Search Results (92)

Induced mutation plays an integral part in plant breeding as it introduces new variability among the population. A study was conducted in cowpeas [Vigna unguiculata (L.) Walp] to assess the yield divergence, heritability, genetic advance, and correlation among the M5 Tswana cowpea mutants. The experiment utilized seven genotypes under rainfed and supplementary irrigation during the 2022/23 and 2023/24 cropping seasons. The mutant lines demonstrated significant variations in days to 50% emergence (DE) and days to 50% flowering (DF). Tswana emerged earlier (5–7 days) and flowered in 21–54 days across the two seasons, compared to some of the mutant lines. The yield and yield components varied among some mutant lines and the control. Most importantly, mutants outperformed the Tswana control for some of these traits, indicating potential for genetic improvement. An analysis of genetic parameters revealed minimal environmental influences on some of the observed traits (GH, PN, GY), while others showed little environmental impact. Variation in heritability (H²) and genetic advance (GA%) between the two seasons limited the contribution of genotypic effects in the expression of the studied traits. Correlation analysis revealed strong and significant positive associations between DE and GH, as well as between DF and PW. Most traits, except DF and PW, were positively correlated with grain yield (GY), although the correlations were not significantly different. Cluster analysis grouped the genotypes into four distinct clusters. Principal component analysis (PCA) revealed the superiority of mutant lines (Tswana-300Gy-214, Tswana-400Gy mutant lines, and Tswana-500Gy-31) in their association with improved GY, pod weight (PW), 100-seed weight (100-SW), and seed number per pod (SN/P). Interestingly, the Tswana control formed a separate cluster and diverged from the mutants in PCA, suggesting that induced mutagenesis effectively targeted genes controlling the traits considered in this study. Full article

Cowpea (Vigna unguiculata [L.] Walp) is a vital food security crop in sub-Saharan Africa, including Eswatini. The productivity of the crop is low (<600 kg/ha) in the country due to a lack of improved, locally adapted, and farmer-preferred varieties with biotic and abiotic stress tolerance. The objective of the study was to assess the agronomic performance of newly developed elite cowpea mutants to select best-yielding and adapted pure lines for production and genetic improvement in Eswatini. A total of 30 cowpea genotypes, including 24 newly developed advanced mutant lines, their 3 founder parents and 3 local checks, were profiled for major agronomic traits in two selected sites (Lowveld Experiment and Malkerns Research Stations) using a 6 × 5 alpha lattice design with three replications. A combined analysis of variance revealed that the genotype x location interaction effects were significant (p < 0.05) for germination percentage (DG %), days to flowering (DTF), days to maturity (DMT), number of pods per plant (NPP), pod length (PDL), number of seeds per pod (NSP), hundred seed weight (HSW), and grain yield (GYD). Elite mutant genotypes, including NKL9P7, BRR4P11, SHR9P5, and NKL9P7-2 exhibited higher grain yields at 3158.8 kg/ha, 2651.6 kg/ha, 2627.5 kg/ha, and 2255.8 kg/ha in that order. The highest-yielding mutant, NKL9P7, produced 70%, 61%, and 54% more grain yield than the check varieties Mtilane, Black Eye, and Accession 792, respectively. Furthermore, the selected genotypes displayed promising yield components such as better PDL (varying from 13.1 to 26.3 cm), NPP (15.9 to 26.8), and NSP (9.8 to 16.2). Grain yield had significant positive correlations (p < 0.05) with DG %, NSP, and NPP. The principal component analysis (PCA) revealed that 81.5% of the total genotypic variation was attributable to the assessed quantitative traits. Principal component (PC) 1 accounted for 48.6%, while PC 2 and PC 3 contributed 18.9% and 14% of the overall variation, respectively. Key traits correlated with PC1 were NPP with a loading score of 0.91, NSP (0.83), PDL (0.73), GYD (0.68), HSW (0.58), DMT (−0.60), and DTF (−0.43) in a desirable direction. In conclusion, genotypes NKL9P7, BRR4P11, SHR9P5, NKL9P7-2, Bira, SHR3P4, and SHR2P7 were identified as complementary parents with relatively best yields and local adaptation, making them ideal selections for direct production or breeding. The following traits, NPP, NSP, PDL, GYD, and HSW, offered unique opportunities for genotype selection in the cowpea breeding program in Eswatini. Full article

The genus Vigna Savi (Leguminosae Juss.) comprises approximately 150 species, classified into five subgenera, most of which exhibit a diploid chromosome number of 2n = 22. However, the wild species Vigna lasiocarpa (Benth) Verdc. (V. subg. Lasiospron) is notable for its dysploid chromosome number of 2n = 20. This study aimed to elucidate the chromosomal events involved in the karyotype evolution of V. lasiocarpa (Vla). We used oligopainting probes from chromosomes 1, 2, 3, and 5 of Phaseolus vulgaris L. and two barcode probes from the genome of V. unguiculata (L.) Walp. Additionally, bacterial artificial chromosomes (BACs) from V. unguiculata and P. vulgaris, along with a telomeric probe from Arabidopsis thaliana (L.) Heynh., were hybridized to V. lasiocarpa metaphase chromosomes to characterize Vla3, Vla7/5, and Vla9. Our findings revealed conserved oligo-FISH patterns on chromosomes 2, 6, 8, 10, and 11 between V. unguiculata and V. lasiocarpa. Paracentric and pericentric inversions were identified for Vla3 and Vla9, respectively. Our integrative approach revealed that the dysploid chromosome originated from an “end-to-end fusion” of homoeologous chromosomes 5 and 7. This is the first report on the chromosomal mechanisms underlying descending dysploidy in Vigna, providing new insights into the evolutionary dynamics of the genus. Full article

Despite the fact that cowpea is one of the most drought-tolerant legumes, some genotypes with a high yield under well-watered conditions have been shown to be susceptible to drought stress, thus requiring further improvement. The objectives of this study were to conduct a genome-wide association study (GWAS) for drought tolerance in cowpea. A total of 331 cowpea genotypes were evaluated for drought tolerance. After SNP filtering, 5,884,299 SNPs were used to conduct GWAS using BLINK. The results showed: (1) a significant GWAS peak defined by a cluster of 196 significant SNPs and mapped on a 210 kb region of chromosome 5 was identified to be a good locus candidate for tolerance to trifoliate leaf chlorosis under drought stress in cowpea, (2) a strong GWAS peak was found towards the end of chromosome 1 and this peak was a good candidate locus for tolerance to unifoliate leaf chlorosis under drought stress in cowpea, and (3) a total of 25 SNPs located on chromosomes 1, 3, 5, and 11 were significantly associated with plant greenness under drought stress. This study provides a better understanding of the molecular genetics of drought tolerance in cowpea and the findings can be expanded to other crop species. Full article

Cowpea (Vigna unguiculata (L.) Walp.) is a vital legume crop recognized for its nutritional value and adaptability to various growing conditions. However, exposure of cowpea to drought stress during the early growth stages can significantly restrict growth and yield potential. Therefore, identifying cowpea genotypes tolerant to drought during early growth and development is essential for maintaining yield potential. This study characterized 15 diverse cowpea genotypes for various physiological, pigment, and morphological traits that may contribute to drought tolerance. At the V2 stage, the cowpea genotypes were subjected to two moisture regimes: control (100% irrigation) and drought (50% irrigation) for 22 days to assess trait responses and their relationship to drought tolerance. Drought-stressed plants decreased stomatal conductance by 79%, negatively correlating with a 2.9 °C increase in canopy temperature. Under drought, the photochemical reflectance index (PRI) was strongly associated with the quantum yield of PSII and electron transport rate. Shoot biomass decreased by 51% and root biomass by 32% under drought. Leaf area and shoot weight were correlated with root traits such as total length, surface area, and weight. Among all genotypes, 280785-11 and UCR 1004 demonstrated superior rooting vigor under drought, emphasizing their efficiency in resource utilization. These findings highlight the relevance of utilizing drought-adaptive traits to improve early-season drought tolerance. Full article

Soil salinity is one of the most severe impacts of climate change, negatively affecting plant growth and development. Seed germination and seedling emergence are among the most critical stages susceptible to salt stress, making it important to explore them to identify the most resilient accessions for crop yield improvement. Cowpea (Vigna unguiculata L. Walp.) is an important crop due to its ability to fix atmospheric nitrogen, improving soil health, and its high protein content. The main objectives of this study were to screen salt-resilient cowpea accessions from a worldwide collection and to evaluate cowpea responses to salt stress at germination stage through gene expression analysis. A total of 40 cowpea accessions from sixteen different countries were subjected to two treatments: control (water) and salt stress (150 mM NaCl solution). The seeds germinated, and the seedlings grew for ten days. The germination and growth parameters and lipid peroxidation quantification were determined. The results revealed significant differences in all parameters among accessions and treatments. A high variation in salt responses was detected among accessions, allowing the selection of five accessions (Co_2, Co_4, Co_21, Co_30, Co_31) as resilient to salt stress at germination stage. Subsequently, two salt stress-related genes (DREB2 and VuEXO) were evaluated through qPCR, revealing genotype-dependent regulation. These results provide valuable insights for the early selection of salt-resilient cowpea accessions, which may be considered for the development of improved and new varieties in the future. Full article

Biochar is a multifunctional tool that enhances soil quality, with particularly positive effects on acidic soils with low nutrient content, common in tropical regions worldwide, such as in the Amazon region in Brazil. This study investigates the effects of açaí fruit waste biochar (Euterpe oleracea Mart.) amendment and phosphate fertilisation on the chemical characteristics of a Ferralsol and on the biological components of cowpea (Vigna unguiculata (L.) Walp). In a greenhouse setting, a randomised block design was employed, testing five doses of biochar (0, 7.5, 15, 30, and 60 t ha⁻¹) combined with four doses of phosphorus (P) (0, 40, 80, and 120 kg ha⁻¹), resulting in 20 treatments with three replicates and 60 experimental units. Cowpea responded to inorganic fertilisation, with lower doses of P limiting the biological components (height, leaves, leaf area, dry biomass, and dry root mass). Higher doses of biochar and P increased the soil’s available P content by up to 2.3 times, reflected in the P content of cowpea dry biomass. However, this increase in biochar and P levels led to a maximum increase of 7.7% in agronomic phosphorus efficiency (APE) in cowpea in the short term. The higher doses of biochar promoted increases in pH value, cation exchange capacity (CEC), and the contents of potassium (K), calcium (Ca), and total nitrogen (N). In contrast, a decrease in magnesium (Mg) and aluminium (Al) levels was observed, while the concentration of easily extractable glomalin (EE-GRSP) was not significantly affected during the evaluated period. We conclude that biochar altered the soil environment, promoting the increased solubility and availability of phosphorus. Full article

To face climate change, searching for alternative crops resistant to drought and heat stress becomes necessary, along with efficient germplasm management. Old landraces well-adapted to local climatic conditions, pests, and pathogens could be used as a source of desired traits. Cowpea (Vigna unguiculata L. Walp.), grown mainly in the tropical and subtropical areas, presents superior drought and heat stress adaptation compared to other legumes. Limited information is available on field performance and nutrient qualities of cowpea landraces originating from southern Bulgaria. The aim of the present study was to compare in field conditions and their impacts on plant performance, yield, and the seed biochemical composition of Bulgarian cowpea accessions, including fourteen landraces and one variety. Higher-yielding, earlier-maturing accessions were discerned. Among the landraces studied, B1E0103 was the most productive under the agro-climatic conditions in Sadovo, central Bulgaria; BOE0035 had the earliest maturity. The seed moisture content was 11.5 ± 0.3%, and the energy value was 347.9 ± 1.2 kcal/100 g. The crude protein content varied from 22.5 to 27%, the lipids were 1.6–2.55%, the carbohydrates were 56.5–61.4%, ash was 3.8–4.3%, dietary fibers were 3.1–4.5%, tannins were 16–22%, phenols were 1.3–4.4 mg/g, flavonoids were 1.85–3.7 mg/g, and the trypsin-inhibiting activity was 0.7–2.5 units/mg FW, with the lowest in BOE0010, the variety “Hrisi”, and B1E0103 and the highest in B0E0035, A9E1230, and A8E0562. Landraces are promising genetic material for future research and breeding purposes. Full article

Despite the high nutritional value of cowpea and its potential for sustainable farming, its cultivation is limited by the lack of vegetable varieties adapted to different soil and climatic conditions, which complicates the fight against food insecurity in many countries. Therefore, this study aims to conduct a comprehensive evaluation of cowpea (Vigna unguiculata (L.) Walp. subsp. sesquipedalis (L.) Verdc.) varieties with the aim of identifying genotypes with high productivity potential and resistance to the main adverse environmental factors of the Right-Bank Forest-Steppe of Ukraine. The experimental study was carried out in a three-year period (2014–2016). Depending on the variant of the experiment, cowpea germination was observed from 25 May to 30 May. The shortest sowing–shoot period (10 days) was observed in the variety ‘U-Tya-Kontou’ (China), with the longest (13 days) in the varieties ‘Kafedralna’ (Ukraine) and ‘American Improved’ (USA). In the control variant, shoots were obtained on 28 May. Flowering started from 9 July to 16 July; technical maturity (unripe (green) beans) started from 27 July to 2 July; and biological maturity of the seeds started from 30 August to 5 September. For the variety ‘American Improved’, the shortest period of seedling–technical maturity (unripe (green) beans) (58 days) and seedling–biological maturity (92 days) was recorded. By cultivar, the maximum plant height was achieved with varieties ‘Groik’ (Israel) at 100.5 cm and ‘Gasson’ (Vietnam) at 61.8 cm, which are 52 cm and 13.3 cm more than the control height. They differ by the quick growth of the main and side shoots, which allows them to be grown on supports. The highest yield of green beans was recorded in the cowpea variety ‘Gasson’ at 14.4 t∙ha⁻¹, which is 38.5% higher than the control. In the variety ‘Groik’, the yield of green beans (11.4 t∙ha⁻¹) did not differ significantly from the control (‘Kafedralna’—10.4 t∙ha⁻¹). The varieties ‘U-Tya-Kontou’ and ‘American Improved’ were characterized by the lowest yield of green beans, which reached 5.8 and 4.2 t∙ha⁻¹, respectively, which is 44.2 and 59.6% less than the control. As a result of statistical analysis of cowpea yields, the limits of its fluctuation were established as follows: fluctuations in the sum of effective temperatures by 10 °C (>10 °C) contributed to a deviation in green bean yields from 20.0 to 24.7 kg (ha)⁻¹, and fluctuations in precipitation by 10 mm contributed to a deviation in green bean yields in the range from 34.3 to 208.2 kg (ha)⁻¹. The results of the study presented in this article have practical application for the development of effective methods of growing local varieties of long-stemmed cowpea, which will increase yields and meet the needs of both farmers and consumers in regions with similar climatic conditions. Full article

Selenium (Se) is a beneficial element for plants and is essential for human nutrition. In plants, it plays an important role in the formation of selenocysteine and selenomethionine and in the activation of hydrolytic enzymes, which can aid in seed germination and reduce abiotic stress during germination. The objective of this study was to evaluate the effects of the application of selenium sources and rates to the soil on the physiological quality of cowpea seeds. The experimental design was a randomized block with four replications and a factorial scheme (7 × 2). Two sources of Se (sodium selenate and sodium selenite) and seven rates (0, 2.5, 5, 10, 20, 40 and 60 g ha⁻¹) were used. Physiological characterization was carried out by first counting of germination, germination, emergence, accelerated aging, cold testing, electrical conductivity, length and dry biomass of shoots and roots. Germination after accelerated aging increased with selenate, even at higher rates, whereas selenite provided benefits at lower rates. Selenation linearly increased germination after the cold test and linearly reduced electrolyte leakage as the Se rate increased. The soil application of Se is beneficial for cowpea seed quality. Compared with those treated with sodium selenite, cowpea plants treated with sodium selenate through the soil produce more vigorous seeds. The application of 10 g ha⁻¹ Se in the form of sodium selenate provides seedlings with faster germination and root development and is an alternative for rapid stand establishment. Full article

Cowpea is one of the most important leguminous crops in Sub-Saharan Africa (SSA), and moisture stress is among the constraints affecting its productivity. This study was conducted to understand the response of cowpea accessions to moisture stress. A total of 255 cowpea accessions from Togo and four checks from the International Institute of Tropical Agriculture (IITA), were assessed. The trials were conducted in the glasshouse and an open field (which was divided into moisture-stressed (MS) and non-moisture-stressed fields (NMS)). In the non-moisture-stressed environment compared to the moisture-stressed environment, there was a greater heritability for agronomic traits such as biomass, seed weight, and pod weight. The accessions with the highest seed weights (yield-related traits), surpassing the checks under both moisture-stressed and non-moisture-stressed conditions in the field, were six viz.: RK173 (49.8 g (MS); 90.4 g (NMS)), RP225 (34.6 g (MS); 119.9 g (NMS)), RP232 (33.4 g (MS); 51.9 g (NMS)), RM357 (27.9 g (MS); 62.9 g (NMS)), RK148 (23.9 g (MS); 63.4 g (NMS)), and Vu081_2_2 (21.8 g (MS); 46.7 g (NMS)). The most promising accession was RK173; this was ranked first under the moisture-stressed condition and ranked second under the non-moisture-stressed condition with a loss in weight of 44.9% due to drought stress. Of the top 20 accessions that recovered after watering resumed in the glasshouse screening, only the following 9 had a recovery percentage higher than 5% viz.: RS029 (34.5%), RK014 (14.2%), RS114 (9.6%), RK121 (8.3%), RS007 (7.6%), RK123 (7.3%), RS037 (7.3%), RS101 (5.6%), and RS108 (5.1%). The best line and those with a higher recovery percentage could be exploited further in order to improve them in future drought breeding programs by crossing them with lines susceptible to drought or using other drought breeding techniques. Full article

Cowpea (Vigna unguiculata (L.) Walp.) is an important legume cultivated mainly in regions with limited water availability across the African and American continents. Its productivity is significantly affected by environmental stresses. Thaumatin-like proteins (TLPs), which belong to the PR-5 (pathogenesis-related 5) protein family, are known to be responsive to both biotic and abiotic stresses. However, their role remains controversial, with some TLPs associated with plant defense (particularly against fungal infections) and others associated with abiotic stresses response. In this study, we evaluated the structural diversity and gene expression of TLPs in cowpea (VuTLPs) under different stress conditions, including biotic [mechanical injury followed by inoculation with Cowpea Aphid-borne Mosaic Virus (CABMV) or Cowpea Severe Mosaic Virus (CPSMV)] and abiotic (root dehydration). Genomic anchoring of VuTLPs revealed 34 loci encoding these proteins. Neighbor- joining analysis clustered the VuTLPs into three distinct groups. We identified 15 segmental duplication and 6 tandem duplication gene pairs, with the majority of VuTLP genes found to be under purifying selection. Promoter analysis associated VuTLPs with bHLH, Dof-type, and MYB- related transcription factors, supporting their diverse roles. Diversity in VuTLP function was also observed in their expression profiles under the studied stress conditions. Gene expression data showed that most VuTLPs are recruited within the first minutes after biotic stress imposition. For the root dehydration assay, the most transcripts were up-regulated 150 min post-stress. Moreover, the gene expression data suggested that VuTLPs exhibit functional specialization depending on the stress condition, highlighting their diverse roles and biotechnological potential. Full article

Cowpea (Vigna unguiculata (L.) Walp.) is appreciated for its suitability for cultivation and obtaining good yields in relatively extreme farming conditions. It is resistant to high temperatures and drought. Moreover, food products prepared from Vigna are rich in many nutrients such as proteins, amino acids, carbohydrates, minerals, fiber, vitamins, and other bioactive compounds. However, in East and Southeast Asia, where the products of this crop are in demand, the climate is characterized by excessive humidity. Under these conditions, the vast majority of cowpea varieties tend to have indeterminate growth (elongated shoot length) and are unsuitable for mechanized harvesting. The molecular mechanisms for tolerance to high relative humidity remain the least studied in comparison with those for other abiotic stress factors (drought, heat, cold, flooding, etc.). The purpose of the work was to reveal and investigate differentially expressed genes in cowpea accessions having contrasting growth habits (determinate and indeterminate) under humid and drought conditions. We performed RNA-seq analysis using selected cowpea accessions from the VIR collection. Among the genotypes used, some have significant changes in their plant architecture in response to high relative humidity, while others were tolerant to these conditions. In total, we detected 1697 upregulated and 1933 downregulated genes. The results showed that phytohormone-related genes are involved in cowpea response to high relative humidity. DEGs associated with jasmonic acid signaling are proposed to be key contributors in the maintenance of compact architecture under humid conditions. Full article

Megalurothrips usitatus (Bagnall) feeds on the young tissues of plants, causing wilting and deformity of leaves as well as damage to flowers and fruits, thereby seriously affecting plant yield. Due to its small size and difficulty of control, the species is one of the most important pests in the legume family. To clarify the occurrence and damage pattern of M. usitatus on field crops, a study was conducted using eight different crops as experimental materials, and an age-stage, two-sex life table was constructed. The population density of M. usitatus was the highest on cowpeas (Vigna unguiculata L. Walp.), followed by green beans (Phaseolus vulgaris L.) and Vigna cylindrica (Vigna unguiculata subsp. cylindrica (L.) Verdc.) in terms of net reproductive rate and the intrinsic rate of increase. In terms of reproductive capacity, cowpeas and V. cylindrica were more suitable for M. usitatus growth and reproduction, followed by green beans. M. usitatus could develop into adults on courgettes (Cucurbita pepo L.), wax gourds (Benincasa hispida Thunb. Cogn.), Momordica charantia (Momordica charantia L.), and soybeans (Glycine max L. Merr.) but had difficulty reproducing on those plants. Cucumber (Cucumis sativus L.) was the least suitable for the survival of M. usitatus. Population parameter analysis showed that the cowpea was the most suitable host plant for M. usitatus, followed by green beans and V. cylindrica. M. usitatus had difficulty reproducing on courgette, wax gourd, M. charantia, and soybeans, and feeding on cucumbers inhibited M. usitatus development and reproduction. Full article

Chemical desiccation is widely used in agriculture to anticipate harvest and mitigate the effects of adverse environmental conditions. It is applied to both grains and seeds. Although this practice is widely used, there are still significant gaps in understanding the effects of different herbicide application times on seed quality and plant physiological responses. The objective of this study was to evaluate the effects of different herbicide application times on cowpea, focusing on seed quality, physiological responses, and biochemical composition, including chlorophylls, carotenoids, sugars, and proline, under nocturnal desiccation. In the first experiment, eight herbicides and two mixtures were applied at night: diquat, flumioxazin, diquat + flumioxazin, glufosinate ammonium, saflufenacil, carfentrazone, diquat + carfentrazone, atrazine, and glyphosate. All of the tested herbicides caused a reduction in normal seedling formation, with the diquat + carfentrazone combination resulting in 100% abnormal seedlings. A significant decrease in chlorophyll levels (chlorophyll a: 63.5%, chlorophyll b: 50.2%) was observed using diquat, which indicates damage to photosynthetic processes, while the carotenoid content increased. Total soluble sugars and proline were also negatively impacted, reflecting physiological stress and metabolic changes in seedlings. In the second experiment, three application times were tested with diquat, diquat + flumioxazin, and diquat + carfentrazone. Nocturnal application showed the most significant reduction in chlorophyll levels and increased carotenoid levels. Application at noon and late afternoon also significantly changed the soluble sugar and proline levels. These results indicate that the herbicide application time directly influences the seeds’ physiological quality. Full article