes HCG-13 followed by HCG-21 and HCG -42 was found to be highest yielder.Genotype HCG-13 was found highest yielder than the other genotypes and showed better performance at Bandarban than the Rangamati and Khagrachari.

Use of a managed stress environment in breeding cotton for a variable rainfall environment

Australian rainfed cotton is grown in regions with highly variable rainfall, with in-crop rainfall ranging from 100mm to 800mm. The CSIRO cotton breeding program conducts rainfed germplasm evaluations at its core research site, as well as a number of regional locations. As a direct result of our variable rainfall environment, yields <550kgha−1 are observed in 20% of years. Historically, these low yielding seasons result in variable experimental data with an increased risk of experimental failure as a non-significant result. Therefore, the aim of this research was twofold. Firstly, to develop and evaluate a managed stress environment (MSE) protocol where ‘rainfed’ germplasm evaluations are irrigated when yield is expected to fall below the minimum threshold for our target breeding environment (550kgha−1). Secondly, to assess the reliability of germplasm performance under rainfed conditions and limited water situations, clarifying whether germplasm selected under very dry rainfed conditions has the ability to produce high lint yield in seasons with higher than average rainfall. It was hypothesised that applying one furrow irrigation in very dry seasons will reduce within experiment variability and increase experimental yields to better reflect our breeding target environment. As irrigation timing will impact its efficacy, the OZCOT simulation model for cotton crop management was used to determine the most effective irrigation date with respect to soil water content and crop growth stage. The simulation, conducted with weather data from a 151year period, concluded that yields >550kgha−1 were not achieved in 27 seasons (18%). These 27 seasons underwent further simulations to determine the most suitable soil water content and crop growth stage where yield was increased with a single irrigation. It was determined that an irrigation should be applied to a ‘rainfed’ experiment if plant available water (PAW) reached approximately 40% by peak flowering (100-110 DAS). Paired rainfed and MSE experiments with 21 genotypes were established in 2013/14, 2014/15 and 2015/16 to provide field validation of the developed protocol. Genotype performance was assessed in terms of lint yield and fibre quality. Results show that in dry seasons (2013/14) irrigating the ‘rainfed’ treatment was necessary to reduce within experiment variability and increase yields above 550kgha−1. However, once rainfed yield levels increase due to greater in-crop rainfall (2014/15 and 2015/16), irrigation was no longer necessary. This was further supported by the result that genotype yield ranking differed between rainfed and MSE treatments. Genotype changes in fibre quality between treatments were small. It was concluded that a MSE, designed to produce experimental data better matched to our breeding target environment as well as reducing the risk of experimental failure, would be a worthwhile addition to rainfed evaluations conducted in variable rainfall environments.

Planting density and sowing date strongly influence growth and lint yield of cotton crops

This study assesses the effects of plant population density (PPD) and sowing date (SD) on growth, physiology and lint yield of a cotton crop. Seedling transplanting is one of the most dominant cotton production systems in China. But on the other hand, the net benefit is decreasing because the system is labor intensive. Therefore, a shorter cotton growing season is urgently needed to reduce the production costs through management practices such as adjusting sowing date and PPD. The following hypothesis was tested; would cotton yield and physiology from a late sowing be compensated by plant density? Field experiments were conducted with two sowing dates (S1, May 20; S2, June 04) as the main plot and three PPDs (D1, low; 7.5×104; D2, moderate; 9.0×104 and D3, high; 10.5×104ha−1) as the sub-plot. Early-sown plants produced 23%, 32%, 55%, 77% and 14%, taller stems more nodes, leaves and fruits, respectively, than the late-sown plants. Consequently, S1 produced 26% higher lint yield than S2. This increase in lint yield was mainly attributed to a relatively longer cropping season, which allowed utilization of available resources. Growth and fruit production in S1 plants were further increased by an increased photosynthetic rate (Pn) and N acquisition. Across the plant densities, 13% and 6% more lint yield was achieved under D2 than the D3 and D1, respectively. Moderate PPD increased lint yield by 13% and 6% over high and low, respectively. Nitrogen (N) acquisition was 45%, 33%, higher for S1 sown crop compared with S2, respectively. S1D2 had higher average (3.5VTkgha−1d−1) and maximum (4.5VMkgha−1d−1) rates of N accumulation in reproductive organs at the fastest accumulation point among other treatments. Our data suggest that for both sowing dates moderate PPD is a promising option, which allows light interception and penetration to the lower canopy, efficient N utilization and assimilate distribution to reproductive structures.

Genetic dissection of lint yield and fiber quality traits of G. hirsutum in G. barbadense background

Gossypium hirsutum L. is a widely cultivated species characterized by its high yield and wide environmental adaptability, while Gossypium barbadense is well known for its superior fiber quality. In the present report, we, for the first time, developed G. hirsutum chromosome segment introgression lines (ILs) in a G. barbadense background (GhILs_Gb) and genetically dissected the inheritance of lint yield and fiber quality of G. hirsutum in G. barbadense background. The GhILs_Gb contains introgressed segments spanning 4121.20 cM, which represents 82.20% of the tetraploid cotton genome, with an average length of 18.65 cM. A total of 39 quantitative trait loci (QTLs) for six traits are identified in this IL population planted in Xinjiang. Four QTL clusters are detected. Of them, however, three clusters have deleterious effects on fiber length and strength and boll weight, and only one cluster on Chr. D9 can be used in marker-assisted selection (MAS) to increase lint percentage and decrease micronaire value in G. barbadense. QTL mapping showed that most of yield-related QTLs detected have positive effects and increase lint yield in G. barbadense, while most of fiber quality-related QTLs have deleterious effects except for micronaire. It suggested that G. hirsutum evolved to have a high lint yield. Several lines improved in lint percentage and boll size in G. barbadense by introgressed one fragment of G. hirsutum have been developed from the GhILs_Gb. The ILs developed, and the analyses presented here will enhance the understanding of the genetics of lint yield and fiber quality in G. hirsutum and facilitate further molecular breeding to improve lint yield in G. barbadense.

Field assessment of commercial cotton cultivars for Verticillium wilt resistance and yield

Verticillium wilt is responsible for substantial yield losses in cotton. The use of cultivars with partial resistance to Verticillium wilt is a preferred management strategy. Cotton breeders utilize rating scales based on severity of foliar symptom expression and/or defoliation when making cultivar selections. The objective of this research was to determine the yield relationship with cultivars grouped by both incidence of Verticillium wilt during the boll filling stage, and late season defoliation in fields with a history of Verticillium wilt. Small plot, replicated cultivar trials were conducted over an 11 year period in west Texas. Cultivars were divided into four classes (A–D) based on normalized wilt incidence (NW) and four classes based on normalized defoliation ratings (ND). Classes were determined through a mixed model analysis of cultivars, with T-test comparisons between a partially resistant check (Fibermax 2484B2F) and a susceptible check (Deltapine 0912B2RF). The A and C classes did not differ (P = 0.05) from the partially resistant and susceptible checks, respectively. Classes were used in a mixed model analysis with lint yield. In a model with only NW classes, lint yield decreased significantly as NW increased with least square mean values of 1421, 1385, 1284 and 1204 kg/ha, for classes A, B, C and D, respectively. In a model with both NW and ND classes, the A/A class combination of NW and ND had a significantly (P ≤ 0.05) higher lint yield (1776 kg/ha) than any other combination. NW/ND class combinations of A/B, B/A, B/B, and C/A had intermediate yields, and ND classes of C or D had the lowest yields. Cultivars with both low wilt and defoliation incidences should result in higher yields in fields infested with Verticillium dahliae. Furthermore, these two rating criteria could be used to standardize the process for developing resistant cultivars.

Growth and yield responses of cotton (Gossypium hirsutum) to inorganic and organic fertilizers in southern Malawi

Fertilizer trees, the nitrogen-fixing legumes, such as gliricidia (Gliricidia sepium) and tephrosia (Tephrosia spp.) have been used to improve soil fertility for higher crop yields in nitrogen deficient soils. Many studies have focused on how these fertilizer trees improve maize yield, but there has been a dearth of information on the effect of fertilizer tree species on cotton growth and yield. A study was undertaken for two cropping seasons (2012/13 and 2013/14) with the objective of assessing IRM 81 cotton growth and yield responses to tephrosia and/or gliricidia biomass with or without inorganic fertilizer application. Boll opening significantly varied (P < 0.0001) with treatments and early boll opening was observed in plots where only inorganic fertilizer was applied. Higher lint yield (mean of 1397 kg/ha) was obtained in the second cropping season than in the first cropping season (480 kg/ha) and the application of gliricidia biomass with fertilizer gave the highest lint yield (2121 kg/ha). The lowest lint and seed yields were obtained from plots where tephrosia biomass only was applied. It is concluded that the use of gliricidia biomass with inorganic fertilizer improved cotton yields. The high amount of gliricidia biomass (due to prolific coppicing) applied contributed to higher cotton lint yields with reduced rates of inorganic fertilizer application, making gliricidia-cotton intercropping a cost-effective option to smallholder farmers.

Registration of Arkot 0305, Arkot 0306, Arkot 0309, and Arkot 0316 Germplasm Lines of Cotton

Arkansas Agricultural Experiment Station has released four germplasm lines of Upland cotton, Gossypium hirsutum L., designated as Arkot 0305 (Reg. No. GP-983, PI 669971), Arkot 0306 (Reg. No. GP-984, PI 671966), Arkot 0309 (Reg. No. GP-981, PI 669969), and Arkot 0316 (Reg. No. GP-982, PI 669970). Arkot 0305, Arkot 0306, and Arkot 0316 were derived from crosses with one common parent, Arkot 9203-17. The second parent for Arkot 0305, Arkot 0306, and Arkot 0316 was ‘DP 491’, DPX99X35, and Arkot 9111, respectively. Arkot 0309 was derived from a cross of DP 491 and ‘FM 966’. All four lines exhibited high fiber density and produced equal or higher lint yields than ‘DP 393’ over 4 yr and four test sites in Arkansas. Arkot 0305, Arkot 0306, and Arkot 0316 produced higher yields than Arkot 0309. Basic yield components (lint index and seed per area) of Arkot 0305, Arkot 0309, and Arkot 0316 were similar to DP 393, while Arkot 0306 produced yield with lower lint index and higher seed per area. The lines differed with respect to lint fraction, plant height, maturity, and relative trichome density on leaves, stems, and bracts. All four lines displayed resistance to bacterial blight [caused by Xanthomonas axonopodis pv. malacearum (Smith) Dye] and Fusarium wilt [caused by Fusarium oxysporum Schlect. F. sp. vasinfectum (Atk.) Snyd. & Hans.]. Arkot 0305 and Arkot 0306 displayed resistance to tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), equal to DP 393, but higher than Arkot 0309 and Arkot 0316. Fiber quality of Arkot 0309 was superior to the other three Arkot lines and DP 393. Each line displayed high yielding ability, favorable yield components, specific host plant resistance traits, early maturity and acceptable-to-superior fiber quality.