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The cowpea aphid (Aphis cracivora) is a cosmopolitan insect pest that causes economic damage on cowpea. Although the pest persists at all the growth stages of the crop, in West Africa, aphids are the only major insect pests that farmers regularly control at the vegetative stage. Thus, deploying aphid-resistant crop varieties can reduce farmers' expenditure on insecticide. The availability of different biotypes of the pest and reports of resistance breakdown necessitates pyramiding of sources of aphid resistance to develop a more robust genotype for durable resistance. Two aphid-resistance genes, sourced from SARC-1-57-2 and IT97K-556-6, were introgressed through gene pyramiding technique into a farmers’ preferred cowpea variety, Zaayura, using marker-assisted backcrossing. A simple sequence repeat (SSR) marker, CP 171F/172R, and an allele-specific single nucleotide polymorphism (SNP) marker, 1_0912, were used for foreground selection of the SARC-1-57-2 and IT97K-556-6 aphid resistance genes, respectively. A stepwise backcross approach was used to introgress the major aphid resistance QTL (QAc-vu7.1) from IT97K-556-6 into Zaayura using the marker 1_0912 coupled with intermittent screening under artificial aphid infestation. After the fourth backcross generation, three heterozygous BC4F1 of Zaayura/TT97K-556-6 were intercrossed to Zaayura Pali to develop intercross F1 (ICF1). Three true ICF1 hybrids allowed to self to produce ICF2. Five (5) out of 48 ICF2 plants which were genotyped with the two foreground markers had the two aphid resistance genes fixed in the double homozygous dominant state. For background selection, out of 192 allele-specific markers screened, only 47 polymorphic markers were identified and used for the background analysis of the pyramided lines. The recurrent parent genome recovery ranged from 72 to 93.8 %. ICF2_Zaa/556/SARC-P6 had the highest recurrent parent genome and the least heterozygosity among the five improved lines. The five pyramided lines showed superior resistance under artificial aphid infestation as compared to the two donor parents with damage scores ranging from 2.0 to 2.3. On the field, however, there were no significant differences between the pyramided lines and their recurrent parent for all the agronomic traits measured except for grain yield. The pyramided lines do not only stand the chance of being released as new varieties but are also valuable genetic resources for other breeding programs that seek to improve cowpea for aphid resistance.

The potential of cowpea (Vigna unguiculata [L] Walp) to contribute to food security and livelihood sustenance of sub-Sahara Africans is constantly threatened by many biotic and abiotic stresses that are aggravated by climate change. To address these threats, cowpea breeding programs in the subregion prioritize climate-resilience traits and resistance to biotic stresses. However, before successful trait discovery and implementation, it is essential to characterize diversity and population structure of cowpea germplasm. To test the hypothesis that assembled cowpea germplasm exhibits limited and narrow genetic diversity with a well-defined population structure, we assessed the level of genetic variability and characterized the population structure of 188 cowpea genotypes using 5147 Single Nucleotide Polymorphism (SNP) markers. The structure results revealed five major genetic groups with moderate levels of genetic diversity and an admixture level of 17 %. Discriminant analysis and phylogenetic analysis supported this finding, indicating the presence of distinct groups within the cowpea population. The analysis of molecular variance (AMOVA) showed 27 % among population variance, 64 % within-population variance, and 9 % within individual variance. While considering the origin, the AMOVA showed 16 % among population variance, 75 % among individual variance, and 9 % within individual variance. This study provides valuable insights for future cowpea improvement programs by facilitating the selection of suitable progenitors for population development, and contributing in the conservation of cowpea genetic resources. Addressing these challenges and enhancing cowpea's diversity and resilience are crucial steps towards ensuring food security and sustainable livelihoods in sub-Saharan Africa.

The economic return for peanut (Arachis hypogaea L.) in Ghana is often low due to limitations in the availability of inputs or their adoption, which are needed to optimize yield. Six experiments were conducted in Ghana in 2020 and 2021 to determine the impact of planting date, cultivar, fertilization, pest management practices, and harvest date on peanut yield, financial return, and pest reaction. A wide range of interactions among these treatment factors were often observed for infestations of aphids (Aphis gossypii Glover); groundnut rosette disease (Umbravirus: Tombusviridaee); millipedes (Peridontopyge spp.); white grubs (Schyzonicha spp.); wireworms (Conoderus spp.); termites (Microtermes and Odontotermes spp.); canopy defoliation as a result of early leaf spot disease caused by Passalora arachidicola (Hori) and late leaf spot caused by Nothopassalora personata (Berk. and M. A. Curtis); and the scarification and boring of pods caused by arthropod feeding. Pod yield and economic return increased for the cultivar Chitaochi and Sarinut 2 when fertilizer was applied and when fertilizer was applied at early, mid-, and late planting dates. Pod yield and economic return increased when a combination of locally derived potassium soaps was used for aphid suppression and one additional hand weeding was used in the improved pest management practice compared with the traditional practice without these inputs. Pearson correlations for yield and economic return were negatively correlated for all pests and damage caused by pests. The results from these experiments can be used by farmers and their advisors to develop production packages for peanut production in Ghana.

Maize yield losses due to fall armyworm (FAW) infestation is in the range of 22–67%, amounting to millions of US dollars in sub-Saharan Africa (SSA). Identifying new sources of maize genotypes with resistance to insects and a better understanding of resistance mechanisms have opened the avenue for the exploration of host-plant resistance (HPR). The present study was carried out to assess the resistance of maize inbred lines and hybrids to FAW foliar feeding damage through natural and artificial screening. Thirty-five (35) maize inbred lines obtained from the International Maize and Wheat Improvement center (CIMMYT) and the United State Department of Agriculture – Agricultural Research Services (USDA–ARS) were screened for fall armyworm resistance in Ghana in 2019. In addition, sixty (60) single-cross hybrids and twenty (20) double-crosses developed from 17 desirable inbred lines were evaluated for resistance to fall armyworm using artificial and natural infestations in 2020 and 2021. Significant differences were recorded among the inbred lines, F1 hybrids, and the double-crosses. The cluster and principal component analysis classified the thirty-five inbred lines into four groups suggesting the presence of wide variability. Hybrids (CML343*CML 346)//(CML124*MP 713), (MP713*MP705)//(CML123*MP713), (CML331*MP701)//(MP702*MP705), (CML330*MP702)//(CML123*MP706), (CML122*MP713)//(CML330*MP701), (OBT*MP708)//(MP713*MP705),MP704*CML122)//(CML123*MP713), (CML123*MP708)//(CML122*MP713) and (CML330*MP701)//(MP713*MP705) were found to be promising. These hybrids should be recommended for further testing and commercialization in SSA.

The study was carried out to determine the nutritional and anti-nutritional composition of taro genotypes and also determine the phenotypic plasticity of the genotypes in two agro ecological zones in Ghana. The towns and zones were Bunso in the semi deciduous forest (an upland) and Tano Dumasi in the forest savannah transition agro-ecological (a waterlogged area) zone in the Eastern and Ashanti regions respectively.Two (2) freshly harvested corms of each genotype from each location were assessed for their nutritional (moisture, protein, carbohydrate, ash and fat) and anti-nutritional (phytate, oxalate and tannin) composition Data collected were subjected to analysis of variance and AMMI analysis using GenStat 12 edition to assess the effect of genotype, environment and their interaction on the traits studied. Phenotypic plasticity for the genotypes and the traits studied was also calculated. Pearson correlation was also conducted to assess the relationship between the traits studied. There were significant differences among the genotypes for nutrient and anti-nutrient composition except for percentage fat, indicating enough genetic variability among the genotypes, giving room for good selection progress for development of taro varieties. A higher magnitude of the environment over genotype and genotype by environment interaction observed indicates the influence of environment in the expression of the nutritional and anti-nutritional traits. Observed varied phenotypic plasticity among the genotypes for the nutrient and anti-nutrients composition also indicates varied adaptation of the genotypes to the environment. Genotypes BL/SM/115, CE/MAL/32 and CE/IND/16 and hybrids KAO19 × CE/MAL/32 and CE/IND/16×KAO19, CE/IND/16 × BL/SM/10, and CE/IND/16 × BL/SM/115 which recorded high nutrients and low anti-nutrients content and were stable across the environments can be released to farmers for cultivation. They could also be included in breeding programs for the development of enhanced nutritional quality of taro in Ghana.

Antigen-coated plate enzyme-linked immunosorbent assay (ACP-ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) were used to detect the presence and seed transmissibility of bean common mosaic virus-blackeye cowpea mosaic (BCMV-BICM) in farm- retained cowpea seed lots obtained from 46 locations, including markets and farms in major cowpea growing areas in the Ashanti and Brong Ahafo regions of Ghana. In the growout tests, virus symptomatic plants were observed in seedlings of 19 of the 46 seed lots tested under insect-proof screen-house conditions. All the symptomatic plants tested positive to polyclonal antiserum raised against BCMV-BICM in ACP-ELISA. The seed transmission rates based on symptoms ranged from 0 to 37.8 %. RT-PCR with primer pair designed to amplify the potyvirus Cylindrical Inclusion (CI) region resulted in an expected 720 bp DNA segment in 19 seed lots as a further confirmation of virus in the seed lots. The remaining 27 lots were asymptomatic and tested negative to BCMV-BlCM in both ACP-ELISA and RTPCR. The findings of this study revealed seed as the source of primary inoculum in the farmers’ fields and may aid in the implementation of control strategies such as discouraging farmers from retaining their own seeds for subsequent sowing and encouraging them to take appropriate measures in obtaining virus-free cowpea seeds from other sources.

The nature of gene action controlling agronomic traits enables plant breeders to execute a successful crop improvement programme. To elucidate the type of gene action governing the key earliness related traits in cowpea, seven populations of the six basic generations, viz; P1, P2, F1, F2, BC1 and BC2 were developed by crossing three extra-early and three early-to-medium maturing parental lines. Each of the populations were sowed in Randomised Complete Block Design, in the experimental field of Council for Scientific and Industrial Research (CSIR)-Savana Agricultural Research Institute Manga, Ghana. Observations were made on days to first flower appearance (DFFA) and days to 95% pod maturity (DNPM). The results indicated that the epistatic gene interaction for DFFA in most of the crosses was duplicate epistasis between dominant decreasers. For DNPM, duplicate epistasis between dominant increasers was found. Only Kirkhouse-Benga × CB27 revealed complementary epistasis between dominant decreasers for both traits. Among the significant epistasis terms re-estimated using perfect fit procedure, the χ2 values were not applicable in any of the crosses, indicating the inadequacy of the six-parameter model of digenic epistasis. Therefore, trigenic or other high-order epistasis could be responsible for the inheritance of the traits evaluated. This implies that improvement of earliness in cowpea could be achieved through hybridization method, followed by selection of promising recombinants in later generation, for crosses governed by duplicate epistasis. Complementary epistasis detected for one of the crosses is desirable and would be beneficial in the development of early duration varieties, where selection could be done at early generation. The preponderance of partial-dominance, over-dominance of earliness over late maturity, and significant negative heterosis and heterobeltiosis observed for DFFA and DNPM indicated that the developed of short duration cowpea cultivars would be efficient. The genetics of the three most popular extra-early maturing cowpea genotypes reported in this study could be exploited by breeders to develop extra-early duration varieties.

Global climate change is expected to further intensify the already harsh conditions in the dry savannah ecological zones of sub-Saharan Africa, posing serious threats to food and income security of millions of smallholder farmers. Breeding cowpea for improved earliness could help minimize this risk, by ensuring that the crops complete their lifecycle before the cessation of rainfall. In this study, we crossed two sets of cowpea lines showing contrasting phenotypes for earliness in terms of days to 50% flowering (DFF). One set of the lines comprised three extra-early parents (viz.: Sanzi-Nya, Tobonaa and CB27, 30–35 DFF), and the other set consisted of three early-to-medium maturity lines (viz.: Kirkhouse-Benga, Wang-Kae and Padi-Tuya, 42–45 DFF). The derived crosses and their parents were evaluated for key earliness-related traits at Nyankpala and Manga sites of CSIR-Savanna Agricultural Research Institute (SARI), Ghana. To unravel the genetic control of measured traits, we compared the appropriateness of Chi-square goodness of fit tests using classical Mendelian ratios, and frequency distribution (histogram)-related statistics such as skewness and kurtosis. The Chi-square test suggested a single dominant gene mode of inheritance for earliness, whereas the quantitative methods implicated duplicate epistasis and complementary epistatic gene actions. Our results show that coercing segregating lines to fit into classical Mendelian ratios to determine the genetic control of earliness could be misleading, due to its subjectivity. Thus, the genetic control of earliness in cowpea is governed by complementary and duplicate epistasis. The most applicable breeding approach for traits influenced by duplicate epitasis is selection of desirable recombinants from segregating populations developed from bi-parental crosses. Complementary epitasis, as found in the Wang-Kae × CB27 cross, could be exploited in developing improved extra-early lines through backcrossing. Heritability and genetic advance estimates were high for days to first flower appearance (DFFA) and days to 95 % pod maturity (DNPM) in the Padi-Tuya × CB27 and Kirkhouse-Benga x CB27 crosses, indicating that breeding for extra-earliness is feasible. CB27 could be a good donor for introgression of earliness into medium to late maturing improved cowpea varieties, because crosses developed from it had high heritability and genetic advance estimates.

Forty common bean accessions of multiple genetic background trait attribution regarding drought tolerance were selected based on mean yield performance from an earlier field test evaluation conducted using augmented RCBD. The various bean genotypes were further evaluated with phosphorus and water treatment interactions at two different levels for each factor. The experiment was conducted in a 2 × 2 × 40 factorial using RCBD with three replications under screen-house conditions at the CSIR-Crops Research Institute, Kumasi-Ghana. The objective was to select drought- and low phosphorus-tolerant common bean genotypes; which are suitable for tropical climatic conditions. The results showed that common bean with drought and heat trait tolerance survived, developed flowers and podded with seeds to physiological maturity, whilst genotypes with no heat trait tolerance had impaired reproductive structural development and growth disruption; thus, flowers could not develop into pods with seeds. This reproductive developmental anomaly was due to prevailing average daytime and nighttime high temperatures of 35.45 °C and 29.95 °C, respectively, recorded during the growth period, which reduced pollen fertility. Among the 478 experimental bean plants (two plants were missing) analyzed, 141 (29.5%) did not flower, 168 (35.18%) had their pods dropped whilst 99 (20.7%) podded with seeds to achieve physiological maturity. The podded-seed bean genotypes were of the SEF-line pedigrees, which were shown to be heat and drought-tolerant. Meanwhile, bean accessions with SMC, SMN and SMR code prefixes did not pod into seed despite possessing drought-tolerant traits. The effects of interactions between phosphorus and water treatments on the root characteristics of drought-tolerant common bean were as follows: root length, root surface area, average root diameter and root volume growth extensions doubled dimensionally under optimum conditions (P2W2) compared to stressed conditions (P1W1). The results from the present study identified four SEF-bean genotypes, namely, SEF15, SEF 47, SEF 60 and SEF 62, as superior yield performers, even under low soil phosphorus and in extreme high temperature conditions. Therefore, breeding for the selection of drought- and low-P-tolerant common bean for tropical agro-ecological environments must also consider concomitant heat stress tolerance.

Abstract Availability of multiple-stress tolerant maize is critical for improvement in maize production in West and Central Africa (WCA). A study was carried out to (i) assess a set of inbred lines for combining ability under stressed and optimal conditions, (ii) determine the performance of the testcrosses under different conditions, and (iii) identify outstanding hybrids across the conditions. Two hundred and five testcrosses were planted with five hybrid checks under Striga-infested, low soil nitrogen, drought and optimal conditions between 2015 and 2016 in Nigeria. The grain yield inheritance under optimal condition was largely regulated by additive gene effect whereas non-additive gene effects largely regulated grain yield under the three stresses. Four of the inbreds had significant positive general combining ability effects each under low N and drought, and three under Striga infestation for grain yield. The inbreds could be vital sources of beneficial alleles for development and improvement of tropical yellow maize hybrids and populations. Hybrids TZEI 443 x ENT 13 and TZEI 462 x TZEI 10 were high yielding and stable; they out-performed the three early maturing released hybrids in WCA. The new hybrids should be extensively assessed and released in the sub-region to improve food security.

Anther indehiscence in certain wide crosses combines male sterility with stigma exertion, a phenomenon that is desirable for hybrid rice seed production. This study sought to identify chromosomal region(s) that combine anther indehiscence with exerted stigmas. A mapping population consisting of 189 BC1F1 plants was derived from a cross between CRI-48 and Jasmine 85 and backcrossing the resulting F1 to Jasmine 85. Contrary to the three complementary genes mode of inheritance reported earlier, a single locus (AI6-1) was mapped on chromosome 6 at 27.4 cM for anther indehiscence with exerted stigmas through a mixed model-based composite interval mapping (MCIM). This locus was flanked by two single nucleotide polymorphism (SNP) markers, K_ID6002884 and K_ID6003341 within a range of 23.1–28.9 cM. The allele at the locus was contributed by the CRI-48 parent which has Oryza glaberrima ancestry. This locus is suggested to control anther indehiscence and stigma exertion through pleiotropic gene action or cluster of genes.

Twenty-two open-pollinated varieties (OPVs) of pearl millet (Pennisetum glaucum) genotypes were tested in two locations for three seasons in Ghana to estimate the magnitude of genetic variability, heritability, and stability for grain yield and related traits and grain micronutrients among the varieties. General analysis of variance within and across locations and years revealed very highly significant variability (p

Cassava (Manihot esculenta Crantz) is an important industrial and staple crop due to its high starch content, low input requirement, and resilience which makes it an ideal crop for sustainable agricultural systems and marginal lands in the tropics. However, the lack of genomic information on local genetic resources has impeded efficient conservation and improvement of the crop and the exploration of its full agronomic and breeding potential. This work was carried out to obtain information on population structure and extent of genetic variability among some local landraces conserved at the Plant Genetic Resources Research Institute, Ghana and exotic cassava accessions with Diversity Array Technology based SilicoDArT and SNP markers to infer how the relatedness in the genetic materials can be used to enhance germplasm curation and future breeding efforts. A total of 10521 SilicoDArT and 10808 SNP markers were used with varying polymorphic information content (PIC) values. The average PIC was 0.36 and 0.28 for the SilicoDArT and SNPs respectively. Population structure and average linkage hierarchical clustering based on SNPs revealed two distinct subpopulations and a large number of admixtures. Both DArT platforms identified 22 landraces as potential duplicates based on Gower's genetic dissimilarity. The expected heterozygosity which defines the genetic variation within each subpopulation was 0.008 for subpop1 which were mainly landraces and 0.391 for subpop2 indicating the homogeneous and admixture nature of the two subpopulations. Further analysis upon removal of the duplicates increased the expected heterozygosity of subpop1 from 0.008 to 0.357. A mantel test indicated strong interdependence (r = 0.970; P < 0.001) between SilicoDArT and DArTSeq SNP genotypic data suggesting both marker platforms as a robust system for genomic studies in cassava. These findings provide important information for efficient ex-situ conservation of cassava, future heterosis breeding, and marker-assisted selection (MAS) to enhance cassava improvement.

Development, testing and selection of superior inbred lines is crucial for the success of a hybrid program targeting Striga-infested and low soil nitrogen (low-N) environments. The practical value of inbred lines is determined by multiple traits, most of which are inter-dependent. The main objective of this study was to identify early maturing inbred lines based on multiple traits under optimal, low-N and Striga-infested environments for hybrid development and population improvement. One hundred early maturing inbred lines were evaluated under artificial Striga-infestation, low-N and optimal growing environments for two years at Kwadaso and Nyankpala in Ghana. The inbred lines exhibited high levels of genetic variability for grain yield and other agronomic traits desirable for Striga resistance and low-N tolerance. Under optimal growing conditions, days to silking (DS), ears per plot (EHARV) and days to anthesis (DA) had high direct effects on grain yield (GYLD). Days to silking and ears per plant (EPP) had the highest positive direct effects on GYLD, while DA had the highest negative direct effect on grain yield in low-N environments. Under Striga-infestation, the highest negative direct effect on GYLD was obtained with EASP. All the measured traits previously identified to have direct influence on grain yield were associated with it and could be used for indirect selection for improved grain yield under the contrasting environments. Forty-eight of the 100 inbred lines studied were identified as low-N tolerant and forty-nine as Striga resistant.

Information on genetic diversity and population structure are very important in any breeding programme for the improvement of traits of interest and the development of outstanding products for commercialization. In the present study, we assessed the genetic diversity of 94 early-maturing white and yellow tropical maize inbred lines using single nucleotide polymorphism (SNP) markers. The larger number of SNP markers used in this study allowed a clearer inference of the population structure of the 94 inbred lines. Cluster analysis resolved the inbred lines into different clusters based on their pedigree, selection history and endosperm colour. However, three heterotic groups were revealed by population structure analysis, but additional field evaluation could be more informative to confirm the heterotic groups identified. Nevertheless, wide genetic variability existed among the inbred lines making them unique with the potential to contribute new beneficial alleles to maize breeding programmes in the tropics, especially in the West and Central Africa (WCA) sub-region.

Despite its importance in providing income and food for smallholder farmers, fodder for livestock, and improving soil fertility through biological nitrogen fixation, groundnut yields are lowest on farmers’ fields in Sub-Saharan Africa due to biotic and abiotic constraints. Foliar fungal diseases account for over 80% reduction in groundnut productivity in some parts of Ghana. Unfortunately, chemical control of these foliar diseases has not yielded the desired results. Meanwhile, advances in phenotyping for disease tolerance in other crops have established a strong relationship between stay-green trait and foliar disease tolerance. However, this relationship has not been explored in groundnut. This study was designed to determine the genetic control of the stay-green trait and its relationship with leaf spot disease severity in groundnut. Twenty-five advanced groundnut breeding lines with varying degrees of tolerance for leaf spot tolerance were evaluated under diseased and disease-free conditions, after which four were selected for genetic studies. Results showed significant (p

Hybrid rice technology is one of the promising, sustainable, and proven technologies for increasing rice production and productivity with a yield advantage of 15–30% over modern inbred varieties. The potential of hybrid rice has so far not been exploited in Ghana. This study was undertaken to evaluate the yield potential, reaction to diseases, and physical grain attributes of some introduced hybrids. The trials were laid out in a randomized complete block design (RCBD) with three replicates across three locations. Data were taken on grain yield, yield components, reaction to diseases, and grain physical characteristics. Four promising hybrids (SWARNA 2, ARGH 1501, ARGH 1502, and ARGH 1503) with a mean yield advantage of 15–20.8% over the best inbred check “AgraRice” were identified. With few exceptions, the hybrids were broadly adapted and had adequate resistance to blast and bacterial leaf blight. Most of the test hybrids had long slender grains which make them acceptable to the Ghanaian market but lacked aroma.

A field experiment was conducted at Savanna Agricultural Research Institute in 2015 cropping season to examine the inheritance of early maturity among an extra-early maturing landrace Sanzi and a medium maturing variety Padi-Tuya and their progenies. The results indicated highly significant (P0.05) were observed between F1 and RF1, implying absence of maternal effect. The segregation ratio in the F2 population for early and medium maturity fitted into the ratio 3 : 1, indicating single dominant gene mode of inheritance. Significant positive correlations were found between DNPM, DFFI, DFF, and DFPM; hence selection criteria to improve early maturity of cowpea should focus on these traits. Grain yield also had significant positive correlations with maturity indices indicating high grain yield is associated with late maturity; therefore, high grain yield should be considered alongside early maturity when selecting progenies for earliness.