Brown Cotton Fibers Research Articles

Integrative Transcriptomic and Metabolic Analyses Reveal That Flavonoid Biosynthesis Is the Key Pathway Regulating Pigment Deposition in Naturally Brown Cotton Fibers.

Brown cotton is a major cultivar of naturally colored cotton, and brown cotton fibers (BCFs) are widely utilized as raw materials for textile industry production due to their advantages of being green and dyeing-pollution-free. However, the mechanisms underlying the pigmentation in fibers are still poorly understood, which significantly limits their extensive applications in related fields. In this study, we conducted a multidimensional comparative analysis of the transcriptomes and metabolomes between brown and white fibers at different developmental periods to identify the key genes and pathways regulating the pigment deposition. The transcriptomic results indicated that the pathways of flavonoid biosynthesis and phenylpropanoid biosynthesis were significantly enriched regulatory pathways, especially in the late development periods of fiber pigmentation; furthermore, the genes distributed in the pathways of PAL, CHS, F3H, DFR, ANR, and UFGT were identified as significantly up-regulated genes. The metabolic results showed that six metabolites, namely (-)-Epigallocatechin, Apiin, Cyanidin-3-O-glucoside, Gallocatechin, Myricetin, and Poncirin, were significantly accumulated in brown fibers but not in white fibers. Integrative analysis of the transcriptomic and metabolomic data demonstrated a possible regulatory network potentially regulating the pigment deposition, in which three MYB transcription factors promote the expression levels of flavonoid biosynthesis genes, thereby inducing the content increase in (-)-Epigallocatechin, Cyanidin-3-O-glucoside, Gallocatechin, and Myricetin in BCFs. Our findings provide new insights into the pigment deposition mechanism in BCFs and offer references for genetic engineering and breeding of colored cotton materials.

Naturally colored cotton for wearable applications.

Naturally colored cotton (NCC) offers an environmentally friendly fiber for textile applications. Processing white cotton fiber into textiles requires extensive energy, water, and chemicals, whereas processing of NCC skips the most polluting activity, scouring-bleaching and dyeing; therefore, NCC provides an avenue to minimize the harmful impacts of textile production. NCC varieties are suitable for organic agriculture since they are naturally insect and disease-resistant, salt and drought-tolerant. Various fiber shades, ranging from light green to tan and brown, are available in the cultivated NCC (Gossypium hirsutum L.) species. The pigments responsible for the color of brown cotton fiber are proanthocyanidins or their derivatives synthesized by the flavonoid pathway. Due to pigments, the NCC has excellent ultraviolet protection properties. Some brown cotton varieties exhibited superior thermal resistance of fiber that can be used to make fabrics with enhanced flame retardancy. Here, we review molecular mechanisms involved in the pigment production of brown cotton and challenges in breeding NCC varieties with a wide range of colors but without penalty in fiber quality. Also, we discuss opportunities for NCC with flame-retarding properties in textile applications.

Multi-omics analysis of pigmentation related to proanthocyanidin biosynthesis in brown cotton (Gossypium hirsutum L.).

Naturally-colored brown cotton (NBC) fiber is an environmentally friendly raw source of fiber for textile applications. The fiber of some NBC cultivars exhibits flame-retardant properties, which can be used in textiles that require flame resistance. Proanthocyanidins or their derivatives are responsible for the brown pigment in NBC; however, how flame retardancy is related to pigmentation in NBC is poorly understood. To gain insight into brown pigment biosynthesis, we conducted comparative transcripts and metabolites profiling analysis of developing cotton fibers between the brown (MC-BL) and white (MC-WL) cotton near-isogenic lines (NILs), genetically different only in the Lc1 locus. In this study, mass spectrometry was used to detect metabolites in BL and WL developing fibers at 8, 12, 16, 20, 24, 36, and 40 days post anthesis (DPA) and mature fibers. Transcripts analysis was performed at two critical fiber developmental points, 8 DPA (fiber elongation) and 20 DPA (secondary cell wall deposition). We found 5836 (ESI MS positive mode) and 4541 (ESI MS negative mode) metabolites significantly different accumulated between BL and WL. Among them, 142 were known non-redundant metabolites, including organic acids, amino acids, and derivatives of the phenylpropanoid pathway. Transcript analysis determined 1691 (8 DPA) and 5073 (20 DPA) differentially expressed genes (DEGs) between BL and WL, with the majority of DEGs down-regulated at 20 DPA. Organic acids of the citric acid cycle were induced, while most of the detected amino acids were reduced in the MC-BL line. Both cis- and trans-stereoisomers of flavan-3-ols were detected in developing MC-WL and MC-BL fibers; however, the gallocatechin and catechin accumulated multiple times higher. Gas chromatography-mass spectrometry (GC-MS) analysis of fatty acids determined that palmitic acid long-chain alcohols were the main constituents of waxes of mature fibers. Energy-dispersive X-ray spectrometry (EDS) analysis of mature fibers revealed that potassium accumulated three times greater in MC-BL than in MC-WL mature fibers. This study provides novel insights into the biosynthesis of pigments and its association with flame retardancy in NBC fibers.

Cloning and functional analysis of GhDFR1, a key gene of flavonoid synthesis pathway in naturally colored cotton.

The naturally colored brown cotton fiber is the most widely used environmentally friendly textile material, which primarily contains proanthocyanidins and their derivatives. Many structural genes in the flavonoid synthesis pathway are known to improve the genetic resources of naturally colored cotton. Among them, DFR is a crucial late enzyme to synthesis both anthocyanins and proanthocyanidins in the plant flavonoid pathway. The protein sequences of GhDFRs were analyzed using bioinformatic tools. The expression levels of GhDFRs in various tissues and organs of upland cotton Zongxu1 (ZX1), were analyzed by quantitative real-time PCR, and the expression pattern of GhDFR1 during fiber development of white cotton and brown cotton was analyzed further. The function of GhDFR1 in NCC ZX1 was preliminarily analyzed by virus induced gene silencing (VIGS) technology. Bioinformatic analysis revealed that GhDFRs sequences in upland cotton genome were extremely conserved. Furthermore, evolutionary tree analysis revealed that the functions of GhDFR1 and GhDFR2, and GhDFR3 and GhDFR4, presented different and shared some similarities. Our study showed GhDFR1 and GhDFR2 were specifically expressed in fibers, while GhDFR3 and GhDFR4 were specifically expressed in petals. GhDFR1 was exclusively expressed in brown cotton fiber at various stages of development and progressively increased with the growth of fiber, but the trend of expression in white cotton was quite the opposite. We silenced GhDFR1 expression in brown cotton fiber using VIGS technology, and observed the VIGS-interference plants. After reducing the expression level of GhDFR1, the period for significant GhDFR1 expression in the developing fibers changed, reducing the content of anthocyanins, and lightening the color of mature cotton fibers. GhDFR1 was preferentially expressed in brown cotton during fiber development. The timing of GhDFR1 expression for flavonoid synthesis altered, resulting in anthocyanin contents reduced and the fiber color of the GhDFR1i lines lightened. These findings showed the role of GhDFR1 in fiber coloration of NCC and provided a new candidate for NCC genetic improvement.

Transcriptome and proteome profiling revealed the key genes and pathways involved in the fiber quality formation in brown cotton

Colored cotton is also called eco-cotton because of its natural color fiber. It is inferior in yield and quality than white cotton. The underlying regulatory genes involved in fiber quality and pigment synthesis are not well understood. This study aimed to investigate the transcriptomic and proteomic changes during fiber development in a brown cotton cultivar (Z161) and a white cotton cultivar. The differential proteins with the same expression trend as genes were significantly and positively correlated with corresponding fold changes in expression. Enrichment analysis revealed that Z161, enriched in fiber elongation genes related to flavonoid biosynthesis, phenylalanine metabolism, glutathione metabolism, and many more genes (proteins) are up-regulated. Moreover, 164 glycosyltransferases genes, 15 MYB-bHLH-WD40 genes, and other transcription factors such as C2H2 (12), ERF (11), and NAC (7) were preferentially expressed in Z161. Weighted correlation network analysis identified fatty acid synthesis and energy metabolism as the principal metabolic pathways in both cotton genotypes during fiber development. Identified 15 hub genes will provide important insights for genetic manipulation of fiber quality and pigment deposition balance in brown cotton fibers.

Transcriptome and Metabolome Profiling Unveil Pigment Formation Variations in Brown Cotton Lines (Gossypium hirsutum L.)

Naturally brown colored cotton (NBCC) is becoming increasingly popular due to its natural properties of coloration. However, poor fiber quality and color fading are key issues that are hindering the cultivation of naturally colored cotton. In this study, based on transcriptome and metabolome of 18 days post-anthesis (DPA), we compared the variations of pigment formation in two brown cotton fibers (DCF and LCF), with white cotton fiber (WCF) belonging to a near-isogenic line. A transcriptome study revealed a total of 15,785 differentially expressed genes significantly enriched in the flavonoid biosynthesis pathway. Furthermore, for flavonoid biosynthesis-related genes, such as flavonoid 3'5'-hydroxylase (F3'5'H), anthocyanidin synthase (ANS), anthocyanidin reductase (ANR), chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR), and chalcone isomerase (CHI), their expressions significantly increased in LCF compared with DCF and WCF. Moreover, transcription factors MYB and bHLH were significantly expressed in LCF and DCF. Most flavonoid-related metabolites (myricetin naringenin, catechin, epicatechin-epiafzelechin, and epigallocatechin) were found to be more highly up-regulated in LCF and DCF than WCF. These findings reveal the regulatory mechanism controlling different brown pigmentation in cotton fibers and elucidate the need for the proper selection of high-quality brown cotton fiber breeding lines for promising fiber quality and durable brown color pigmentation.

Identification and Functional Analysis of the Promoter of a Leucoanthocyanidin Reductase Gene from Gossypium hirsutum.

Leucoanthocyanidin reductase (LAR) is the critical enzyme in the synthesis pathway of proanthocyanidins, which are the primary pigments in brown cotton fibers. Our previous study has revealed significant differences in the expression levels of GhLAR1 between white and brown cotton fibers at 10 DPA. In this work, the expression pattern of the GhLAR1 gene was further studied, and the promoter of GhLAR1 (1780bp) was isolated and characterized. Bioinformatic analysis indicated that GhLAR1 promoter contained many known light response elements and several defenses related to transcriptional factor-binding boxes, which may partially explain the response of the GhLAR1 to temperature, NaCl, and PEG treatments. Furthermore, GhLAR1 was preferentially and strongly expressed in fibers and flowers of cotton, and the expression levels in all tested tissues (especially fibers) of brown cotton were significantly higher than those in white cotton. Consistent with the expression analysis, the GhLAR1 promoter mainly drove GUS expression in epidermal trichomes and floral organs.

Transcriptome Co-expression Network and Metabolome Analysis Identifies Key Genes and Regulators of Proanthocyanidins Biosynthesis in Brown Cotton.

Brown cotton fiber (BCF) is a unique raw material of naturally colored cotton (NCC). But characteristics of the regulatory gene network and metabolic components related to the proanthocyanidins biosynthesis pathway at various stages of its fiber development remain unclear. Here, the dynamic changes in proanthocyanidins biosynthesis components and transcripts in the BCF variety “Zong 1-61” and its white near-isogenic lines (NILs) “RT” were characterized at five fiber developmental stages (0, 5, 10, 15, and 20 days post-anthesis; DPA). Enrichment analysis of differentially expressed genes (DEGs), comparison of metabolome differences, and pathway enrichment analysis of a weighted gene correlation network analysis together revealed the dominant gene expression of flavonoid biosynthesis (FB), phenylpropanoid metabolisms, and some carbohydrate metabolisms at 15 or 20 DPA than white cotton. Eventually, 63 genes were identified from five modules putatively related to FB. Three R2R3-MYB and two bHLH transcription factors were predicted as the core genes. Further, GhANS, GhANR1, and GhUFGT2 were preliminarily regulated by GhMYB46, GhMYB6, and GhMYB3, respectively, according to yeast one-hybrid assays in vitro. Our findings provide an important transcriptional regulatory network of proanthocyanidins biosynthesis pathway and dynamic flavonoid metabolism profiles.

Thermosensitive textiles made from silver nanoparticle-filled brown cotton fibers.

Filling fibers with nanomaterials can create new functions or modify the existing properties. However, as nanocomposite formation for natural cellulosic fibers has been challenging, little information is available on how the embedded nanomaterials alter the properties of cellulosic fibers. Here we filled brown cotton fibers with silver nanoparticles (Ag NPs) to examine their thermosensitive properties. Using naturally present tannins in brown cotton fibers as a reducing agent, Ag NP-filled brown cotton fibers (nanoparticle diameter of about 28 nm, weight fraction of 12 500 mg kg−1) were produced through a one-step process without using any external agents. The in situ formation of Ag NPs was uniform across the nonwoven cotton fabric and was concentrated in the lumen of the fibers. The insertion of Ag NPs into the fibers shifted the thermal decomposition of cellulose to lower temperatures with increased activation energy and promoted heat release during combustion. Ag NPs lowered the thermal effusivity of the fabric, causing the fabric to feel warmer than the control brown cotton. Ag NP-filled brown cotton was more effectively heated to higher temperatures than control brown cotton under the same heating treatments.

Brown Cotton Fibers Self-Produce Ag Nanoparticles for Regenerating Their Antimicrobial Surfaces

To produce textiles that regenerate antimicrobial surfaces wash after wash, we synthesized and immobilized antimicrobial silver nanoparticles (Ag NPs) within brown cotton fibers. This composite for...

Genome-wide identification of ABCC gene family and their expression analysis in pigment deposition of fiber in brown cotton (Gossypium hirsutum).

ABC (ATP-binding cassette) transporters are a class of superfamily transmembrane proteins that are commonly observed in natural organisms. The ABCC (ATP-binding cassette C subfamily) protein belongs to a subfamily of the ABC protein family and is a multidrug resistance-associated transporter that localizes to the tonoplast and plays a significant role in pathogenic microbial responses, heavy metal regulation, secondary metabolite transport, and plant growth. Recent studies have shown that the ABCC protein is also involved in the transport of anthocyanins/proanthocyanidins (PAs). To clarify the types and numbers of ABCC genes involved in PA transport in Gossypium hirsutum, the phylogenetic evolution, physical location, and structure of ABCC genes were classified by bioinformatic methods in the upland cotton genome, and the expression levels of these genes were analyzed at different developmental stages of the cotton fiber. The results showed that 42 ABCC genes were initially identified in the whole genome of upland cotton; they were designated GhABCC1-42. The gene structure and phylogenetic analysis showed that the closely related ABCC genes were structurally identical. The analysis of chromosomal localization demonstrated that there were no ABCC genes on the chromosomes of AD/At2, AD/At5, AD/At6, AD/At10, AD/At12, AD/At13, AD/Dt2, AD/Dt6, AD/Dt10, and AD/Dt13. Outside the genes, there were ABCC genes on other chromosomes, and gene clusters appeared on the two chromosomes AD/At11 and AD/Dt8. Phylogenetic tree analysis showed that some ABCC proteins in G. hirsutum were clustered with those of Arabidopsis thaliana, Vitis vinifera and Zea mays, which are known to function in anthocyanin/PA transport. The protein structure prediction indicated that the GhABCC protein structure is similar to the AtABCC protein in A. thaliana, and most of these proteins have a transmembrane domain. At the same time, a quantitative RT-PCR analysis of 42 ABCC genes at different developmental stages of brown cotton fiber showed that the relative expression levels of GhABCC24, GhABCC27, GhABCC28, GhABCC29 and GhABCC33 were consistent with the trend of PA accumulation, which may play a role in PA transport. These results provide a theoretical basis for further analysis of the function of the cotton ABCC genes and their role in the transport of PA.

Flavonoid biosynthetic and starch and sucrose metabolic pathways are involved in the pigmentation of naturally brown-colored cotton fibers

The pigment of naturally brown-colored Upland cotton fibers is caused by condensed tannin formed by the oxidation of proanthocyanidins (PAs). However, the specific roles of PA biosynthesis and glucose metabolism in brown pigmentation during fiber development are unclear. Here, proteomes and metabolomes of ovules collected at 0 days post anthesis (DPA) and fibers collected at 10, 20, and 30 DPA from the brown-colored cotton ‘Zong 1-61’ (Z161) and white-colored cotton ‘RT’ were integrated. Compared with in RT, the proteins in the flavonoid biosynthetic pathway of Z161 were highly accumulated at 10 DPA and 20 DPA. The metabolome data showed that epi-flavan-3-ols were the major components in the brown fibers of Z161 from 10 to 30 DPA. Significantly lower levels of the catalytic enzymes of the starch and sucrose metabolic pathway, which affects cellulose biosynthesis, were found in Z161 compared with in RT, except endoglucanase and uridine-5′-diphosphate (UDP)-d-glucose pyrophosphorylase. However, the UDP-d-glucose content was significantly higher in Z161 than in RT because UDP-d-glucose pyrophosphorylase catalyzes the formation of glucose-1-phosphate, rather than sucrose, and it may be a precursor for brown cotton fiber pigment biosynthesis and glycosylation. The final biosynthetic pathway involved in the formation of brown cotton fiber pigmentation is the generation of PAs, which then form condensed tannins through the actions of a condensation enzyme and polyphenol oxidase, rather than the anthocyanin pathway. These findings provide insights into the roles of glucose metabolism in the development of brown cotton fibers and the mechanisms underlying their pigmentation.

Phenylpropanoid metabolism and pigmentation show divergent patterns between brown color and green color cottons as revealed by metabolic and gene expression analyses

BackgroundNaturally-colored cotton has become increasingly popular because of their natural properties of coloration, UV protection, flame retardant, antibacterial activity and mildew resistance. But poor fiber quality and limited color choices are two key issues that have restricted the cultivation of naturally-colored cotton. To identify the possible pathways participating in fiber pigmentation in naturally-colored cottons, five colored cotton accessions in three different color types (with green, brown and white fiber) were chosen for a comprehensive analysis of phenylpropanoid metabolism during fiber development.ResultsThe expression levels of flavonoid biosynthesis pathway genes in brown cotton fibers were significantly higher than those in white and green cotton fibers. Total flavonoids and proanthocyanidin were higher in brown cotton fibers relative to those in white and green cotton fibers, which suggested that the flavonoid biosynthesis pathway might not participate in the pigmentation of green cotton fibers. Further expression analysis indicated that the genes encoding enzymes for the synthesis of caffeic acid derivatives, lignin and lignan were activated in the developing fibers of the green cotton at 10 and 15 days post-anthesis.ConclusionsOur results strengthen the understanding of phenylpropanoid metabolism and pigmentation in green and brown cotton fibers, and may improve the breeding of naturally-colored cottons.

Qualitative analysis of cotton fiber pigment composition

Naturally colored cotton is a green textile material. To cultivate new colored cotton and improve its performance, we must first understand the types, composition, and formation mechanism of the pigments in colored cotton. This study aims to explore the composition and structure of cotton fiber pigments. Qualitative analyses of pigment extracts from brown cotton, green cotton, and white cotton fibers were carried out using ultraviolet spectroscopy, diagnostic agents, and liquid chromatography–mass spectrometry. The main component of cotton fiber pigments was flavonoids, and specific types of flavonoids were found in the pigments in brown cotton, green cotton, and white cotton fibers. Research on the composition of cotton fiber pigments can increase our understanding of colored cotton fibers and lay a foundation for the cultivation, planting, and development of colored cotton fibers, as well the identification of naturally colored cotton from dyed cotton.

Thermal properties and surface chemistry of cotton varieties mineralized with calcium carbonate polymorphs by cyclic dipping.

In this study, hydroentangled cotton nonwovens were identified as effective hosts for mineralization of calcium carbonate (CaCO3) polymorphs to modify and improve their properties. All cotton varieties studied, including raw white cotton, scoured white cotton, and raw brown cotton, readily crystallized CaCO3via a simple cyclic dipping process. A combination of analyses agreed that the surface chemistry of cotton fibers influenced the formation of different CaCO3 polymorphs. Scoured white cotton that consisted of almost pure cellulose predominantly produced the most stable calcite, whereas raw white and raw brown cottons that contain proteins facilitated the production of partial metastable vaterite. The morphology of calcite was better defined on the scoured cotton. The mineralization altered the hydrophobic surface of raw cottons to be hydrophilic, i.e., two-fold increase in moisture regain and decrease in water contact angle from 130 to 0 degrees. The mineralized cottons also exhibited improved thermal resistance, i.e., slower thermal decomposition with decreased activation energies and reduction in heat release capacity by up to 40%.

Zinc Finger-Homeodomain Transcriptional Factors (ZHDs) in Upland Cotton (Gossypium hirsutum): Genome-Wide Identification and Expression Analysis in Fiber Development.

Zinc finger-homeodomain (ZHD) genes encode a family of plant-specific transcription factors that not only participate in the regulation of plant growth and development but also play an important role in the response to abiotic stress. The ZHD gene family has been studied in several model plants, including Solanum lycopersicum, Zea mays, Oryza sativa, and Arabidopsis thaliana. However, a comprehensive study of the genes of the ZHD family and their roles in fiber development and pigmentation in upland cotton has not been completed. To address this gap, we selected a brown fiber cultivar for our study; brown color in cotton is one of the most desired colors in the textile industry. The natural colored fibers require less processing and little dying, thereby eliminating dye costs and chemical residues. Using bioinformatics approaches, we identified 37 GhZHD genes from Gossypium hirsutum and then divided these genes into seven groups based on their phylogeny. The GhZHD genes were mostly conserved in each subfamily with minor variations in motif distribution and gene structure. These genes were largely distributed on 19 of the 26 upland cotton chromosomes. Among the Gossypium genomes, the paralogs and orthologs of the GhZHD genes were identified and further characterized. Furthermore, among the paralogs, we observed that the ZHD family duplications in Gossypium genomes (G. hirsutum, G. arboreum, and G. raimondii) were probably derived from segmental duplication or genome-wide duplication (GWD) events. Through a combination of qRT-PCR and proanthocyanidins (PA) accumulation analyses in brown cotton fibers, we concluded that the candidate genes involved in early fiber development and fiber pigment synthesis include the following: GhZHD29, GhZHD35, GhZHD30, GhZHD31, GhZHD11, GhZHD27, GhZHD18, GhZHD15, GhZHD16, GhZHD22, GhZHD6, GhZHD33, GhZHD13, GhZHD5, and GhZHD23. This study delivers insights into the evolution of the GhZHD genes in brown cotton, serves as a valuable resource for further studies, and identifies the conditions necessary for improving the quality of brown cotton fiber.

Comparative genomic analysis of the PKS genes in five species and expression analysis in upland cotton.

Plant type III polyketide synthase (PKS) can catalyse the formation of a series of secondary metabolites with different structures and different biological functions; the enzyme plays an important role in plant growth, development and resistance to stress. At present, the PKS gene has been identified and studied in a variety of plants. Here, we identified 11 PKS genes from upland cotton (Gossypium hirsutum) and compared them with 41 PKS genes in Populus tremula, Vitis vinifera, Malus domestica and Arabidopsis thaliana. According to the phylogenetic tree, a total of 52 PKS genes can be divided into four subfamilies (I–IV). The analysis of gene structures and conserved motifs revealed that most of the PKS genes were composed of two exons and one intron and there are two characteristic conserved domains (Chal_sti_synt_N and Chal_sti_synt_C) of the PKS gene family. In our study of the five species, gene duplication was found in addition to Arabidopsis thaliana and we determined that purifying selection has been of great significance in maintaining the function of PKS gene family. From qRT-PCR analysis and a combination of the role of the accumulation of proanthocyanidins (PAs) in brown cotton fibers, we concluded that five PKS genes are candidate genes involved in brown cotton fiber pigment synthesis. These results are important for the further study of brown cotton PKS genes. It not only reveals the relationship between PKS gene family and pigment in brown cotton, but also creates conditions for improving the quality of brown cotton fiber.

High resistance to thermal decomposition in brown cotton is linked to tannins and sodium content

Brown cotton fibers (SA-1 and MC-BL) studied were inferior to a white cotton fiber (Sure-Grow 747) in fiber quality, i.e., a shorter length, fewer twists, and lower crystallinity, but showed superior thermal resistance in thermogravimetric, differential thermogravimetric, and microscale combustion calorimetric (MCC) analyses. Brown cotton fibers yielded 11–23 % smaller total heat release and 20–40 % greater char. Washing fibers in water and a 1 % NaOH solution showed that rich natural inorganic components and the condensed tannins present in brown cotton are responsible for the unusual thermal property. The loss of inorganics from white cotton during a water wash increased the thermal decomposition temperature of cellulose, resulting in no char yield. However, the stronger binding of metal ions for brown cotton as well as its dominant adsorption of sodium ions after a 1 % NaOH wash facilitated the low-temperature thermal-reaction route; the sodium content showed a significant negative correlation with the heat release capacity of the fiber. Condensed tannins greatly enhanced the adsorption of sodium ions to the fiber and exhibited inherent thermal stability. The limiting oxygen indices (LOI) calculated from the MCC parameters indicated the slower burning characteristic of brown cotton, and its LOI was further increased upon adsorption of sodium ions.

Estabilidade e adaptabilidade de genótipos de algodão de fibra colorida quanto aos caracteres de fibra

O objetivo deste trabalho foi verificar a presença de interação genótipo x ambiente (G x A) e determinar a adaptabilidade e estabilidade fenotípica de linhagens de algodão de fibra marrom, utilizando o modelo de Ebehart & Russell. Foram conduzidos sete experimentos nos estados de CE, GO, MS e RN, em 2010 e 2011, em regime irrigado e de sequeiro. O delineamento utilizado foi blocos casualizados com quatro repetições. Foram avaliados 11 genótipos, segundo sete caracteres relativos à fibra. A interação G x A foi significativa para a maioria dos caracteres. As linhagens 1, 2, 3, 4, 5 e 7 demonstraram capacidade de resposta à melhoria de ambiente, sendo 1 e 5 os genótipos que apresentaram comportamento previsível para todas as características. O índice de fibras curtas mostrou ser uma característica de alta previsibilidade

Physical and combustion properties of nonwoven fabrics produced from conventional and naturally colored cottons

A comparative study was conducted to identify the effects of processing on physical and combustion properties of needlepunched (NP) and hydroentangled (H-E) nonwoven fabrics produced from fibers of white fiber cotton and a naturally colored brown fiber cotton. A significantly higher degree of flame retardancy (FR) in was observed in fabrics produced from brown cotton fibers compared with white fibers. Calorimetry revealed lower heat release capacity, lower peak heat release rate, and total heat release from brown fibers compared with white fibers. The ash content was also higher in brown fiber samples suggesting higher levels of inorganic elements in the brown fibers. Elemental analyses revealed brown cotton fibers had higher levels of known FR elements including phosphorous and magnesium. The H-E process reduced FR in brown fabrics, which also correlated with a reduction in phosphorous. However, brown H-E fabrics still maintained higher FR than white H-E fabrics. Water content analysis indicated higher water levels in brown fibers, particularly brown greige fibers, which correlated with increased FR. Processing parameters such as energy of H-E did not affect combustion of the two fabric types. Scouring of the brown fiber fabrics reduced, but did not remove coloration, while scouring and bleaching removed the brown color completely. Scouring alone, or scouring and bleaching, completely removed the higher FR properties of the brown fiber fabrics. The results indicate that the mechanism of FR in brown cotton fibers is dependent on multiple compositional factors that may include element content, water content, and compounds related to coloration.