ABSTRACT Cowpea [Vigna unguiculata (L.) Walp.] is an important socioeconomic crop in Brazil, mainly in the Northeast and more recently in the Midwest of Brazil. Charcoal rot caused by Macrophomina phaseolina (Tassi) Goid, is an important disease in semiarid regions, where edaphoclimatic conditions are favorable to the development of disease. The aim of this study was to evaluate the response of 100 cowpea lines to two isolates of M. phaseolina. The experiments were conducted in a completely randomized design, with five replications (two plants per pot). The main variables evaluated were lesion length and relative growth compared to control (RGCC). Among the evaluated accessions, 15% of the lines were resistant to isolate 59 and 11% of the lines were resistant to isolate CMM 2106 of M. phaseolina. Therefore, these accessions can be used as a source of resistance to M. phaseolina by farmers directly as new cultivars or in future hybridizations of cowpea genetic breeding programs.

ABSTRACT Iron and zinc deficiency is one of the main problems affecting vulnerable populations in the Colombian Caribbean, thereby generating malnutrition from the consumption of foods with low content of essential minerals. The objective of this study was to evaluate the genotype-environment interaction for iron and zinc accumulation in grains in 10 cowpea bean genotypes by additive main effects and multiplicative interaction (AMMI) model and to select the most stable ones to stimulate their planting or as parents in the genetic improvement program. Nine promising lines and a commercial control were evaluated using the randomized complete block design with 10 treatments and four replications in 10 environments of the northern Colombia in the second semester of 2017 and first of 2018. The adaptability and stability analysis was done using AMMI model. The results showed highly significant differences at the level of environments, genotypes, and genotype-environment interaction for iron and zinc, demostrating a differential adaptability of genotypes in the test environments. Genotypes 2 and 3 expressed greater adaptability and stability for iron contents in the seed; while genotype 1, recorded it for zinc contents. These three genotypes outperformed the commercial control and, therefore, can be recommended for planting or be used as parents in the genetic improvement program.

ABSTRACT Fusarium wilt, caused by soil-borne Fusarium oxysporum f. sp. tracheiphilum (Fot), can reduce cowpea bean yield. Considering that genetic control through resistant genotypes is pivotal for Fusarium wilt control, the aim of the present study was to identify cowpea genotypes that are resistant to Fot from the Germplasm Bank of the Pernambuco Agronomic Institute, Embrapa Middle North, and other producing areas in the North and Northeast regions of Brazil. The cultivar BR-17 Gurguéia was used as a susceptible control and MNC01-649F-2-1 was used as a resistant control. Two experiments were carried out in a completely randomized design in the greenhouse of the Department of Agronomy of the University Federal Rural of Pernambuco. Plants with the first pair of expanded leaves were inoculated with a conidial suspension (106 conidia/mL) using the conidia root-immersion methodology. Fusarium wilt severity in plants was assessed 21 d after inoculation, with the aid of a descriptive scale. In the first experiment, we evaluated the resistance of 38 cowpea genotypes, of which 19 (5 moderately resistant and 14 resistant) were selected for the second experiment. In the first experiment, four genotypes (Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante) did not show any symptoms of Fusarium wilt. In the second, 15 genotypes showed high resistance to Fot, including Canapu PE and Miranda IPA 207, which again had no symptoms of Fusarium wilt. In conclusion, this study identified that the genotypes, Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante have greater resistance to Fusarium wilt.

ABSTRACT Given the lack of information on the use of spontaneous plants from the Caatinga biome as green manure to produce green grains, the present work aimed to agronomically and economically optimize cowpea production for green grains and their components when fertilized with equitable biomass amounts of hairy woodrose (Merremia aegyptia L.) and roostertree (Calotropis procera Ait.) in two cropping seasons in a semi-arid environment. The experiment used a randomized complete block design, with five treatments and five replicates. The treatments consisted of equitable amounts of dry M. aegyptia and C. procera biomass of 16, 29, 42, 55 and 68 t ha-1. In each experiment, an additional treatment was planted with cowpea without fertilizer (absolute control), and another was fertilized with mineral fertilizer for the purpose of comparison with the treatment of maximum physical or economic efficiency. The maximum optimized physical (agronomic) efficiencies of cowpea green pods and grain production were reached in the productivity of green pods at 3.90 t ha-1 and green grains at 4.06 t ha-1, with incorporation into the soil of 45.07 and 50.48 t ha-1 of green manure, respectively. The maximum economic efficiency of cowpea green grain production was reached at a net income of R$5826.12 ha-1 and at a rate of return of 1.29 reals for each real invested with application to the soil of 38.74 and 37.85 t ha-1 of the tested green manure biomass.

ABSTRACT Cowpeas (Vigna unguiculata L. Walp) are an economically and socially important legume in northern and north-eastern Brazil and can establish effective symbiosis with nitrogen-fixing bacteria. We evaluated the symbiotic compatibility and efficiency of rhizobial strains from Pernambuco semi-arid soils and determined their symbiotic stability on the IPA-206, BR 17-Gurguéia, and BRS Novaera cultivars, selected for different environments. The experiment was conducted in a greenhouse to evaluate a 3 × 28 factorial arrangement (cultivars selected for different environments × inoculation with the currently recommended strain, uninoculated plants with or without mineral nitrogen, and 25 rhizobial strains from semi-arid soils) in a randomized block design with four replicates. We determined nodule number, shoot and root dry matter, nodule dry matter by nodule number, nitrogen accumulated in the shoot by nodule dry matter, nitrogen content and accumulation in the shoot, relative efficiency of the recommended strain based on nitrogen accumulation, and shoot dry matter. Overall, the cultivars responded differently to different strains and cultivar biological nitrogen fixation potential. Strains G7.85 and BR 3262 showed potential for biological nitrogen fixation. BR 3262 was confirmed to be adequate for inoculation of different cowpea cultivars.

RESUMO O feijão-caupi é uma leguminosa de grande importância socioeconômica para as regiões Norte e Nordeste do Brasil. Entretanto, ainda necessita de mais estudos que avaliem seu desempenho produtivo quando cultivado em regime irrigado e sob diferentes densidades de plantas. Objetivou-se, neste trabalho, avaliar os efeitos de diferentes regimes hídricos e densidades de plantas na produtividade de grãos, componentes de produção e eficiência do uso de água, bem como a correlação da produtividade de grãos com os componentes de produção da cultivar de feijão-caupi BRS Tumucumaque. O experimento foi conduzido na área experimental da Embrapa Meio-Norte, Teresina, Piauí, de junho a setembro de 2017, em um Argissolo Vermelho-Amarelo eutrófico. Utilizou-se o delineamento em blocos casualizados, sob esquema de parcelas subdivididas, com quatro repetições, em que os regimes hídricos ocuparam as parcelas (187,7; 233,5; 263,5 e 288,7 mm) e as densidades de plantas, as subparcelas (12; 16; 20 e 24 plantas m-2). Foram avaliados o número de vagens por planta, o número de vagens por metro quadrado, o comprimento de vagens, a produtividade de grãos secos e a eficiência de uso da água. A máxima produtividade de grãos foi de 1.694,46 kg ha-1 com aplicação da lâmina de 288,7 mm e a densidade de 20,4 plantas m-2. O componente de produção número de vagens por metro quadrado foi o que mais se correlacionou com a produtividade de grãos. | ABSTRACT Cowpea is a legume of great socioeconomic importance for the North and Northeast regions of Brazil. However, studies to evaluate its production performance when cultivated under irrigated regime and under different plant densities are necessary. The objective of this work was to evaluate the effects of different water regimes and different plant densities on grain yield, production components and water use efficiency, and on the correlation between grain yield and production components of BRS Tumucumaque cowpea cultivar. The experiment was carried out at Embrapa Meio-Norte experimental area, in Teresina, Piauí State, Brazil, from June to September 2017, in an Argissolo Vermelho-Amarelo eutrófico (Ultisol). A randomized complete block design was used, in a split-plot scheme with four replicates, in which the water regimes occupied the plots (187.7; 233.5; 263.5 and 288.7 mm) and plant densities, the subplots (12; 16; 20 and 24 plants m-2). The number of pods per plant, number of pods per square meter, pod length, dry grain yield and water use efficiency were evaluated. The maximum dry grain yield reached was 1,694.46 kg ha-1, with application of 288.7 mm and density of 20.4 plants m-2. The production component number of pods per square meter was the most correlated with dry grain yield.

RESUMO Variedades tradicionais são fontes de variabilidade genética, principalmente no que se refere a alelos que conferem tolerância a fatores bióticos e abióticos e, portanto, podem auxiliar os programas de melhoramento no desenvolvimento de cultivares promissoras. Contudo, torna-se necessário conhecer esse patrimônio genético em nível que permita sua pretensa utilização em programas de melhoramento genético. Assim, objetivou-se com esse estudo: (i) identificar variedades tradicionais de feijão-caupi que apresentem potencial agronômico e (ii) avaliar a diversidade genética das mesmas para orientação de futuros cruzamentos. Para tal, dois ensaios (litoral e sertão do estado do Ceará) foram realizados em períodos distintos para a caracterização morfoagronômica de oito variedades tradicionais do estado do Ceará mais duas cultivares testemunhas. Ambos os ensaios foram realizados no delineamento em blocos ao acaso com quatro repetições. Adicionalmente, foi feita a caracterização molecular por marcadores ISSR. Devido a presença de interação genótipos por ambientes, observou-se que para as condições do litoral (Fortaleza), a variedade tradicional Boi Deitado foi a mais indicada, e para as condições do sertão (Madalena) foi a Vinagre Barrigudo de Caldo, por serem superiores quanto ao rendimento de grãos e quanto a outros caracteres agronômicos. Buscando ampliar a base genética do feijão-caupi, sugerem-se cruzamentos entre os genótipos Boi deitado e Cojó para a geração de populações segregantes em futuros programas de melhoramento. | ABSTRACT Landraces are sources of genetic variability, especially with respect to alleles that confer tolerance to biotic and abiotic factors and, therefore, can aid breeding programs in the development of promising cultivars. However, it is necessary to know this genetic patrimony at a level that allows its alleged use in breeding programs. In this sense, the objective of this study was: (i) to identify cowpea landraces that present agronomic potential and (ii) to evaluate the genetic diversity for future cross-breeding. For this, two trials (coastal and sertão of the state of Ceará) were carried out in distinct periods for the morphological and agronomic characterization of eight landraces of the state of Ceará plus two control cultivars. Both assays were conducted in a randomized complete block design with four replicates. Additionally, the molecular characterization by ISSR markers was done. Due to the presence of interaction genotypes by environments, it was observed for the conditions of the coast (Fortaleza), the traditional variety Boi Deitado and the conditions of the sertão (Madalena) to Vinagre Barrigudo de Caldo, as the most indicated to be superior in grain yield and in other agronomic characters. In order to increase the genetic base of the cowpea, we suggest crosses between genotypes Boi deitado and Cojó for the generation of segregating populations of future breeding programs.

ABSTRACT Cowpea has great socioeconomic importance, especially in the North and Northeast of Brazil, and its genetic improvement has become increasingly relevant. This study aimed to assess the genetic divergence among cowpea genotypes of the active germplasm bank of the Agronomic Institute of Pernambuco to indicate the most divergent and productive as parents aiming at enriching its breeding program in this institution. The experiment was carried out at the experimental station of Itapirema, Goiana, PE, in a randomized block design with four replications. Thirty genotypes were used in the study, being two of them the controls (Miranda IPA 207 and Paulistinha). The parameters flowering, number of pods per peduncle, number of pods per plant, pod length, ten pod weight, grain index, number of grains in ten pods, hundred-grain weight, grain yield per hectare, plant habit, color of flowers, leaves, pods, and grains, and grain shape were assessed. Genetic divergence was observed among the cowpea genotypes. Pod length and weight, flowering, hundred-grain weight, and the number of pods per plant were the main contributors to genetic divergence. Crosses indicated to enable new gene combinations more favorable for cowpea are Pitiúba x Cabeçudo, Pitiúba x Manteiga, and Pitiúba x Costela de Vaca. | RESUMO O feijão-caupi possui grande importância socioeconômica, principalmente nas regiões Norte/Nordeste do Brasil. Devido a este fator o melhoramento genético dessa espécie vem se tornando cada vez mais relevante. O trabalho teve como objetivo avaliar a divergência genética entre genótipos de feijão-caupi do Banco Ativo de Germoplasma do Instituto Agronômico de Pernambuco (IPA), a fim de indicar os mais divergentes e produtivos como genitores de forma a enriquecer o programa de melhoramento da cultura nessa instituição. O ensaio foi conduzido na Estação experimental de Itapirema (IPA), Goiana-PE, em delineamento experimental de blocos casualizados com quatro repetições. Utilizaram-se 30 genótipos sendo duas testemunhas (Miranda IPA 207 e Paulistinha). Foram avaliados: início de floração, número de vagem/pedúnculo, número de vagem/planta, comprimento médio de vagem, peso de dez vagens, peso dos grãos de dez vagens, índice de grãos, número de grãos em dez vagens, peso de cem grãos, rendimento de grãos/hectare, porte, cor da flor, da folha, da vagem e do grão e a forma do grão. Existe divergência genética entre os genótipos de feijão-caupi avaliados. As características peso de vagem, início da floração, comprimento da vagem, peso de cem grãos e número de vagens por planta foram as que mais contribuíram para a divergência genética. Os cruzamentos indicados para viabilizar novas combinações gênicas mais favoráveis são: Pitiúba x Cabeçudo, Pitiúba x Manteiga e Pitiúba x Costela de Vaca.

ABSTRACT The objective of this study was to evaluate genetic divergence among cowpea genotypes and to select parents for crosses aimed at the fresh pod and grain market. Two experiments were carried out during 2014, corresponding to two sowing times, in the municipality of Mossoró, State of Rio Grande do Norte. Twenty-three cowpea genotypes were evaluated in a randomized complete block design with four replicates. Fifteen descriptors were used to quantify divergence, using the Mahalanobis distance as a measure of dissimilarity, obtained from the genotypic mean predicted by the Restricted Maximum Likelihood/Best Linear Unbiased Prediction (REML/BLUP) method. The Unweighted Pair Group Method with Arithmetic Mean (UPGMA) hierarchical method was used to group genotypes and the Singh criterion to quantify the contribution of traits to genetic divergence. The genotype × environment interaction (G × E) influenced divergence, both in the contribution of traits and in the grouping of genotypes. In the experiment 1, the genotypes were distributed among four groups. In the experiment 2, less discrimination occurred and the genotypes were represented by only two groups. When joint analysis of two evaluations was carried out based on two sowing times, genotypes were represented by six groups. The G × E interaction influences the contribution of traits and the grouping of cowpea genotypes in the study of divergence. The genetic divergence of the set of cowpea genotypes evaluated is mainly due to green grain and pod yield. BRS Aracê and BRS Xiquexique cultivars are the most divergent among the genotypes studied, representing 75% of the recommended crosses. | RESUMO O objetivo deste trabalho foi avaliar a divergência genética entre genótipos de feijão-caupi e selecionar genitores para cruzamentos visando o mercado de vagens e grãos verdes. Foram conduzidos dois experimentos, correspondendo a duas épocas de semeadura, no município de Mossoró, Rio Grande do Norte, ano 2014. Foram avaliados 23 genótipos de feijão-caupi em delineamento de blocos casualizados com quatro repetições. Foram utilizados 15 descritores para quantificar a divergência, utilizando como medida de dissimilaridade a distância de Mahalanobis, obtida a partir da média genotípica predita pelo método REML/BLUP. Utilizou-se o método hierárquico UPGMA para agrupar os genótipos e o critério de Singh para quantificar a contribuição dos caracteres para a divergência genética. A interação genótipos x ambientes influenciou a divergência, tanto na contribuição dos caracteres quanto no agrupamento dos genótipos. Na primeira época de cultivo os genótipos foram distribuídos em quatro grupos. Na segunda época ocorreu menor discriminação, sendo que os genótipos formaram apenas dois grupos. Ao realizar-se o agrupamento com base na análise conjunta das duas avaliações, realizadas nas duas épocas de semeadura os genótipos foram agrupados em seis grupos. A interação genótipos x ambientes influencia a contribuição das características e o agrupamento dos genótipos de feijão-caupi no estudo de divergência. A divergência genética do conjunto de genótipos de feijão-caupi avaliados é devida principalmente a produtividades de grãos verdes e de vagens verdes. As cultivares BRS Aracê e BRS Xiquexique foram os genótipos mais divergentes entre os estudados, fazendo parte de 75% dos cruzamentos recomendados.

ABSTRACT Cowpea bean is a socioeconomically important legume that contribute to generate employment and income. This species presents great grain variability, and the commercial subclass black eye stands out as a very appreciated grain in Brazil and abroad, thus requiring the development of new cultivars. The objective of this work was to evaluate and select lineages of commercial black eye cowpea, based on simultaneous, and direct selection. First, 105 progenies and four controls were evaluated using the Federer's augmented block design. Seventy-seven progenies, selected from this evaluation-first selection cycle-and four controls were evaluated in three environments, using a simple 9×9 lattice design. Based on this evaluation, the second selection cycle was possible, resulting in 24 progenies. The gain by direct selection was lower than the predicted gain for grain yield in the first cycle, indicating that the selection was not effective. This result was probably due to the reduced genetic variability caused by the selection pressure. In the second cycle, the predicted and observed gains were similar, indicating that much of the expected gain was observed. The predicted and observed gains, with simultaneous selection based on the rank sum selection index, were similar in the first and second cycle. The simultaneous and direct selections resulted in genetic gains for grain yield in the two selection cycles, making it possible the selection of high grain yield lineages. | RESUMO O feijão-caupi é uma leguminosa socioeconomicamente importante, contribuindo com a geração de emprego e renda. É uma espécie que apresenta grande variabilidade para o tipo de grão, sendo a subclasse comercial fradinho a que se destaca por ser um grão muito apreciado no Brasil e no exterior, demandando o desenvolvimento de novas cultivares. Este trabalho foi realizado com o objetivo de avaliar e selecionar linhagens de feijão-caupi tipo comercial fradinho, baseada na seleção simultânea e seleção direta. Inicialmente foram avaliadas 105 progênies e quatro testemunhas, utilizando o delineamento Blocos Aumentados de Federer. A partir desta avaliação foram selecionadas 77 progênies (primeiro ciclo de seleção), e quatro testemunhas que foram avaliadas em três ambientes, utilizando o delineamento látice simples 9x9. Fundamentado nessa avaliação, foi possível realizar o segundo ciclo de seleção, resultando em 24 progênies. Pela seleção direta, o ganho realizado foi inferior ao ganho predito para produtividade no primeiro ciclo, indicando que a seleção não foi efetiva, provavelmente devido à redução da variabilidade genética ocasionada pela pressão de seleção. No segundo ciclo, os ganhos realizado e predito foram bem próximos, indicando que grande parte do ganho esperado foi concretizado. Para os ganhos com a seleção simultânea baseados no Índice de Soma de Ranks, os valores de ganho predito e realizado foram semelhantes no primeiro e segundo ciclo. As seleções, simultânea e direta, possibilitaram a obtenção de ganhos genéticos para produtividade nos dois ciclos de seleção, possibilitando a seleção de linhagens de alta produtividade.