School of Biological Sciences
Permanent URI for this communityhttp://197.255.125.131:4000/handle/123456789/4743
Browse
7 results
Search Results
Item Phenotypic Characterization Of Cowpea.(University Of Ghana, 2021-12) Arthur, K.S.Cowpea is indigenous to the African continent and is usually grown for its leaves and grain in different countries of the world. The objective of this study was to evaluate cowpea accessions using morphological descriptors and phytochemical analysis to identify cowpea accessions with a more specific traits that could be used by breeders. Phenotypic characterization of twenty-seven (27) cowpea accessions which consist of twenty-four (24) from the Department of Plant and Environmental Biology as test material and three (3) others, namely ‘Asontem’, ‘Wang Kae’ and ‘Kirkhouse’ which were used as checks, was undertaken. The cowpea population was evaluated based on agro-morphological traits (quantitative and qualitative) and phytochemical traits. STATA version 15.0 was used to carry out descriptive, multivariate analyses whiles ‘R’ software was used for genetic component analysis to determine the extent of variation. Phytochemical analysis was carried out to study the polyphenolic and amino acid contents of the cowpea seeds using standard methods and protocols. Polyphenolic compounds were determined using a spectrometer and amino acid contents were determined with assistance from Ghana Standard Authority. In the morphological qualitative traits studied, erect cowpea plants showed the highest distribution for growth habit with frequencies of 91% in the test material and 84.17% in the entire population. The pale tan pod colour recorded the highest frequency of 62.58% in the entire population, similarly, the pale tan with frequencies 65.48% and 62.58% were the highest frequency in both control and test material respectively. The white seed coat colour had the highest frequency of 66.11%in the entire population as well. The chi-square test of association between qualitative traits showed 86 significant associations in the test materials, with growth habit having the highest signicant associations with leaf size (χ² = 220.84, P = 0.000), whereas the control showed 78 significant associations. The overall population exhibited 86 significant associations, with growth habit having the highest positive significant association with terminal leaflet shape (χ² = 243.87, P = 0.000). The phenolic compound had higher mean concentration in the controls than the test material, however higher mean concentration of amino acid was obatined in the test materials than in the control. A total of 145, 113 and 123 significant pairwise correlations were observed in the control, test materials, and entire population respectively for all quantitative traits. In the test material vanillic acid was highly correlated with gallic acid (r = 1.00) and p-coumaric acid (r = 1.00). Principal component analysis showed that, the first seven principal components in the morphological traits accounted for a total variability of 84.00% in the control, while nine principal components explained 81.00% of the total variation in the test material. On the other hand the first five principal components in the phytochemical traits accounted for 100%, 100% and 83% of the total variation in the control, test materials and entire population respectively. The biplot showed that the relationships among accessions and morphological, phytochemical and all traits explained 33% and 51% of the total variance respectively. The cluster analysis for the morphological traits revealed five distinct clusters. Genotypes named Asontem, T3, T5, T22 were grouped in a single cluster and were characterized by least days to germination (3.58), highest mean number of branches (4.93), least mean number of leaves (41.26), highest mean number of nodes (9.83), least mean leaflet width (3.69), the highest mean days to first flowering, least mean number of pods per peduncle (2.81), least average pod width (0.80), highest mean number of pods per plant (49.50), the highest average number of seed per pod (15.97), highest mean days to first matured pod (42.01), highest mean number of seeds per plants (795.75) compared to other clusters. These genotypes could be used as parents in genetic improvement programs aiming to increase yield. Biometrical analysis revealed that the phenotypic variance (σ2 p) was higher than the genotypic variance (σ2 g) regarding all morphological traits evaluated. The number of seeds per plant reported the highest genotypic (80841.20) and phenotypic (107162.90) variance while the lowest genotypic (0.09) and phenotypic (0.69) value was recorded by the days to germination and average seed thickness respectively. Low (≤20%) heritability broad sense values were observed in all the morphological traits and ranged from 0.33% for days to germination to 0.99% for seed weight.Item Evaluation Of Yield And Sub-Yield Components Of Cowpea (Vigna Unguiculata (L) Walp) Accessions(University Of Ghana, 2021-12) Mensah, K.H.One hundred and eight cowpea accessions were evaluated for yield and sub-yield components at the Department of Plant and Environmental Biology. They consisted of 60 F2 segregating, 44 accessions as test materials and 4 controls. The controls were Asontem Wang Kae, Padituya and Kirkhouse from CSIR-SARI. Data collected comprised of morphological and phytochemical traits. Descriptive, multivariate and genetic component analyses were carried out to evaluate the extent of variation. Rank summation index and contrast analysis were performed to select the best performing accessions. For the morphological traits studied, semierect growth habit with frequencies of 64.78%, 43.75% and 51.45% which occurred in the test materials, controls and the entire population. The majority of the accessions in the test materials exhibited red seed coat colour (19.59%) whereas in the controls most of the accession showed cream seed coat (50%). Overall, the majority of the accessions exhibited cream seed coat colour with a frequency of 35.35%. The chi-square test of association between qualitative traits showed was 125 significant associations in the test materials whereas the controls only showed 3 significant associations. The overall population exhibited 162 significant associations. In the multiple correspondence analysis (MCA) terminal leaf shape, growth habit, pod curvature and raceme position mostly led to variation in the first dimension which accounted for inertia of 51.40%. Thirteen farmer and consumer-preferred traits were used in the MCA plot. Asontem, UG8 and UG30 had a close relationship with similar phenotypic classes in the first quadrant of the MCA plot. UG1 and UG81 were outliers and had a distant relationship with majority of the phenotypic classes of the selected traits. The test materials had a significantly higher mean than the controls for the following traits; number of pods per plant, number of locules, seed weight and seed yield but lower than the controls for the following traits; days to first flower, days to 50% germination, days to first mature pod and days to 50% mature pod. Furthermore, the test materials were significantly higher in mean concentration for the following amino acids; gallic acid and vanillic acid, glycine, l-histidine, l-aspartic acid, l-valine and l-methionine. A total of 191, 537 and 413 significant pairwise correlations were observed in the test materials, controls and entire population respectively for all quantitative traits. The multiple regression analysis revealed that the underlying determinant of yield was most influenced by yield and yieldrelated components in the test materials and controls with contributions of 100% and 36.67% respectively. Phytochemical traits made the highest contribution of 25.95% to influencing variation in yield for the entire population. The first six principal components in the morphological traits accounted for a total variability of 47.17%, 55.40 %, 42.99% in the test materials, controls and entire population respectively. The first three principal components in the phytochemical traits accounted for a total variability of 51.81%, 100 %, 53.14% of the total variation in the test materials, controls and entire population respectively. The biplot showed that the relationships among accessions and morphological, phytochemical and all traits explained 46.63% and 99.49 and 94.48 % of the total variance respectively. The canonical discriminant analysis grouped against yield showed that the first CV accounted for 17.19% and 40.82% for the respective morphological and phytochemical traits. The cluster analysis based on morphological and phytochemical traits clustered the 108 accessions into 7 and 6 major groups respectively. The genetic component studies showed that seed yield had a high genotypic (63.1%) and phenotypic (243.8%) variances but low heritability of 18.41% while phytochemical traits had high GCV (>20), PCVs (>20) and heritability (>80%). Based on the lowest RSI scores, the 10 best performing accessions with high yield potential among the population evaluated were UG84, UG24, UG44, UG69, UG47, UG14, UG70, UG66, UG36, UG102 . The marginal analysis revealed that no accession was significantly higher in yield than the overall mean. However, it confirmed cluster grouping of accessions based on trait similarities and dissimilarities.Item Susceptibility Of Five Cowpea Varieties To Field And Storage Insect Pests(University Of Ghana, 2021-09) Baffoe- Ansah, J.Cowpea, Vigna unguiculata, is a popular food crop in the tropics and subtropics. The crop is particularly susceptible to pests and diseases, limiting its yield. Cowpea cultivars that are resistant to pests in the field and in storage are becoming increasingly significant. Five improved cowpea varieties were screened (‘Asontem’, ‘Golinga’, Kirk house, ‘Padi Tuya’ and ‘Wang Kae’) for their susceptibility to field and storage insect pests. The field experiment was laid out in a Randomized Complete Block Design with five treatments and four replicates. The insect pests encountered were identified and recorded. Mean yield parameters such as number of pods per plant, weight of pods per plant, length of pod, number of seeds per pod, number of loci per pod, seed weight per pod, 100-seed weight, and total yield were assessed. In the minor season, ‘Golinga’ recorded the highest number of pods per plant, while ‘Padi Tuya’ had the least number of pods per plant. Meanwhile, ‘Asontem’ recorded the highest yield of 71.7 g in the minor season, while ‘Padi Tuya’ recorded the least value of 60.4 g. In the major season, ‘Wang Kae’ recorded the highest number of pods per plant, while ‘Padi Tuya’ recorded the least number of pods per plant. ‘Asontem’ again recorded the highest total yield of 74.1 g while ‘Padi Tuya’ recorded the least mean total yield of 59.2 g. Correlation between insect infestations and yield of the varieties in the field was determined. Aphis craccivora infestation was negatively correlated (r = - 0.2368, p > 0.05) with total yield in the major season. Megalurothrips sjostedti infestation was negatively correlated with the total yield (r = - 0.0784, P > 0.005) in the major season, and was also negatively correlated with the total yield (r = - 0.4232, P > 0.01) in the minor season. Maruca vitrata infestation was positively correlated with the total yield (r = 0.0636), P > 0.05) in the major season, while it was negatively correlated with total yield (r = - 0.3767, P >0.01) in the minor season. The laboratory experiment was laid out in a Completely Randomized Block Design with five treatments and three replicates. There was significant repellence of Callosobruchus maculatus by the different concentrations (1g/mL and 2g/mL) of the five cowpea extracts. All five cowpea varieties recorded C. maculatus mortalities after 4 days of introducing the adult insects onto the seeds. The five cowpea varieties recorded some levels of damage for the six-week period after introduction of C. maculatus. C. maculatus infestations and seed weight during storage were determined after the six-week period. The median development period of the C. maculatus in the five cowpea varieties ranged from 17 to 28 days, with four out of the five varieties (‘Asontem’, ‘Golinga’, ‘Kirkhouse’ and ‘Wang Kae’) classified as moderately resistant to insect infestation, and one (‘Padi Tuya’) classified as susceptible to insect infestation. Qualitative and quantitative phytochemical analysis on the cowpea varieties confirmed the presence of different levels of phenols, flavonoids, tannins, and alkaloids.Item Linkage Disequilibrium And Association Mapping Of Cowpea (Vigna Unguiculata (L.) Walp) Quantitative Traits(University of Ghana, 2020-10) Ajara, S.A genome-wide association study (GWAS) was conducted using 187 cowpea germplasm to study linkage disequilibrium and association mapping of some cowpea quantitative traits. All the accessions with the exception of two which were obtained from the Department of Plant and Environmental Biology, were assembled from International Institute of Tropical Agriculture Germplasm Resources Information Centre. These accessions comprised 94 cultivated types and 93 wild relatives. Data on morpho-agronomic traits were collected using the Cowpea Descriptor by the International Board for Plant Genetic Resources. A total of 32 morpho-agronomic traits and 46 SNPs markers were assessed. Ethanol extracts of pulverized dried cowpea seeds were used to determine the amino acid concentrations. Data analysis involved descriptive statistics, Pearson’s correlation, principal component analysis (PCA), cluster analysis, Nei’s genetic diversity of subpopulations, likelihood ratio test for Hardy Weinberg equilibrium, F statistics and gene flow, population structure and genetic distance analysis. High variation was observed in the morpho-agronomic traits. A total of one hundred and thirty-six (136) significant pairwise correlations were observed in the quantitative traits. Out of the forty-six (46) SNPs markers, forty-three (43) were polymorphic. Means for the quantitative traits studied were as follows: days to 50% germination was 3.93±0.26 days. Mean days to first leaf stage was 12.40±0.24 days. Mean chlorophyll content was 1.44±0.02 mg/liter. Mean days to 50% flowering was 65.97±1.97 days. Mean number of flowers per plant was 8.95±0.55 flowers. Mean peduncle length per plant was 13.39±0.45 cm. Mean number of pods per peduncle was 1.97±0.01 pods. Mean days to 50% pod maturation was 81.86±1.97 days. Mean number of pod per plant was 7.09±0.54 pods. Mean pod length per plant was 11.53±0.28 cm. Mean average seed per pod was 9.86±0.24 seeds. Mean 20 seed weight was 1.5580±0.07 grams. Mean seed yield per plant was 70.31±5.65 seeds. Mean seed abortion rate per plant was 2.14±0.08 percent. All the 19 amino acids analyzed for the seed quality traits were present in the accessions, except L-Cysteine which was beyond detection. However, some accessions recorded 0.00 for Iso-Leucine and Trans-4-Hydroxyl-Proline. Mean concentrations for the amino acids was generally low in the wild relatives. It ranged between 21623.03±5299.45 x 10-5 ppm (L-Tryptophan) to 17.52±5.36 x 10-5 ppm (L-Methionine) while that for the cultivars varied from 3953909.00±7143.39 x 10-5 ppm (L-Tryptophan) to 18266.33±2524.18 x 10-5 ppm (L-Methionine). Mean Nei’s genetic diversity for the overall population was 0.3001, mean Wright’s Fixation coefficient for inbreeding (FIS) was 0.8935, mean degree of differentiation within population (inbreeding at different level) (FIT)was 0.9143, mean degree of genetic differentiation (FST) was 0.1952, mean gene flow (Nm) was 1.0309, mean observed heterozygosity was 0.0242 and mean frequency of cross pollination (C) was 0.0805. Analysis of population structure grouped the cowpea accessions into two clusters. Proportion of membership for cluster 1 was 0.551 and that for cluster 2 was 0.449. The mean FST value for cluster 1 was 0.064 and that for cluster 2 was 0.048. Intra chromosomal linkage disequilibrium estimate for SNPs loci revealed 12.64% and 15.38% at the threshold level of r2 ≥ 0.1 and r2 ≥ 0.05 respectively. The largest LD block observed was 25.0 bp between SNPs markers 6904_1061 and 9815_2051 at correlation co-efficient measure of variability between two loci (r2) of 0.10 and the difference between the gamete frequencies at two different loci (D’) of 0.89. Partial linkage disequilibrium decay was observed from a graph of r2 values of LD (between 0.0 and 0.75) against map distance ranging from 0.0 to 38.75 cM. Significant marker-trait associations were identified with very high potential for exploitation in marker-assisted breeding for the important traits in cowpea. Number of flowers per plant, mean peduncle length, number of pods per peduncle, number of pods per plant, seed yield per plant and DL-Beta phenyl-Alanine were associated with different SNPs markers at 5 cM map distance while 20 seed weight, D-Proline, Iso-Luecine, L-Histidine and L-Serine were associated with different SNP markers at 0.0 cM map distance.Item Genetical Linkage In The Cowpea (Vigna Unguiculata (L) Walp(University of Ghana, 1991-10) Asante, E.I.K.Item Identification of Resistance Cultivars of Cowpea [Vigna unguiculata (L.) Walp] to Flower Thrips (Megalurothrips sjostedti Trybom) among Benin Germplasm(University Of Ghana, 2019-07) Tossou, T.H.Cowpea [Vigna ungriculata (L.) Walp] is a leguminous plant and is one of the staple crops much cultivated in Benin and neighboring countries and in Africa as a whole. Cowpea production is hindered by many biotic and abiotic factors, with the flower bud Thrips, Megalurothrips sjostedti (Trybom) being the most damaging pest at flowering stage causing yield losses of 20 to 80%. Control of flower bud thrips in the field is difficult due to its cryptic behaviour. Thus, the combination of control measures in addition to the use of resistant lines is promising. However, there is insufficient data on Benin cowpea germplasm resistance to flower bud thrips. Therefore, this study was aimed at identifying resistant cultivars to thrips among Benin germplasm and provide lines for breeding programs for eventual improvement of cowpea to the flower bud thrips in Benin. In order to identify resistant lines, the most damaging local population of flower bud thrips was selected among existing diversity, and cowpea accessions from greenhouses and the field screened for the trials. Flower bud thrips were collected from seven locations where cowpea is produced within two agro-ecological zones in Benin. The varying populations were reared, characterized on Sewe and vita7 (susceptible and resistant checks, respectively), and used to infest genotypes in the greenhouse. In greenhouse, 48 accessions were evaluated using CRD with three replicates. A total number of 25-30 nymphs at the fifth larval stage (6-7 days after hatching) were placed on single experimental plants. Data from the thrips damage and yield parameters were subject to variance analysis. Results showed that there were significant differences among accessions in terms of thrips damage and cowpea yield. Fourteen accessions (IT07K-243-1-10 (1), Sèwé (2), Sanzibanili (2), Awlétchi (3), Awonlignikoun (3), Gléssissaffodo (3), IT83S-742-2 (3), IT86D-888 (3), Kpègnikoun (3), Kpodjiguèguè (3), Kumassi (3), Moussa (3), Nontché-Wagbèhami (3) and Tiligré (3) were identified to be resistant (showing damage scores of 1 to 3) among the 48 tested, while the rest of the accessions presented high thrips damage scores (5-9). In order to evaluate the effect of environment on thrips damages, the same accessions were planted in three different locations, where cowpea is produced in Benin. The accessions were planted in an Alpha lattice design with three replications. Susceptible check (Vita7) was used as spreader rows surrounding each replication. Data were collected on thrips damage, thrips population per genotype at weekly intervals for four weeks, based on the commonly used scoring scale (1-9). Thrips damage scores and grain yield were subjected to Additive Main effects and Multiplicative Interaction (AMMI) and Genotype plus Genotype by Environment (GGE) biplot analyses. Genotype and genotype by environment interactions effects were not significant. A significant (P<0.001) difference was found between the accessions for thrips damage, adults and larvae of flower bud thrips on cowpea. Four accessions (IT84S-2246-4, Mawougbadonou, IT07K318-33, and IT93K-452-1) were found to be the most resistant and stable lines across locations. Based on the suitable environment analysis, the high yielding and the most adapted genotypes were Tawa, IT93K-452-1 and Kpodjiguèguè, with yield values of 101.88 Kg/ha-1; 227.16 Kg/ha-1 and 186.35 Kg/ha-1, respectively. This study provided status of screened accessions of which somes are resistants and others are high yielding and stable across environments. These accessions are relevents for breeders and could be used to improve cowpea’s resistance to the flower bud thrips and hence improve productivity and incomes of farmers in Benin.Item Genetic Diversity and Population Structure of Cowpea (Vigna Unguiculata (L.) Walp) Accessions.(University of Ghana, 2019-07) Zoryeku, P.D.A.The research was carried out to study diversity (phenotypic and genetic) and population structure of cowpea germplasm assembled from the DPEB and SARI. A total of 78 cowpea accessions from these two sources were used for the study. Data was collected on twelve vegetative and reproductive traits, four polyphenols, crude protein, seven mineral elements, nineteen amino acids and three SSR markers. Methanolic extracts of pulverized cowpea seeds were used to determine concentrations of polyphenols, crude protein, mineral elements and amino acids. Cowpea Descriptor of the IBPGR (1983) was used for data collection on morphological traits. Data analysis involved descriptive statistics, Fisher’s test of association, Pearson’s pairwise correlation, phenotypic and genetic diversity, Nei’s diversity of subdivided population, principal component analysis and cluster analysis. Mean percent crude protein was 13.52+0.245%. Mean sodium concentration was (35.66+0.58) x 10-3 ppm. Mean potassium concentration was 10.41+0.259 ppm. Mean concentration for magnesium was (0.288+7.69) x 10-3 ppm. Mean concentration for iron was 0.048+0.0041 ppm. Mean nickel concentration was 0.033+0.0021 ppm. Mean concentration for lead was 0.038+0.006 ppm. Mean concentration for cadmium was (7.0+2.0) x 10-4 ppm. Concentration mean for manganese was (0.0187+9.0) x 10-4 ppm. Mean concentration for zinc was (0.00402+8.34) x 10-4 ppm. Mean concentration for gallic acid was 6.97+22.94 mg/l. Mean concentration for syringic acid was 104.25+12.04 mg/l. Mean concentration for quercetin was 69.58+2.34 mg/l.Mean concentration for vanillic acid was 52.79+13.75 mg/l. Mean concentration for L-Histidine was (365.0+42.9) x 10-8 ppm. Mean glycine concentration was (260.0+50.7) x 10- 8 ppm. Mean concentration for L-Asparagine was (2400.0+360) x 10-8 ppm. Mean DL-Alpha- Alanine concentration was (2490.0+296.0) x 10-8 ppm. Mean concentration for L-Aspartic acid was 791.0 x 10-8 ppm. L-Valine mean concentration was (831.0+85.7) x 10-8 ppm. Mea concentration for L-Proline was 957.0+131.0) x 10-8 ppm. L-Methionine mean concentration was (293.0+16.9) x 10-8 ppm. Isoleucine mean concentration was (841.0+15.1) x 10-8 ppm. Mean concentration of Trans-4-Hydroxy-L-Proline was (856.0+13.9) x 10-8 ppm. Mean concentration for L-Tyrosine was (6350.0+933.0) x 10-8 ppm. DL-Beta-Phenyl-Alanine mean concentration was (29840.0 +10040) x 10-8 ppm. L-Tryptophan mean concentration was (646400.0+8700) x 10-8 ppm. Six morphological traits associated significantly with source of cowpea genotype collection: Twenty-two test of associations among the twelve morphological traits were observed. A total of sixty-three significant pairwise correlations were observed among all quantitative traits. Mean total phenotypic diversity (Ht) for percent crude protein and each of the mineral elements was 0.162+0.314. Mean intra-population diversity (Hs) was 0.132+0.021. Mean phenotypic diversity among populations (Gst) was 0.187. Gene flow (Nm) among population’s estimates had a mean of 2.181. Nei’s analysis of phenotypic diversity in subdivided population for polyphenols indicated that mean total phenotypic diversity for each trait (Ht) was 0.121. Mean intra-population diversity (Hs) was 0.105. Mean phenotypic diversity among populations (Gst) was 0.434. Gene flow (Nm) estimate among population for each of the traits ranged from 1.316 to 118.498. The eight SSRs loci had frequencies that ranged from 0.067 to 0.803 and mean Nei’s genetic diversity for the SSR markers was 0.542. Population structure analysis grouped the cowpea genotypes into 4 clusters. Average distance between individual cowpea genotypes in the same cluster ranged from 0.084 to 0.26. Mean genetic differentiation among the four clusters ranged from 0.374 to 0.687. Mean gene flow ranged from 0.228 to 0.837. Eighteen cowpea genotypes were identified to be of economic importance based on concentrations of their phytochemical compounds.