Maize is a valuable crop with high genetic variability, and understanding this variability is essential for improving crop productivity and resilience to environmental stressors. This study evaluated the genetic variability and heritability of yield and yield-related traits among 27 drought-tolerant maize genotypes in a humid climate region of Southwestern Nigeria. The experiments followed rigorous agronomic, soil, and climatic requirements for maize cultivation. Our findings revealed significant genetic variability among the traits of the maize genotypes, particularly in the number of ears per plant, which had the highest genetic advancement as a percentage of the mean (68.25 % and 67.83 %) under both well-watered and drought conditions, respectively. This suggests that breeding programs targeting this trait could significantly improve maize productivity and resilience to drought stress. Additionally, most of the agronomic traits targeted were highly heritable with heritability values ranging from 0.76 to 0.99 under both environments where the genotypes were evaluated, thus indicating that selective breeding for these traits could lead to consistent improvements in maize yields over time. Overall, this study highlights the importance of evaluating yield-related traits’ genetic variability and heritability in maize breeding programs. Findings suggest that targeting the number of ears per plant in drought-tolerant maize genotypes as revealed in the study could be an effective approach for improving crop productivity and resilience in regions with variable moisture regimes.

Biplot analysis has emerged as a crucial statistical method in plant breeding and agricultural research. The objective of this research was to identify the best-performing genotype(s) for the environments in three distinct regions of Nigeria while also examining the characteristics and magnitude of genotype–environment interaction (GEI) effects on the yield of Bambara groundnut (BGN). The study was conducted in Ibadan, Ikenne, and Mokwa, utilizing a sample of 30 accessions. The yield of BGN was found to be significantly affected by accessions, environment, and their interaction through a combined analysis of variance, with a p-value < 0.001. Biplots were utilized to demonstrate the pattern of interaction components, specifically the genotype’s main effect and genotype–environment interaction (GEI). The initial two principal components elucidated the complete variance of the GGE model, encompassing both genetic and genotype-by-environment interaction effects (PC1 = 87.81%, PC2 = 12.19%). The accessions that exhibited superior performance in each respective environment, as determined by the “which-won-where” polygon, were identified as TVSu-2223, TVSu-2236, TVSu-2240, and TVSu-2249 in Mokwa; TVSu-2214 in Ikenne; and TVSu-2188 in Ibadan. The accessions TVSu-2207 and TVSu-2199 exhibited stability in all environments, whereas the accessions TVSu-2226, TVSu-2249, TVSu-2209, TVSu-2184, TVSu-2204, and TVSu-2236 demonstrated adaptability. In addition, the accessions TVSu-2240 and TVSu-2283 were stable and adaptable in all environments. The accessions that were chosen have been suggested as suitable parental lines for breeding programs aimed at enhancing grain yield in the agro-ecological zones that were evaluated. This study’s findings identify BGN accessions with adaptability and stability across selected environments in Nigeria, suggesting specific accessions that can serve as suitable parental lines in breeding programs to enhance grain yield, thereby holding promise for improving food security.

Using 20 pairs of SSR primers situated on each chromosome of the maize genetic makeup, 27 drought-tolerant maize genotypes obtained from the Germplasm Unit of the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, were examined for diversity. The samples' genomic DNA (gDNA) was extracted using the CTAB procedure specified by CIMMYT (2005). All 20 pairs of SSR markers used in this investigation were extremely polymorphic, resulting in 122 repeatable and polymorphic bands that were scored with an average of 12.20 alleles. Each primer yielded a main allele frequency of no more than 0.5. The average major allele frequency for the 10 primers was 0.3036. With an average of 0.8334, all markers had gene diversity values greater than 0.6. Similar to this, the Polymorphic Information Content (PIC) values had an average of 0.8164 and varied from 0.9051 (primer umc1042) to 0.6639 (Umc1669). Since primer umc1042 best identified this variability, the frequency of the main alleles generated by each primer points to the presence of significant molecular genetic variation across the samples under study. This occurrence is further supported by the gene diversity (GD) and polymorphism information content (PIC) values of the primers. Therefore, it can be inferred that the primers are all appropriate for genotyping genetic diversity. Due to their different genetic relationships, varieties IWD C2 SYN F2 and SAMMAZ 52 have the most diversified genotypes and can be utilised as parent materials in a maize breeding programme.

Winged bean [Psophocarpus tetragonolobus (L.) DC.] is an underutilized legume with the potential to contribute to nutrition and food security globally, particularly in sub-Saharan Africa (SSA). However, more attention needs to be paid to exploiting its full potential due to a lack of adequate knowledge of the existing genetic diversity in the available winged bean germplasm. To bridge this gap, thirty accessions of winged beans sourced from the Gene Bank of the International Institute of Tropical Agriculture (IITA), Ibadan, were evaluated for seed morphometric and selected agro-morphological traits at three agro-ecological zones in Nigeria. The data obtained were subjected to analysis of variance (ANOVA), principal component (PC) analysis, cluster analysis, and correlation analysis. Significant differences (p < 0.05) were observed among the accessions for all measured traits. The first two PCs accounted for 88.2% of the variation observed among the accessions for all measured traits. Accessions were grouped into three clusters based on the agro-morphological traits and three clusters under the multi-spectral imaging (MSI) system. TPt-31 had the highest seed yield per plant, pod weight per plant, and early maturity, while TPt-7 had an extended flowering and maturity period, the highest number of pods per peduncle and pods per plant, as well as the lowest seed yield. These accessions could be a good resource for future winged bean improvement programs. The result also confirmed that the MSI system is an invaluable tool for discriminating among accessions of the same crop species. The findings of this study provide insight into the genetic diversity of winged bean germplasm, which could contribute to improving its yield and quality in SSA and globally.

Abstract Okra is an important vegetable crop, but its optimal production is constrained by a myriad of problems including pests, poor agronomic practices, and improper varietal identification among others. A study was carried out to determine the field performance and contribution of agronomic characters to overall variation in eighteen okra genotypes over two locations, Teaching and Research Farms of the Federal University of Agriculture, Abeokuta, Nigeria and Rehoboth Farms Limited, Moniya, Ibadan, Nigeria. The experiments were laid down in a randomized complete block design with three replicates and data were collected on number of days to emergence, number of days to 50% flowering, number of branches per plant, pod length, pod width, number of pods per plant, plant height, pod weight, number of seeds per pod, number of ridges per pod, 100 seed weight, seed, and pod yield. The data were subjected to analysis of variance, heritability in the broad sense, principal component analysis as well as the single linkage cluster analysis. Results revealed significant (p <0.05) variation in the genotypes and high heritability estimates for most of the characters. Number of branches per plant, plant height, number of pods per plant accounted for the highest contributor to variations in the accessions while clustering analysis revealed genotypes; NGB00303, NGB00342 and NGB00346 were distant from all genotypes making them useful materials for hybridization studies.

Abstract Cucumber (Cucumis sativus L.) is an important vegetable crop, rich in vitamins and minerals and eaten fresh as a dessert. Its fruit yield is relatively low, though could be improved through knowledge of character association with it and selection of desirable materials for improvement programmes. Fifteen cultivars of Cucumber were evaluated at two locations (Abeokuta and Ibadan), South West, Nigeria in a randomized complete block design with three replicates in order to determine heritability, correlation, direct and indirect effects of characters on fruit yield. Data collected on agro-morphological characters were subjected to analysis of variance, estimates of heritability, correlation, and path analysis. Significant variations (p <0.05) were observed in the cultivars. High heritability estimates (>90%) was observed for fruit length at both locations. A significant phenotypic and genotypic correlation was observed between fruit yield and fruit weight. Number of days to 50% flowering and fruit width could also be selected directly for improvement of fruit yield in cucumber.

ASTRACT Knowledge of character association and contributions to variability are very important in selection of traits for improvement as well as discrimination of germplasm in improvement programmes. Twenty accessions of jute (Corchorus olitorus L.) were evaluated in two locations in 2018 in a randomized complete block design in order to determine the heritability of characters, their association, their direct and indirect effects on seed yield as well as their contributions to overall variability. Data collected were used to statistical analysis and variance components were used to compute the broad sense heritability estimates, correlation and path analyses as well as principal component analysis. The results revealed high heritability estimates for number of days to flowering, petiole length, plant height, 1000 seed weight and seed yield. Significant (P<0.05) positive correlations were observed for 1000 seed weight at both locations. Changes of genotypic correlations between seed yield and other agronomic traits occurred between environments indicating the influence of environmental factors to trait correlation. The highest direct effect on seed yield was recorded for 1000 seed weigth. The first four principal component axis accounted for over 60% of the total variation in both locations, while characters such as number of days to flowering and number of days to podding were the distinguishing features in accounting for over variation in the accessions. Keywords: Corchorus accessions, correlation, path analysis, PCA

Soybean [Glycine max (L.) Merr.] responded differently to storage stress factors. This research work aimed at assessing genetic potentials of fifteen soybean varieties to storage stress via accelerated aging technique and grouping them based on their levels of tolerance to storage stress using simple sequence repeat (SSR). Tolerance of the seed of 15 soybean varieties to storage stress was assessed by subjecting them to accelerated aging for 0, 6, 12, and 24 hours at 42 °C temperature and 100 % relative humidity (RH), after which their quality was assessed to determine their tolerance to storage stress. Same varieties were also stored for 6 months under ambient environment at 65 ± 5 % R.H and 25 ± 2 °C and they were genotyped with 19 simple sequence repeat (SSR) markers. The varieties were grouped on the basis of their levels of tolerance to storage stress. The principal components analysis (PCA) showed that germination rate index (GRI) and germination index (GI) were the major indices responsible for the significant variation in the seedling vigor characters. TGX1835-10E and TGX1448-2E were identified as varieties with good storage ability and therefore recommended for storage improvement in soybean breeding programs. Six SSR markers (Satt 565, Satt 175, Satt 281, Satt 600, Satt 160 and Satt 281) were identified as candidate markers for detection of alleles for tolerance to storage stress.

Pepper (Capsicum L.) is a widely consumed vegetable in South West Nigeria because of its nutritional and medicinal potentials. This study is aimed at evaluating genetic diversity among 30 pepper accessions collected from different pepper-growing areas in South West Nigeria using SSR markers. Amplification potentials and bands clarity were considered for selecting 17 among 29 SSR markers screened. Genetic diversity was evaluated using principal coordinates analysis (PCoA), cluster analysis (CA), and analysis of molecular variance (AMOVA). The sum of 208 alleles was detected with an average value of 12.24 alleles per locus for each accession. Genetic diversity was high in all loci with the mean value ranging from 0.23 to 0.77. The result of AMOVA showed that 2 % of the genetic diversity was due to interspecific variations while 98 % of the differences were due to intraspecific variations among accessions. The results of cluster analysis showed clearly high genetic similarity coefficient at > 71 %. The intraspecific and interspecific genetic relationships observed could be an integral part of the useful tools for genetic improvement of the genus Capsicum through breeding purposes especially the wild varieties.

Amaranth, is an annual plant used as leafy vegetables, grains and ornamentals. It is a plant with a wide range of variability. Ten Amaranth genotypes were selected based on their morphological features and were evaluated over two seasons in 2016 at the Teaching and Research Farms, Federal University of Agriculture, Abeokuta, (FUNAAB), while the molecular analyses were carried out at the Laboratory of the Biotechnology Centre, FUNAAB. DNA extracted from young amaranth leaves were amplified using four Random Amplified Polymorphic DNA (RAPD) primers (OPA-02, OPA-10, OPB-11 and OPB-12). Data collected were subjected to statistical analyses. The Analysis of Variance revealed significant variation in the accessions with respect to height at flowering and number of branches only. Heritability estimates ranged from 60 – 94% for petiole length and number of branches, respectively. A significant and negative correlation was observed between number of branches and seed weight (-0.35**). Molecular cluster analysis showed that all the accessions studied shared a similarity at a coefficient of 0.55 and two major clusters were formed at a coefficient of 0.60. For hybridization studies, accessions NGB-96 and NGB/09/09 which were from distant cluster could be used as parents to take advantage of the inherent variability. Other markers such as Simple Sequence Repeats (SSR) could be used to further reveal diversity in the accessions.

Variability is germane in crop improvement. The ability of molecular markers to reveal polymorphism can assist in identifying the specific loci of a particular trait in crops. Sequence related amplified polymorphism (SRAP) is a useful technique for determining the genetic diversity of plants and was used to discriminate fifty 'egusi' melon accessions from different parts of Nigeria. The fifty accessions were subjected to SRAP analysis and 65.48% of the bands were found to be polymorphic with similarity coefficients of the accessions ranging from 0.51 - 0.96. Accessions DD98/3, NG/AU/MAR/09/012, NG/OE/MAR/09/015, NG/AO/APR/09/032 and A17 were found to be distinct from all other accessions. The high level of polymorphism exhibited by the 'egusi' melon accessions show they would be useful for maintaining genetic diversity in future breeding programs.

Cowpea, Vigna unguiculata (L.) Walp is one of the world’s main legumes and is an important source of plant protein in human diet as well as a good cover crop. The wealth of any germplasm is measured in terms of the genetic variability. Hence, numerical tools such as single linkage cluster analysis (SLCA) and principal component analysis (PCA) have been used to determine the extent of variability. This study was conducted to determine the performance, character contribution as well as variation pattern in eight cowpea genotypes collected in Nigeria. Field evaluations were carried out in June and September, 2015 and also molecular studies. Data collected were subjected to analysis of variance and Duncan’s multiple range test was used to separate significant means at 5% probability level. Molecular data were subjected to NTSYS-pc software. Genotype IT98K-573-1-1 had the highest 100-seed weight (26.06g) and seed weight per plant (36.00g). The first three PCA had eigen values greater than one and accounted for 75.48% cumulative variance. Pod length, 100-seed weight and seed weight per plant contributed significantly to the overall variation observed in the genotypes. The agro-morphological and molecular dendrograms grouped the genotypes into four and three groups, respectively with genotype IT98K- 73-1- 1 clearly distinguished by the molecular dendrogram. Knowledge of the character contribution as well as variation pattern will assist plant breeders in the choice of parents for hybridization in future breeding programmes. Key words : cowpea, genotype, dendrogram, PCA, SLCA

35S promoter from the Cauliflower Mosaic Virus (pCaMV) is a constitutive promoter commonly used in plant genetic transformation while Cassava Mosaic Virus (pCsVMV) is another promoter which is underutilized. The combination of the two promoters was used to form (pOYE153). The method adopted includes the insertion of a β–glucuronidase reporter gene (UidA) into a promoter cassette comprising the CsVMV promoter. The second construct (pCAMBIA2310) had (pCaMV) used for the selectable marker and gene of interest. This construct was mobilized into Agrobacterium tumefaciens strain LBA4404 and then tested for expression of the UidA gene in transient assays in cassava somatic embryos. After co-cultivation of these Agrobacterium with the plant tissues, histochemical β–glucuronidase (GUS) assays were performed to determine the level of UidA gene expression in transient assays. The results showed that the pCsVMV was able to drive high gene expression of β–glucuronidase reporter gene (UidA) in the transient assays in cassava somatic embryo. Expression of the gene also increases with the increase in the day of cocultivation and likewise expression of the gene was higher for the sample in the light than the dark.

Somaclonal variants arising from clonally propagated plants via plant tissue culture could possess resistance to some diseases. Cotyledon, leaf, and hypocotyl explants from a local variety of Fusarium wilt-susceptible tomato (Solanum lycopersicum L. cv. Beske) were cultured on callus induction media (CIM) with kinetin, 6-benzylaminopurine (BAP), and naphthaleneacetic acid (NAA) at various concentrations. Calli were transferred to shoot regeneration media containing kinetin and BAP in combination with giberellic acid at 0.5 mg/l. Regenerated plantlets and nursery-raised seedlings (control) were inoculated with Fusarium wilt pathogen. Callus induction was between 85.71% and 100.00% on all CIM except hormone-free medium. Disease incidence (70%) and severity score of 3.43 using the area under disease progress curve and taken at 14 days after inoculation were lowest in variants regenerated from leaf explants. We concluded that somaclonal variants of tomato with moderate resistance to Fusarium wilt could be generated in vitro from a susceptible variety through manipulation of growth media.

In vitro regeneration of plants is an important tool in both basic and applied studies as well as commercial applications. It can be of use in overcoming the constraints of tomato production. Assessment of seed sterilization procedures and in vitro regeneration of tomato cultivar was attempted using different explant sources. Seed sterilization procedures with and without ethanol treatment and varying duration of application were used while explants were cultured on Murashige and Skoog (MS) medium only and MS media with varying concentrations of cytokinins and fixed concentration of auxin as Regeneration media (RM). Seeds sterilized with 10% (v/v) solution of sodium hypochlorite for 10 min with two to three drops of non-ionic surfactant (Tween 20) added without ethanol treatment and repeated for 5 min gave the highest germination percentage of 57.33% and percentage contamination of 11.11% compared to seeds sterilized with other disinfection procedures. MS media supplemented with 2 mg/l Kinetin and 0.1 mg/l NAA produced average shoot initiation values of 1.71, 1.57 and 1.57 and average root initiation values of 0.57, 0.00 and 2.85 for cotyledon, hypocotyl and leaf explants respectively. The study showed that the tomato cultivar could be amenable for crop improvement and micro propagation purposes. Key words: Seed sterilization, In vitro regeneration, explant, cultivar, organogenesis.

A study was conducted during 2008 to 2009 in 12 environments in Nigeria, Benin Republic and Togo to evaluate genetic variation and heritability of yield and related traits in 48 rice genotypes. The experiments were laid out in a randomized complete block design (RCBD) with three replications. Genotypes differed significantly at p > 0.001 for all the traits studied, which implies that the genotypes contain adequate genetic variability. Phenotypic coefficients of variation (PCV) were higher than genotypic coefficients of variation (GCV) in all the characters across the 12 environments. High heritability estimates were obtained for days to flowering (91.37), days to maturity (86.86), plant height at maturity, number of tiller per meter square, panicle shattering, panicle threshability, panicle per meter and panicle length (72.21) suggesting that the traits are primarily under genetic control. High estimates of heritability, GCV and genetic advance (GA) observed for grain yield is an indication that selection for grain yield could be achieved through phenotypic performance. Furthermore, high estimates of heritability, GA and GCV recorded in these characters could be explained by additive gene action. Low estimates of heritability, GCV and GA recorded for grain yield and number of grains per panicle could be due to non-additive gene effect suggesting that these traits were less responsive to specific environment influences. Grain yield recorded highly significant positive correlation with panicle length (0.28), leaf width (0.40), grain length (0.30), number of panicles per meter square (0.19) and1000-grain weight (0.17). It correlated negatively with basal leaf sheath coloration (-0.33) and grain width (-0.20) in the 12 environments. The current study indicated that more number of tillers, panicles per meter square, long panicles, high number of primary and secondary branch panicles and large 1000-grain weight are important yield related traits and could be used for selection in rice breeding programs. Key words: Correlation coefficients, heritability, phenotypic coefficients, rice, variability, yield components.

‘Egusi’ melon is an important vegetable crop in the tropics and subtropics that is rich in protein, oils and vitamins. Agro-morphological traits, sequence related amplified polymorphism (SRAP) and simple sequence repeats (SSRs) were used to evaluate 50 accessions of ‘egusi’ melon collected from various parts of the country. The FASTCLUS procedure grouped the accessions into ten distinct groups based on agro-morphological data, with accessions NG/TO/APR/09/029 and A23 characterized by long vines and high seed weight per fruit. A total of 197 bands were scored from 26 SRAP primers, while 49 bands were scored for 25 SSR primers. UPGMA cluster analysis based on dice genetic similarity revealed five and six distinct groups for the SRAP and SSR primers, respectively. A higher level of polymorphism was observed for the SSR primers (93.60%) as compared with the SRAP primers (64.65%), though the discriminating power of the SSR primer (2.28) was lower than that of the SRAP primer (3.71). The relatively higher frequency of SSR polymorphism should be helpful in phylogenetic analysis to better understand these relationships in the melon accessions. Key words: ‘Egusi’ melon, Agro-morphological traits, SRAP, SSR, Discrimination

This study was carried out in order to determine the germination and in-vitro regeneration of five accessions of “egusi’ melon. Seeds from de-coated melon were used for germination and in-vitro regeneration was carried out on excised pregerminated cotyledons in MS medium (4.43g of MS, 30g of sucrose, water of pH 5.8, 1M NaOH and 3.5g Gelzan). The highest germination percentages after five days were observed for the accessions DD98/4 and A22. Regenerated cotyledon explants 14 days after plating in MS medium showed accession A22 producing the highest regeneration frequency. The study revealed that DD98/4 and A22 had the highest germination and best regeneration frequency in the Murashige and Skooge (MS) medium, thus making them useful materials for genetic transformation. Keywords: Regeneration, ‘egusi’ melon, cotyledon Nig J. Biotech . Vol. 24 (2012) 35-40