Cowpea Breeding Research Articles

Evaluation and identification of high yielding and stable cowpea genotypes using GGE biplot and joint regression analysis for varietal development in East and Southern Africa

Malawi, Mozambique, and Tanzania's cowpea breeding programs have been collaborating on pre-breeding trials in different locations, focusing on key traits such as grain yield. However, there is a lack of information regarding the nature of genotype-environment interaction patterns among these environments. The study was conducted to assess and identify high-yielding and stable cowpea genotypes for the development of improved varieties in these three countries. Thirty genotypes were evaluated in ten environments using an incomplete block design with three replications. Grain yield data was analyzed using genotype (G) × genotype-environment interaction (GGE) biplot and joint regression analysis. The joint analysis of variance showed highly significant differences (P < 0.001) for the main effects of genotypes and environment, as well as their interaction effects. This suggested that the environments assessed were distinct and that the genotypes exhibited varying performances in response to environmental variations. The environmental indices showed that only four environments were favorable for high grain yield, and overall, Guariba was the topmost yielder (1973.5 kg ha−1) across all environments. The analysis identified IT10K-817-7 and MWcp08 as superior and stable genotypes, making them highly desirable and potentially recommended across test environments for their expected ability to achieve economically viable yields. Overall, Chitedze Research Station in Malawi and Nametil Research Station in Mozambique were both discriminating and representative, indicating that they are good test environments for selecting best-performing genotypes that can perform well across a wide range of conditions. These environments can be recommended as the best environments for future cowpea genotype evaluations targeting the release of varieties in the three countries (Malawi, Mozambique and Tanzania) where the METs were carried out.

Genetic Variability Studies for Identification of High Yielding Genotypes with High Protein Content in Grain Cowpea [Vigna unguiculata (L.) Walp.

Background: Cowpea is a major legume crop which has high protein content and provides a powerful tool to combat malnutrition due to its highly nutritional value. Identification of superior genotypes will aid in cowpea breeding program. Genetic variability is the foremost requirement in a breeding population for the selection of high yielding genotypes. To develop a new high yielding variety, it is important to study the genetic variability present in it so that proper and efficient selection could be done and most promising genotypes could be identified. Methods: Keeping this in mind, studies on genetic variability in grain cowpea was done utilizing 40 diverse exotic and indigenous cowpea genotypes which were evaluated for ten quantitative characters for two consecutive years 2020 and 2021. The experiment was planted in randomized block design with 3 replications at Pantnagar. Data was recorded on ten characters. Result: Mean squares were found to be highly significant for all the characters. Cluster analysis revealed five genetically diverse clusters. Cluster I had 8 genotypes, cluster II had 9 genotypes, cluster III consisted of 12 genotypes, cluster IV had 6 genotypes and Cluster V consisted 5 genotypes. Cluster I had the greatest intra-cluster distance (2.500) whereas cluster V had the smallest intra-cluster distance (1.701). In the cluster V, one of the genotype Pant Lobia-2 exhibited the highest mean values for all the characters. The highest GCV and PCV was recorded by number of pods per plant (28.87, 29.19) followed by yield (q/ha) (28.72, 29.04). The higher value of phenotypic component compared to the corresponding genotypic component suggest that there was an environmental influence on the performance of the genotypes. Correlation studies revealed positive correlation between pod length, pods per cluster, seeds per pod and yield quintal per hectare. Path coefficient analysis showed the significant positive direct relationship between plant height, peduncle length, pod length, number of pods per cluster, number of pods per plant and number of seeds per pod with yield quintals per hectare. The results of the study showed that, out of the 40 genotypes evaluated, Pant Lobia-2 exhibited the best performance. It has attractive red bold seeds with 31% protein content. Therefore it can be used in grain cowpea breeding program.

Canonical correlations between morphoagronomic and production traits in traditional cowpea varieties based on genotypic values

Obtaining information about the main morphoagronomic and yield components, as well as their interrelationships, is of utmost importance in cowpea breeding programs, aiming at the selection of superior genotypes. The analysis of canonical correlations allows us to predict and describe the relationship between groups of characters, allowing the indirect selection of superior genotypes. The objective of this work was to verify relationships between morphological characters and production components through the analysis of canonical correlations using genotypic values obtained via mixed REML/BLUP models in traditional cowpea varieties. The experiment was conducted in a randomized block design with three replications and 12 treatments. Traditional varieties were characterized and evaluated during the germination, seedling, flowering and harvest stages with data obtained from plants, pods and seeds. Using the genotypic correlation matrix, two sets of characteristics were established, Group I, formed by production components and Group II, formed by morphoagronomic characters. A second correlation analysis was performed to verify associations between morphoagronomic and seed traits (seed length, width and thickness). It was found that dependence between the groups evaluated and intergroup associations can be established, which allows the study of cause-effect and the practice of indirect selection between groups of variables studied. An increase in pod length, hundred-grain mass and seed size is achieved through the selection of early maturing plants, with greater width of the apical leaflet and length of the hypocotyl.

Genetic progress in cowpea [Vigna unguiculata (L.) Walp.] stemming from breeding modernization efforts at the International Institute of Tropical Agriculture.

Genetic gain has been proposed as a quantifiable key performance indicator that can be used to monitor breeding programs' effectiveness. The cowpea breeding program at the International Institute of Tropical Agriculture (IITA) has developed and released improved varieties in 70 countries globally. To quantify the genetic changes to grain yield and related traits, we exploited IITA cowpea historical multi-environment trials (METs) advanced yield trial (AYT) data from 2010 to 2022. The genetic gain assessment targeted short duration (SD), medium duration (MD), and late duration (LD) breeding pipelines. A linear mixed model was used to calculate the best linear unbiased estimates (BLUE). Regressed BLUE of grain yield by year of genotype origin depicted realized genetic gain of 22.75 kg/ha/year (2.65%), 7.91 kg/ha/year (0.85%), and 22.82 kg/ha/year (2.51%) for SD, MD, and LD, respectively. No significant gain was realized in 100-seed weight (Hsdwt). We predicted, based on 2022 MET data, that recycling the best genotypes at AYT stage would result in grain yield gain of 37.28 kg/ha/year (SD), 28.00 kg/ha/year (MD), and 34.85 kg/ha/year (LD), and Hsdwt gain of 0.48g/year (SD), 0.68g/year (MD), and 0.55g/year (LD). These results demonstrated a positive genetic gain trend for cowpea, indicating that a yield plateau has not yet been reached and that accelerated gain is expected with the recent integration of genomics in the breeding program. Advances in genomics include the development of the reference genome, genotyping platforms, quantitative trait loci mapping of key traits, and active implementation of molecular breeding.

Assessing Genetic Variability in Cowpea Yield Components and Seed Quality Parameters; A Comprehensive Review

Cowpea (Vigna unguiculata L. Walp) is an important leguminous crop with significant economic and nutritional value. In this comprehensive review, we delve into the genetic diversity observed in cowpea populations with a focus on yield components and seed quality parameters. Cowpea (Vigna unguiculata) is a crucial legume crop known for its nutritional value and adaptability to various agroecological conditions. Understanding the genetic variability within cowpea populations is essential for crop improvement programs aimed at enhancing yield components and seed quality parameters. This comprehensive review provides an overview of the methods used to assess genetic variability in cowpea, focusing specifically on yield components such as plant height, pod length, and seed weight, as well as seed quality parameters including protein content, amino acid composition, and mineral nutrient levels. Various factors influencing genetic variability in cowpea, such as domestication history, breeding systems, and environmental factors, are discussed. The implications of genetic variability for cowpea breeding and the development of improved varieties with enhanced yield and nutritional quality are also examined. Overall, this review highlights the importance of genetic variability assessment in cowpea for sustainable agriculture and food security.

Ex-ante priority setting in crop breeding: Towards inclusive innovation for impact

CONTEXTCrop breeding teams should ideally work a-priori to rank research priorities and varietal product concepts to make decisions considering social, environmental, production and market conditions that an improved crop variety will be entering upon release. Frequently, this research prioritization is guided by a cost-benefit optimization framing, which leaves the potential derived by alternative approaches, such as inclusive innovation, unexplored. OBJECTIVEIn this study, we apply PEEP (Participatory Ex-ante framework for Plant breeding), a new methodological framework for ex-ante participatory priority setting for plant breeding programs. This framework explores how, given a set of hypothetical crop varieties (varietal product concepts) it is possible to assess which will have the highest potential to deliver research impacts. PEEP is designed to support crop breeders to understand the impact potential of a new varietal product concept, and strategically make decisions based on this. METHODSPEEP ranks varietal product concepts across five impact domains: breeding, processing, marketing, climate, and cross-cutting themes. This paper reports on how an interdisciplinary breeding team from the Institute of Environment and Agricultural Research (INERA) in Burkina Faso working on cowpea (Vigna unguiculata [L.] Walp) applied PEEP and discusses the results from this application. We chose cowpea as a crop focus, based on prior research that showed that gender and social differences shape roles, responsibilities, and benefits from its cultivation in Burkina Faso. We engaged 650 stakeholders using tools and methods (choice experiment, surveys and focus group discussions) tailored to collect information according to their spheres of knowledge. RESULTS AND CONCLUSIONSWe present a reflection on the application process, results, and feedback from the INERA cowpea breeding team on these. We show that breeders and farmers ranked the potential impact of the varietal product concepts differently. We also show that differences in evaluation of impact from varietal product concepts vary based on market orientation, agroecological zones, farming systems and gender. SIGNIFICANCEWe demonstrate that PEEP contributes to inclusive agricultural innovation as a feasible method to consider the knowledge and preferences of diverse stakeholders. We show that it is informative to include diverse groups when conceptualizing new varieties before investing in varietal development. Making such research prioritization decisions early on enables breeding programs to avoid “missing the mark” on assumed impacts on smallholder women and men farmers and increases their visibility and voice in these upstream decisions.

Genetic Variability and Interrelationships of Grain, Cooking, and Nutritional Quality Traits in Cowpea: Implications for Cowpea Improvement

Grain quality, cooking quality, and nutritional quality traits are some of the major attributes that enhance the uptake and utilization of improved cowpea varieties. Therefore, there is a need for a better understanding of the genetic variation and inter-relationships among these quality traits in cowpeas to integrate them into cowpea breeding programs. This study was conducted to determine genetic variability among 306 cowpea genotypes for grain quality, cooking quality, and nutritional quality traits and to understand the interrelationships among these traits for exploitation in breeding programs. The results showed highly significant differences (p &lt; 0.001) among genotypes for grain quality, cooking quality, and nutritional quality traits. The mean performance for these quality traits was also very variable. These results suggest that genetic variability exists in the cowpea genotypes studied, which can be exploited in breeding programs aimed at developing high-performing varieties for the said traits. Significant (p &lt; 0.001) positive correlations were detected for protein content with iron and zinc. On the other hand, nutritional quality traits did not exhibit any association with grain quality or cooking quality traits. Cooking quality traits were also shown to be significantly and positively correlated with grain quality traits. This study has identified several genotypes with desirable quality-related traits that could be used in crossing programs to generate improved varieties with consumer-preferred traits to improve the food, income, and nutritional status of many smallholder farmers that largely depend on cowpeas.

Dissecting the Genetic Diversity of USDA Cowpea Germplasm Collection Using Kompetitive Allele Specific PCR-Single Nucleotide Polymorphism Markers.

Cowpea (Vigna unguiculata L. Walp) is an important grain legume crop of the subtropics, particularly in West Africa, where it contributes to the livelihoods of small-scale farmers. Despite being a drought-resilient crop, cowpea production is hampered by insect pests, diseases, parasitic weeds, and various abiotic stresses. Genetic improvement can help overcome these limitations, and exploring diverse cowpea genetic resources is crucial for cowpea breeding. This study evaluated the genetic diversity of 361 cowpea accessions from the USDA core collection for the species using 102 Kompetitive Allele Specific PCR (KASP) single nucleotide polymorphism (SNP) markers. A total of 102 KASP-SNP was validated in the germplasm panel, and 72 showed polymorphism across the germplasm panel. The polymorphism information content (PIC) of all SNPs ranged from 0.1 to 0.37, with an average of 0.29, while the mean observed heterozygosity was 0.52. The population structure revealed three distinct populations that clustered into two major groups after phylogenetic analysis. Analysis of molecular variance (AMOVA) indicated greater genetic variation within populations than among populations. Although cowpea generally has a narrow genetic diversity, the accessions used in this study exhibited considerable variation across geographical regions, sub-species, and improvement status. These results indicated that the selected KASP genotyping assay can provide robust and accurate genotyping data for application in the selection and management of cowpea germplasm in breeding programs and genebanks.

Understanding specific gender dynamics in the cowpea value chain for key traits to inform cowpea breeding programs in Malawi, Mozambique and Tanzania.

Cowpea is an important food and nutrition security crop in Malawi, Mozambique and Tanzania and it is mainly produced by women farmers mainly on a subsistence scale. The majority of these farmers use local varieties despite the availability of improved varieties in the region. Low acceptability and adoption of improved varieties have also hampered cowpea breeding efforts. The low adoption, especially among women farmers, has been attributed to the failure by breeding programs to involve farmers in the process of designing and developing improved varieties with a view to meeting their priorities and preferences. Despite women constituting the majority of cowpea farmers in these countries, no comprehensive gender analysis on cowpea value chain had been instituted to understand the traits that are gender and youth responsive and how to incorporate them in the product profiling so that the developed varieties benefit men, women and youth. The main objective of the gender study was, therefore, to identify preferred traits by different gender groups within the whole cowpea value chain to inform cowpea breeding programs in the three countries. The study employed quantitative and qualitative methods to elucidate preferences, including value chain mapping, a quantitative survey of farmers, focus group discussions and key informant interviews targeting farmers/consumers, traders, policymakers and processors. Results showed that the top-ranking traits in order of importance across the countries and gender were; (1) high grain yield, (2) good grain taste, (3) early maturity time, (4) large grain size, (5) good leaf taste and (6) short cooking time. It was further noted that different gender groups preferred almost similar traits though minor variations were noted in terms of prioritization of these traits. These results have had two major influences on our cowpea breeding program: firstly, the breeding program changed the way it prioritizes traits to include ones that reflect the needs of men, women and the youth in the cowpea value chain. Secondly, our breeding objectives are closely aligned to gender differences in the target population of farmers and other users, by incorporating key priority traits that address the needs of both men and women, including the youth. That is to say, product targets and specific product profiles are more gender sensitive. Since the breeding work is ongoing, the expectation is that the development of improved varieties resulting from this gender sensitive process will translate into higher adoption levels of these varieties (compared with previous releases), which might have ripple effects on food, nutrition and income security in the region.

Morphological diversity, correlation studies, and multiple-traits selection for yield and yield components of local cowpea varieties

Abstract The evaluation of the diversity in the cowpea local varieties (CLVs) allows the efficient use of genetic resources for cultivar development. This study aimed to evaluate the diversity of CLVs based on observation of morphological characteristics and to identify the relationship among morphological traits and potential varieties as donor genes to improve yield potential. The CLVs were collected from five provinces in Indonesia during 2017–2018. The evaluation of the performance of CLVs’ morphological characteristics was carried out in the Indonesian Legumes and Tuber Crops Research from March to July 2019. The observed data were 43 agronomic characters which consist of qualitative and quantitative characters. There is a high variation in stem pigmentation and seed color in 214 CLVs. There were nine qualitative characters with no variation. Most quantitative characters showed significant variation among CLVs. The clustering of 214 CLVs results in five clusters in which some CLVs maintain valuable characteristics that could be used in the breeding program. The number of pods per plant, number of racemes per plant, and 100 seed weight were useful for indirect selection in the yield improvement. Based on the genotype by trait biplot, the CLV 112, 191, and 111 could be used as donor parents for seed size improvement and the CLV 169 could be used as a donor parent for the yield potential improvement in the cowpea breeding program. Four cowpea genotypes can be recommended for commercial release or used as potential breeding material in cowpea cultivar development programs. The new findings of this study could provide a basis for the genetic improvement of cowpea.

A Mid-Density Single-Nucleotide Polymorphism Panel for Molecular Applications in Cowpea (Vigna unguiculata (L.) Walp).

Molecular markers are increasingly being deployed to accelerate genetic gain in crop plants. The objective of this study was to assess the potential of a mid-density genotyping panel for molecular applications in cowpea breeding. A core set of 2,602 targeted diversity array technology (DArTag) single-nucleotide polymorphisms (SNPs) was designed from an existing 51,128 Cowpea iSelect Consortium Array. The panel's usefulness was assessed using 376 genotypes from different populations of known genetic backgrounds. The panel was informative, with over 78% of SNPs exceeding a minor allele frequency of 0.20. The panel decoded three stratifications in the constituted population, as was expected. Linkage disequilibrium (LD) decay was correctly depicted as slower in a biparental subset than in other populations. A known flower and seed coat color gene region was located on chromosome Vu07, suggesting that the mid-density panel may be used to hypothesize genomic regions underlying target traits in cowpea. Unexpected heterozygosity was detected in some lines and highly among F1 progenies, divulging the panel's potential application in germplasm purity and hybridity verification. The study unveils the potential of an excellent genomic resource that can be tapped to enhance the development of improved cowpea cultivars.

Characterization of terminal flowering cowpea (Vigna unguiculata (L.) Walp.) mutants obtained by induced mutagenesis digs out the loss-of-function of phosphatidylethanolamine-binding protein

Cowpea (Vigna unguiculata (L.) Walp) is one of the major food legume crops grown extensively in arid and semi-arid regions of the world. The determinate habit of cowpea has many advantages over the indeterminate and is well adapted to modern farming systems. Mutation breeding is an active research area to develop the determinate habit of cowpea. The present study aimed to develop new determinate habit mutants with terminal flowering (TFL) in locally well-adapted genetic backgrounds. Consequently, the seeds of popular cowpea cv P152 were irradiated with doses of gamma rays (200, 250, and, 300 Gy), and the M1 populations were grown. The M2 populations were produced from the M1 progenies and selected determinate mutants (TFLCM-1 and TFLCM-2) from the M2 generation (200 Gy) were forwarded up to the M5 generation to characterize the mutants and simultaneously they were crossed with P152 to develop a MutMap population. In the M5 generation, determinate mutants (80–81 days) were characterized by evaluating the TFL growth habit, longer peduncles (30.75–31.45 cm), erect pods (160°- 200°), number of pods per cluster (4–5 nos.), and early maturity. Further, sequencing analysis of the VuTFL1 gene in the determinate mutants and MutMap population revealed a single nucleotide transversion (A-T at 1196 bp) in the fourth exon and asparagine (N) to tyrosine (Y) amino acid change at the 143rd position of phosphatidylethanolamine-binding protein (PEBP). Notably, the loss of function PEPB with a higher confidence level modification of anti-parallel beta-sheets and destabilization of the protein secondary structure was observed in the mutant lines. Quantitative real-time PCR (qRT-PCR) analysis showed that the VuTFL1 gene was downregulated at the flowering stage in TFL mutants. Collectively, the insights garnered from this study affirm the effectiveness of induced mutation in modifying the plant’s ideotype. The TFL mutants developed during this investigation have the potential to serve as a valuable resource for fostering determinate traits in future cowpea breeding programs and pave the way for mechanical harvesting.

Assessing the effects of 24-epibrassinolide and yeast extract at various levels on cowpea’s morphophysiological and biochemical responses under water deficit stress

BackgroundDue to the factor of water deficit, which has placed human food security at risk by causing a 20% annual reduction in agricultural products, addressing this growing peril necessitates the adoption of inventive strategies aimed at enhancing plant tolerance. One such promising approach is employing elicitors such as 24-epibrassinolide (EBR) and yeast extract, which are potent agents capable of triggering robust defense responses in plants. By employing these elicitors, crops can develop enhanced adaptive mechanisms to combat water deficit and improve their ability to withstand drought condition. This study investigates the impact of different levels of EBR (0, 5, 10 µm) and yeast extract (0 and 12 g/l) on enhancing the tolerance of cowpea to water deficit stress over two growing seasons.ResultsThe findings of this study demonstrate that, the combined application of EBR (especially 10 µm) and yeast extract (12 g/l) can increase seed yield (18%), 20-pod weight (16%), the number of pods per plant (18%), total chlorophyll content (90%), and decrease malondialdehyde content (45%) in cowpea, compared to plants grown under water deficit stress without these treatments. Upon implementing these treatments, impressive results were obtained, with the highest recorded values observed for the seed yield (1867.55 kg/ha), 20-pod weight (16.29 g), pods number per plant (9), and total chlorophyll content (19.88 mg g−1 FW). The correlation analysis indicated a significant relationship between the seed yield, and total chlorophyll (0.74**), carotenoids (0.82**), weight of 20 seeds (0.67**), and number of pods (0.90**). These traits should be prioritized in cowpea breeding programs focusing on water deficit stress.ConclusionsThe comprehensive exploration of the effects of EBR and yeast extract across various levels on cowpea plants facing water deficit stress presents a pivotal contribution to the agricultural domain. This research illuminates a promising trajectory for future agricultural practices and users seeking sustainable solutions to enhance crops tolerance. Overall, the implications drawn from this study contribute significantly towards advancing our understanding of plant responses to water deficit stress while providing actionable recommendations for optimizing crop production under challenging environmental conditions.

A Genome-Wide Association Study Reveals Region Associated with Seed Protein Content in Cowpea.

Cowpea (Vigna unguiculata L. Walp., 2n = 2x = 22) is a protein-rich crop that complements staple cereals for humans and serves as fodder for livestock. It is widely grown in Africa and other developing countries as the primary source of protein in the diet; therefore, it is necessary to identify the protein-related loci to improve cowpea breeding. In the current study, we conducted a genome-wide association study (GWAS) on 161 cowpea accessions (151 USDA germplasm plus 10 Arkansas breeding lines) with a wide range of seed protein contents (21.8~28.9%) with 110,155 high-quality whole-genome single-nucleotide polymorphisms (SNPs) to identify markers associated with protein content, then performed genomic prediction (GP) for future breeding. A total of seven significant SNP markers were identified using five GWAS models (single-marker regression (SMR), the general linear model (GLM), Mixed Linear Model (MLM), Fixed and Random Model Circulating Probability Unification (FarmCPU), and Bayesian-information and Linkage-disequilibrium Iteratively Nested Keyway (BLINK), which are located at the same locus on chromosome 8 for seed protein content. This locus was associated with the gene Vigun08g039200, which was annotated as the protein of the thioredoxin superfamily, playing a critical function for protein content increase and nutritional quality improvement. In this study, a genomic prediction (GP) approach was employed to assess the accuracy of predicting seed protein content in cowpea. The GP was conducted using cross-prediction with five models, namely ridge regression best linear unbiased prediction (rrBLUP), Bayesian ridge regression (BRR), Bayesian A (BA), Bayesian B (BB), and Bayesian least absolute shrinkage and selection operator (BL), applied to seven random whole genome marker sets with different densities (10 k, 5 k, 2 k, 1 k, 500, 200, and 7), as well as significant markers identified through GWAS. The accuracies of the GP varied between 42.9% and 52.1% across the seven SNPs considered, depending on the model used. These findings not only have the potential to expedite the breeding cycle through early prediction of individual performance prior to phenotyping, but also offer practical implications for cowpea breeding programs striving to enhance seed protein content and nutritional quality.

Plant fruit extracts enhance the in vitro propagation of cowpea (Vigna unguiculata) on Murashige and Skoog media

Cowpea (Vigna unguiculata) is a versatile legume with diverse nutritional and nutraceutical properties that serve as a food security and medicinal crop for millions of households across Africa. An efficient protocol was developed to propagate shoot tip and cotyledonary node explants from six cowpea breeding accessions in vitro on Murashige and Skoog (MS) basal media supplemented with either banana extract, coconut water, orange or tomato juice. Micropropagation performance was compared to MS medium supplemented with B5 vitamins. A total of 500 plantlets were obtained in vitro across treatments and MS basal media supplemented with tomato juice had the highest micropropagation performance (154 plantlets), followed by banana extract (112 plantlets), orange juice (107 plantlets), and coconut water (82 plantlets). Three accessions (AGRAC 216, TA, and Asontem) were found to be the most amenable to in vitro propagation using plant-derived extracts. Overall, this study successfully established that plant-derived extracts can support in vitro cowpea propagation in the absence of synthetic plant growth regulators.

Agro-morphological characterization of selected varieties of vegetable cowpea [Vigna unguiculata (L.) Walp.] in Burkina Faso

Vegetable Cowpea (Vigna unguiculata) is one of the neglected legumes in Burkina Faso, and as a result, its genetic diversity remains poorly known. The main aim of this study was to know its genetic variability through an agro-morphological characterization. Twenty vegetable cowpea varieties were evaluated at the Kamboinsé Environmental, Agricultural and Training Research Center following a three-replication Fischer block design under rainfed conditions. Fifteen quantitative and nine qualitative variables were collected and subjected to various statistical analyses. Analysis of variance was significant for the variables 50% flowering, vegetable cowpea date, number of pods obtained per plant, number of seeds per pod, fresh pod weight, fresh pod yield, pod length, plant height, seed length and chlorophyll content. Strong correlations were also reported between the various variables. The observed diversity is structured in three morphological groups viz., Group 1 consists of individuals with early flowering, high chlorophyll content and the number of pods obtained per plant. Group 2 brings together the varieties of average agronomic performance for pod length, the number of pods per plant, number of days at 95% maturity, fresh pod weight, yield of fresh pods and group 3 of varieties with long pods, early green date, high pod weight and good fresh pod yield. Among the tested varieties, the varieties IT83S-872 (30 pods), IT84S-2246 (27 pods), Baguette (25 pods), IT83S-818 (26 pods), and IT85F-2682 (24 pods) stood out for their high pod production. In addition, the varieties of vegetable cowpea baguette, baguette grimpant, Telma, and IT83S-911 showed the best performance in terms of early vegetable cowpea date stage, longest pods, highest pod weight and best yield of fresh pods. The high genetic variability level within the tested varieties could be exploited in future green cowpea breeding programmes.

Parâmetros genéticos e índices de seleção de genótipos de feijão-caupi para produção de grãos verdes

ABSTRACT Cowpea is a legume that is grown worldwide and used for different purposes, especially as green grains. However, considering the low availability of cowpea cultivars for green grain production, selecting genotypes that have better traits for this purpose is necessary. In this context, the objective of this study was to estimate genetic parameters and evaluate different selection indices for identifying superior cowpea genotypes and subsidizing cowpea breeding programs focused on green grain production. A field experiment was conducted at the Center of Agricultural Sciences of the Federal University of Ceará (UFC), Ceará, Brazil. The treatments consisted of 42 cowpea genotypes from the Active Germplasm Bank of the UFC. Fourteen traits were used for characterization. The experiment was conducted in an augmented block design with four controls. The data obtained were subjected to analysis of variance, and genetic parameters, correlations, and selection indices were determined. The traits days to flowering (DFL), days to fruiting (DFR), green pod weight (GPW), green pod width (GW), green pod length (GPL), green pod thickness (GPT), number of grains per pod (NGP), and green grain thickness (GGT) showed heritability higher than 70%, indicating that selection in an early generation is favorable. The genetic correlations between the trait pairs DFL×DFR, GPW×GPL, and GW×GGT were higher than the phenotypic and environmental correlations. Genotypes CE-228, CE-688, CE-994, CE-165, CE-796, and BRS-Paraguaçu showed simultaneous superiority for the evaluated traits and are the most appropriate for green grain production.

Seleção de genótipos de feijão-caupi para caracteres nutricionais

ABSTRACT Cowpea is a worldwide consumed legume due to its high nutrient concentrations. Selecting genotypes with high nutrient concentrations can contribute to developing biofortified cultivars. This study aimed to evaluate the nutritional potential and indicate genotypes of Vigna unguiculata for genetic improvement based on nutritional traits. Forty-three cowpea genotypes belonging to the Active Germplasm Bank of the Federal University of Ceará were used in the study. The analyses of dry matter, ash, ether extract, proteins, and minerals (phosphorus, potassium, calcium, magnesium, sulfur, sodium, copper, iron, zinc, manganese, and boron) were performed in triplicate. The data were subjected to analysis of variance, means comparison test, genetic parameters, nutritional quality indexes, and the sum of ranks. Genetic variances predominated concerning environmental variation for the nutrient concentrations of cowpea can be transmitted to future generations. The CE-0151, CE-0189, CE-0207, CE-0228, CE-0248, CE-0542, CE-0685, CE-0686, CE-0796, CE-0997, and CE-1002 genotypes are indicated for selection for continuing the biofortified cowpea breeding program.

Breeding Cowpea for Adaptation to Intercropping for Sustainable Intensification in the Guinea Savannas of Nigeria

Cowpea is a multifaceted crop; however, considerable challenges affect the production of this crop despite its comparatively better adaptation to harsh environments. Most smallholder farmers in West Africa cultivate this crop in intercropping systems where its low plant population does not allow the full expression of the cultivars’ yield potential. This is because most varieties currently grown in intercrop have been developed in and for monocropping, although some breeding programs recently have focused on intercrop systems. This study, therefore, aimed to evaluate the performance of some newly developed cowpea breeding lines for adaptation to intercropping systems. Firstly, an on-station field experiment was conducted in 2018. The selected promising lines and a standard check were evaluated in three locations in an intercropping system and on-farm trials. Significant differences were observed among the cowpea genotypes for all the traits measured. Two improved lines, UAM14-122-17-7 and UAM14-123-18-3, had superior grain and fodder yields under sole and intercropping systems and in different agroecological systems, revealing their adaptability. Based on our findings, UAM14-122-17-7 and UAM14-123-18-3 are recommended for a cereal-cowpea mixture because they are adapted to intercropping and produce high-grain yield under intercrop and sole-cropping systems.

Modeling covariance structures for genetic and non‐genetic effects in cowpea multi‐environment trials

AbstractIn cowpea breeding, multi‐environment trials are conducted to select lines with high yield. The occurrence of genetic and/or statistical imbalance is common in these experiments, in addition to the possibility of (co)variance between genetic and non‐genetic effects. We explore the restricted maximum likelihood/best linear unbiased prediction features to select the model with the most appropriated covariance structure and compare the results with the traditional model (homogenous variances and no covariances). Then, 17 inbred lines and three cultivars were evaluated in six experiments during two crop years in the semiarid zone of Northeast Brazil. The trait evaluated was the 100‐grain weight. We selected the best model considering the Akaike Information Criterion. The model with diagonal structure for the residual effects and heterogeneous compound symmetry for the genetic effects had the best fit. The predicted genetic gain of lines selected in this model was 1.18% higher compared to the traditional model. Modeling different (co)variance structures for genetic and non‐genetic effects is an efficient approach in selecting superior genotypes in multi‐environment trials in cowpea breeding.