Abstract Cotton is an essential worldwide commodity, and Brazil ranks fourth in world production and second in export. The present work aimed to gather the genealogies and estimate the genetic base of 109 Brazilian cotton cultivars released from 1932 to 2021. Twelve of the 68 ancestors identified contributed with 52.03% of the genes, and 33% of the cultivars resulted from the direct selection from landraces or old cultivars, evidencing a narrow genetic base. Over time, especially after 1990, the increases in the number of cultivars released and number of ancestors added to the breeding programs were driven by the need to reduce the cultivars' cycle for coexistence with pests and to make them suitable for mechanized cultivation in the new agricultural frontiers. However, Brazilian cotton cultivars still have a narrow genetic base, with the important participation of the ancestors CNPA SRI3, CKR 100W, C-77 and Express.

RESUMO: Compreender a diversidade genética e contornar os problemas causados pela interação genótipos por ambientes é uma etapa importante em programas de melhoramento. Este estudo teve como objetivo estimar a diversidade genética e aplicar a metodologia de biplot genótipo + genótipo por ambiente (GGE biplot) em doze genótipos de algodão avaliados quanto ao rendimento da fibra, comprimento da fibra, resistência da fibra e micronaire. A estimativa dos componentes de variância e dos parâmetros genéticos foi feita através do método da máxima verossimilhança restrita e a predição dos valores genotípicos por meio da melhor predição linear não enviesada. Os métodos de Tocher modificado e análise de componentes principais (PCA) foram utilizados para quantificar a diversidade genética entre os genótipos. O método GGE biplot foi conduzido para encontrar os melhores genótipos em relação à adaptabilidade e estabilidade. As técnicas de Tocher e PCA permitiram a formação de clusters de genótipos semelhantes com base em uma estrutura multivariada. O GGE biplot indicou que os genótipos IMACV 690 e IMA08 WS foram altamente adaptáveis e estáveis para as principais características do algodão. O cruzamento dentre os genótipos IMACV 690 e IMA08 WS é o mais recomendado para aumentar o desempenho das principais características na cultura do algodão.

ABSTRACT: Understanding the genetic diversity and overcoming genotype-by-environment interaction issues is an essential step in breeding programs that aims to improve the performance of desirable traits. This study estimated genetic diversity and applied genotype + genotype-by-environment (GGE) biplot analyses in cotton genotypes. Twelve genotypes were evaluated for fiber yield, fiber length, fiber strength, and micronaire. Estimation of variance components and genetic parameters was made through restricted maximum likelihood and the prediction of genotypic values was made through best linear unbiased prediction. The modified Tocher and principal component analysis (PCA) methods, were used to quantify genetic diversity among genotypes. GGE biplot was performed to find the best genotypes regarding adaptability and stability. The Tocher technique and PCA allowed for the formation of clusters of similar genotypes based on a multivariate framework. The GGE biplot indicated that the genotypes IMACV 690 and IMA08 WS were highly adaptable and stable for the main traits in cotton. The cross between the genotype IMACV 690 and IMA08 WS is the most recommended to increase the performance of the main traits in cotton crops.

Abstract Multiple-trait best linear unbiased prediction (BLUP) is generally the most appropriate method to predict genetic values because it considers the genetic and residual correlations among traits and leads to higher selective accuracy. Thus, the aim of the present study was to analyze the interrelationships among traits related to cotton fiber length through path analysis under multiple-trait BLUP. To that end, 36 elite lines were evaluated in three envi ronments and phenotyped for fiber quality and agronomic traits. Variance components were estimated via residual maximum likelihood (REML). The genetic correlation coefficients among traits were obtained through the mixed model output, and a correlation network was constructed to graphically express these results. Subsequently, path analysis was performed considering fiber length as the main dependent variable. Genetic parameters indicate that the phenotypic variance for most traits is mainly composed of residual effects, which reinforces the need for more accurate statistical methods, such as multiple-trait BLUP. The results for genetic correlations and path analysis reveal the difficulty of selection based on important fiber quality traits, especially fiber length, since most traits show a low cause-and-effect relationship, while other important traits have an undesirable cause-and-effect relationship. Path analysis under multiple-trait BLUP proved to be suitable and useful for studying interrelationships among traits related to cotton fiber length.

Resumen La mejor predicción lineal insesgada de rasgos múltiples (BLUP) es, en general, el método más apropiado para predecir valores genéticos porque considera las correlaciones genéticas y residuales entre rasgos y conducta con mayor precisión selectiva. Por lo tanto, el presente estudio tuvo como objetivo estudiar las interrelaciones entre los rasgos relacio nados con la longitud de la fibra de algodón a través del análisis de ruta en BLUP de rasgos múltiples. Con este fin, se evaluaron treinta y seis líneas élite en tres ambientes y se fenotipificaron para muchos rasgos relacionados con la calidad de la fibra y los rasgos agronómicos. Los componentes de la varianza se estimaron mediante la máxima verosimilitud residual (REML). Los coeficientes de correlación genética entre rasgos se obtuvieron a través de la salida del modelo mixto, y para expresar gráficamente estos resultados se construyó una red de correlación. Posteriormente, realizamos el análisis de ruta considerando la longitud de la fibra como variable dependiente principal. Los parámetros genéticos indican que la variación fenotípica para la mayoría de los rasgos se compone principalmente de efectos residuales, lo que refuerza la necesidad de utilizar métodos estadísticos más precisos, como BLUP de rasgos múltiples. Los resultados encontrados para las correlaciones genéticas y el análisis de ruta revelan la dificultad de la selección basada en rasgos importantes de la calidad de la fibra, especialmente la longitud de la fibra, ya que la mayoría de los rasgos muestran una relación de causa y efecto muy baja, y otros rasgos importantes presentan una relación de causa y efecto no deseada. El análisis de ruta en BLUP de rasgos múltiples resultó ser adecuado y útil para el estudio de las interrelaciones entre los rasgos relacio nados con la longitud de la fibra de algodón.

Abstract: BRS 500 B2RF is a high-yielding cotton cultivar with transgenic resistance to lepidopteran pests and tolerance to the herbicide glyphosate. Additionally, BRS 500 B2RF has resistance to Ramularia leaf spot and partial resistance to root-knot nematode. It represents an important contribution to sustainable cotton production in Brazil.

ABSTRACT A better understanding of genetic diversity in cotton cultivars is needed to make the most of the genetic resources and guarantee continuing improvements in the breeding programs. Our objective was to evaluate the genetic diversity among cotton genotypes from the top breeding programs in Brazil and recommend hybrid combinations that would increase variability. The field experiments we conducted on three cotton genotypes from each of the following Brazilian breeding programs: EMBRAPA, MONSANTO DELTAPINE, FIBERMAX, IMA, TMG and UFU. Several phenotypic evaluations were carried out at V5, B1, full flower and full maturity. Moderate genetic divergence was observed among the genotypes from these breeding programs. Hybridization of the BRS 433 FL B2RF and FM 980 GLT genotypes would likely produce segregating populations with greater genetic variability, yield potential, lint yield and desirable fiber quality. Maturity, micronaire and fiber length were the strongest contributors to genetic divergence.

RESUMO O algodoeiro de fibra natural colorida tem recebido atenção dos programas de melhoramento na região semiárida do Nordeste brasileiro devido ao aumento no interesse por este tipo de fibra. Com isso, o objetivo deste trabalho foi selecionar genótipos de algodoeiro de fibra colorida quanto às características agronômicas e tecnológicas da fibra para as condições da região semiárida brasileira. O experimento foi realizado em dois ambientes (Patos-PB e Apodi-RN), na safra de 2016. O delineamento foi blocos ao acaso com quatro repetições. Foram utilizados 11 genótipos de fibra colorida e três testemunhas (BRS Topázio, BRS Rubi e BRS Verde), constituindo 14 tratamentos. As características avaliadas foram: Produtividade de algodão em caroço (PROD, kg.ha-1), Porcentagem de fibra (PF, %), Comprimento de fibra (COMP, mm), Resistência (RES, gf.tex-1) e Finura (FIN, µg.in-1). Os dados foram submetidos à análise de variância individual e conjunta e as médias foram agrupadas pelo teste de Scott e Knott (1974) a 0.05 de probabilidade. Os genótipos apresentaram variabilidade para as características estudadas com possibilidade de ganhos genéticos em ciclos posteriores de seleção. BRS Topázio, CNPA 2002 10245 e CNPA 2002 10327 apresentaram as melhores estimativas para as características avaliadas, sendo selecionados para futuros trabalhos de melhoramento do algodoeiro para o semiárido.

ABSTRACT Naturally-colored cotton fiber has received attention from breeding programs in the semiarid region of northeastern Brazil due to an increased interest in its fibers. Therefore, this study aimed to select genotypes of colored cotton fiber for agronomic and technological fiber characteristics for the Brazilian semi-arid conditions. The experiment was carried out in two environments (Patos-PB and Apodi-RN) in Brazil during the 2016 growing season. The experimental design was in randomized blocks with four replications. Treatments consisted of eleven colored fiber genotypes and three controls (BRS Topázio, BRS Rubi, and BRS Verde). The following traits were assessed: seed cotton yield (SCY, kg ha-1), lint percentage (LP, %), lint length (LEN, mm), lint strength (STR, gf tex-1), and lint micronaire (MIC, µg in-1). The data were submitted to individual and joint variance analyses, and means were grouped by the Scott and Knott (1974) test at 0.05 probability. Genotypes showed variability in all traits, which allows genetic gains in subsequent cycles of selection. The genotypes BRS Topázio, CNPA 2002 10245, and CNPA 2002 10327 presented the best estimates for the assessed traits, thus they can be selected for future studies in cotton breeding programs in the semiarid region.

Resumo Este estudo teve como objetivo estimar a força propulsora da braçada(FPB) em jovens nadadores do estilo livre e propor uma equação para estimar a força propulsora, considerando variáveis antropométricas e a maturação. Setenta e seis nadadores competitivos [meninos: n = 53; idade = 13,58 ± 1,79; meninas: n = 23; idade = 12,98 ± 1,79] participaram deste estudo. Foram avaliados: altura, massa magra, estatura sentada, comprimento da perna, envergadura, dobra cutânea do tríceps, área muscular do braço (AMB) e maturação. A força propulsiva da braçada foi medida pelo teste de nado atado. Uma regressão linear múltipla (modelo concorrente) foi usada para desenvolver a equação usando as variáveis AMB, envergadura e maturação. O método de Bland – Altman foi utilizado para comparar os valores encontrados entre FPB e força propulsiva estimada (FPE). Houve correlação significativa entre as variáveis FPB e AMB (R² = 0,12; p <0,01), envergadura (R² = 0,21; p <0,01) e maturação (R² = 0,20; p <0,01) para meninos, enquanto os valores das meninas foram: AMB (R² = 0,07; p = 0,20), envergadura (R² = 0,50; p <0,01) e maturação (R² = 0,44; p <0,01). Duas equações lineares foram estabelecidas para predizer a FPB em meninos e meninas. A análise de Bland-Altman mostrou concordância entre FPB e FPE. Em conclusão, a equação é uma ferramenta valiosa para monitorar o treinamento e ajudar a melhorar o desempenho do nadador.

Abstract This study aimed to estimate the propulsive force of the arm (PFA) in young freestyle swimmers and propose an equation to estimate propulsive force, considering anthropometric variables and maturity offset. Seventy-six competitive swimmers [boys: n= 53; age= 13.58 ± 1.79; girls: n= 23; age= 12.98 ± 1.79] participated in this study. Height, lean mass, sitting height, leg length, arm span, triceps skinfold, arm muscle area (AMA), and maturity offset were assessed. The propulsive force of the arm was measured by the tethered swim test. A multiple linear regression (concurrent model) was used to develop the equation using the variables AMA, arm span, and maturity offset. The Bland–Altman method was used to compare the values found between PFA and propulsive force–estimated (PFE). There was a significant correlation between the variables PFA and AMA (R²=0.12; p<0.01), arm span (R²=0.21; p<0.01), and maturity offset (R²=0.20; p<0.01) for boys, whilst in girls theses values were: AMA (R²=0.07;p=0.20), arm span (R²=0.50;p<0.01), and maturity offset (R²=0.44;p<0.01). Two linear equations were established to predict the PFA in boys and girls Bland-Altman analysis showed an agreement between PFA and PFE. In conclusion, the equation is a valuable tool to monitor training and help improve swimmer performance.

Abstract This study aimed to select cotton genotypes adapted to semi-arid conditions grown with supplementary irrigation. Two experiments were carried out between March and July 2016 in Serra Talhada- Pernambuco and Apodi-Rio Grande do Norte, Brazil. Eighteen elite genotypes bred by Embrapa Cotton and two controls (BRS 286 and BRS 336) were evaluated under drip and sprinkler irrigation. The experiment consisted of a randomized complete block design with four replications. Agronomic and fiber quality traits were evaluated. The data were subjected to individual and combined analysis of variance, and genotypes were selected by the Mulamba and Mock selection index (1978). The genetic parameters evidenced the possibility of significant gains in the selection process of cotton plants. The four genotypes (CNPA 2006-3052, CNPA 2004-266, CNPA 2006-1073, and CNPA 2005-125) with highest total genetic gains for the studied traits were considered the most promising.

RESUMO: O aprimoramento das características tecnológicas da fibra de algodão é uma demanda constante da indústria têxtil. Este trabalho teve como objetivo identificar o potencial de materiais melhorados com alta porcentagem de plumas para contribuir com alelos que aumentam a porcentagem de plumas com fibra extra longa (ELS) no algodão de terras altas. Dois materiais contrastantes para porcentagem de fibra (LP) e comprimento de fibra (FL) foram usados, um com fibra longa e uma baixa porcentagem de fibra (pai A) e outro com alta porcentagem de fibra e comprimento médio (pai B). As seguintes variáveis foram avaliadas: porcentagem de fibra (LP), comprimento médio da metade superior (UHML), uniformidade da fibra (FU), resistência da fibra (FS) e alongamento (EL). A análise dialélica foi realizada utilizando o Método 4 de Griffing adaptado para dialelo parcial. Os efeitos aditivos foram predominantes em relação aos efeitos não aditivos. O LP médio foi maior quando se usou o pai B. O oposto ocorreu para o UHML. Uma correlação negativa foi detectada entre LP e UHML, mostrando a dificuldade de obter ganho genético para ambas as características ao mesmo tempo.

ABSTRACT: Technological traits improvement of cotton fiber is a constant demand by textile industry. This research aimed to identify the potential of improved materials with high lint percentage to contribute with alleles that increase the lint percentage in Extra long staple fiber (ELS) upland cotton. Two contrasting materials for lint percentage (LP) and fiber length (FL) were used, one with long fiber and a low lint percentage (parent A) and another with high lint percentage and medium length (parent B). The following variables were evaluated: lint percentage (LP), upper half mean length (UHML), fiber uniformity (FU), fiber strength (FS), and elongation (EL). Diallel analysis was performed using the Griffing’s Method 4 adapted to partial diallel. Additive effects were predominant over non-additive effects. The mean LP was higher when using parent B. The opposite occurred for UHML. A negative correlation was detected between LP and UHML, showing the difficulty of obtaining genetic gain for both traits at the same time.

ABSTRACT Cotton provides about 90% of the world textile fiber, and is one of the crops of greater industrial relevance. The objectives of this study were to estimate the inbreeding depressionand the genetic effects involved in the control of the agronomic andfiber quality traits in F1 and F2 generations and to identify promising hybrids for obtaining superior cotton genotypes. Two cultivars of upland cotton and two moco (Brazilian endemic) cotton were crossed using a half-diallel scheme. The following traits were evaluated: percentage of fibers and weight of one boll, fiber length, fiber uniformity, short fiber index, fiber strength, and micronaire index. The additive genetic effects are predominant in the evaluated agronomic and fiber quality traits. Cultivar FM 966 is the most suitable parent to compose crossing blocks for the improvement of cotton agronomic and fiber quality traits. The hybrids FM 966 × CNPA 7MH and FM 966 × BRS 286 are the most promising for obtaining segregating populations aiming to select superior genotypes. Inbreeding depression is more pronounced in the agronomic traits than in the fiber quality traits.

ABSTRACT The objective of this work was to estimate the predicted genetic gains with the simultaneous selection of agronomic and technological traits from elite cotton lines using selection indexes. Data from the evaluation of 36 elite lines were evaluated in three trials located in Apodi-RN in 2013 and 2014 and Santa Helena, GO, Brazil in 2013, in a randomized block design with two replicates. The agronomic traits evaluated were: plant height (PH), average boll weight (ABW), percentage of fibers (PF) and seed cotton yield (YIE). In 20 bolls from each experimental unit, the following technological fiber traits were evaluated: fiber length (UHM), fiber uniformity (UNIF), short fiber index (SFI), fiber strength (FS), elongation (ELON), micronaire (MIC), reflectance (RD) and degree of yellowing (+b). Smith and Hazel, Pesek and Baker and Mulamba and Mock selection indexes were tested for selection of the seven superior genotypes, assigning the coefficients of genetic variation (CVg) as economic weight. There were no interaction between genotypes and environments for any of the evaluated traits. Smith and Hazel index resulted in negative gains for fiber length and positive for the traits whose reduction is of interest, such as plant height, micronaire and degree of yellowing. Pesek and Baker index provided positive predictive gains for all traits of interest. However, it promoted reduction only to the degree of yellowing. Mulamba and Mock presented satisfactory gains, being the most suitable for selecting genotypes aiming at simultaneous gains in yield and fiber technological components.

Abstract Fiber length is the main trait that needs to be improved in cotton. However, the presence of genotypes x environments interaction for this trait can hinder the recommendation of genotypes with greater length fibers. The aim of this study was to evaluate the adaptability and stability of the fibers length of cotton genotypes for recommendation to the Midwest and Northeast, using artificial neural networks (ANNs) and Eberhart and Russell method. Seven trials were carried out in the states of Ceará, Rio Grande do Norte, Goiás and Mato Grosso do Sul. Experimental design was a randomized block with four replications. Data were submitted to analysis of adaptability and stability through the Eberhart & Russell and ANNs methodologies. Based on these methods, the genotypes BRS Aroeira, CNPA CNPA 2009 42 and CNPA 2009 27 has better performance in unfavorable, general and favorable environment, respectively, for having fiber length above the overall mean of environments and high phenotypic stability.

Abstract Transgenic cotton cultivars BRS 430 B2RF and BRS 432 B2RF, medium and late season respectively, were developed by EMBRAPA in partnership with Bahia Foundation, aiming to create a high-yielding germplasm. The Bt toxins Cry1Ac and Cry2Ab target lepidopteran pests and the CP4-EPSPS gene confers tolerance to the herbicide glyphosate.

Abstract Information about combining ability is important in determining breeding strategies. The objective of this study was to estimate the general (GCA) and specific (SCA) combining abilities among twenty cotton hybrid combinations submitted to water stress, based on agronomic traits. The trails were carried out in semiarid environment (Barbalha, CE), during two years, in dry season under irrigation, and submitted to 23 days of water suppression. Wide variability was verified among parents and their hybrids, with additive effects to seed yield, lint percentage, blooming and boll weight. Dominance effect was found only to plant height. The combinations BRS 286 x CNPA 5M, BRS RUBI x CNPA 5M, FM 966 x CNPA 5M and BRS 286 x BRS Seridó showed the best SCAs and averages for the majority of the traits. In addition, at least one of their parents had high CGA. These combinations must be advanced in cotton breeding program.

RESUMO. Dentre os caracteres tecnológicos que ainda precisam ser melhorados no algodoeiro, destaca-se o comprimento das fibras. Deste modo, os objetivos com este trabalho foram quantificar as inter-relações entre caracteres agronômicos e tecnológicos de fibras e identificar caracteres que possam ser utilizados para a seleção indireta de genótipos de algodoeiro com maior comprimento de fibras. Foram avaliados caracteres agronômicos e tecnológicos em 36 linhagens elite de algodoeiro cultivadas em três ambientes. Foram estimadas as correlações canônicas entre dois grupos de caracteres: agronômicos e tecnológicos. Realizou-se análise de trilha considerando o comprimento de fibras como variável dependente principal. Os genótipos apresentaram variabilidade para todos os caracteres avaliados e não houve interação genótipos x ambientes significativa para nenhum caráter. É possível melhorar os principais caracteres tecnológicos do algodoeiro a partir da seleção indireta em caracteres agronômicos. A seleção de genótipos de algodoeiro com menor porte e maior peso médio de capulhos pode ser uma estratégia para aumentar o comprimento de fibras e melhorar os demais caracteres tecnológicos. Índices de seleção contendo altura de plantas, peso de capulhos, resistência e uniformidade de fibras é uma das principais estratégias para selecionar genótipos de algodoeiro com alta produtividade de algodão em caroço e fibras longas.

ABSTRACT. Fiber length stands out among technological traits as one that still needs to be improved in cotton. Thus, the objectives of this work were to quantify the interrelations between agronomic and technological fiber traits and to identify traits that could be used for the indirect selection of cotton genotypes with longer fiber lengths. Agronomic and technological traits were evaluated in 36 elite lines of cotton that were cultivated in three environments. Canonical correlations were estimated between two groups of traits: agronomic and technological. Path analysis was performed that considered fiber length as the primary dependent variable. The genotypes presented variability in all the evaluated traits, and no significant genotype vs. environmental interaction was observed for any of them. The main technological traits of cotton crops can be improved by an indirect selection of agronomic traits. The selection of cotton genotypes with a smaller size and a higher mean boll weight can be used to increase fiber length and improve other technological traits. Selection indices containing plant height, mean boll weight, fiber strength, and fiber uniformity can be one of the main strategies for the selection of cotton genotypes with a high yield of cotton bolls and long fibers.