Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radiosensitivity of cowpea accessions to gamma irradiation was investigated. Seeds of eight cowpea accessions were irradiated with 60 Co gamma radiation doses of 100, 200, 300, 400 and 500 Gy. The seeds were sown in pots to evaluate the treatment effects on seed germination (SG), seedling survival (SS) and growth habits of M1 generation. Data were analyzed using descriptive statistics. Low rates of SG (10%-45%) were recorded at higher doses (500-400 Gy) in Ife Brown (IB) and its derivatives, whereas high SG rates (74%-94%) were observed in IT90K-284-2 across all treatments. Percentage SS was inversely related to gamma dosage. A wide range of LD50 for SG (329-1054 Gy) and SS (149-620 Gy) were observed across the cowpea accessions. Low LD50 scores for SG (329-516 Gy) and SS (149-357 Gy) were observed among cowpea with rough seed coat, whereas cowpea with smooth seed coat recorded higher LD50 for SG (521 and 1054 Gy) and SS (449 and 620 Gy). Seed germination LD50 and SS LD50 were highly correlated with mean coat thickness (0.899 and 0.937) than mean seed weight (0.621 and 0.678). Gamma irradiation of cowpea seed at low dosage (100 Gy) increased the vigor of M1 seedlings with respect to primary leaf area, terminal leaflet area, seedling height and plant height at six weeks. Doses of 200 Gy and above resulted in a progressive reduction in vigor of plant and seed setting of cowpea. Radio-sensitivity varied with cowpea genotype and was associated with seed testa texture, thickness and seed weight. Low gamma * Corresponding author. F. O. Olasupo et al. 340 irradiation treatment (100 Gy) may be used to enhance seedling vigor, vegetative growth and yield of cowpea at M1 generation.

Coffea canephora is an important economic crop in Nigeria, however, little is known about the diversity inherent within, and the genetic relationship among coffee grown and conserved in the country. We examined the genetic diversity and relatedness among 48 Coffea genotypes which included: (a) C. arabica, C. abeokutae, C. liberica, and C. stenophylla, (b) 14 C. canephora accessions conserved in the germplasm of Cocoa Research Institute of Nigeria (CRIN), and (c) 30 farmercultivated genotypes collected from SouthWestern Nigeria. By analyzing 433048 single nucleotide polymorphisms (SNPs) identified through genotyping-by-sequencing we discovered that previous characterizations of C. canephora based on morphological data were inconclusive. Here, we established the correct number of C. canephora varieties present in the CRIN genebank which was four and not six as previously described based on morphological characters. We found three distinct diversity structures within the C. canephora genepool that were dominated by a single genetic group determined from passport descriptors to most likely be of Congolese (Democratic Republic of Congo) origin. High uniformity was also found among the farmer-cultivated accessions with 99% of them representing C. canephora var. Niaouli as their ancestral background. The analysis showed that the genetic base of coffee germplasm in Nigeria is narrow compared to the large genetic diversity of C. canephora. Therefore, broadening this genetic base through future acquisition and hybridization is imperative. However, the relatively high genetic differentiation (F ST estimate = 0.3037) Electronic supplementary material The online version of this article (

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Food security is being threatening globally as a result of climate change and depletion of natural resources. Cowpea is one of the important crops that is needed to solve the world nutrition problem. Improvement for drought tolerance in cowpea can serve to mitigate the effect of drought stress resulted from climate change. Understanding the magnitude and type of genetic variability help the breeder to determine the selection criteria and breeding methods to be used for improvement purposes under drought stress. Ten cowpea genotypes were evaluated on the field during the dry season for two years in a RCBD (r=3) under well-watered (WW) and water-stressed (WS) environments. Data were collected on both morpho-physiological and agronomic characteristics. There was significant varying degree of reduction across the parental lines evaluated for all the characters. With respect to number of pods per plant, the highest reduction (64.8%) was observed in IT99K-513-21 and the lowest (-211.7%) in IT89KD-288; for number of seeds per pods, the highest (51.4%) in IT99K-513-21, the lowest (-2.7%) in TVU7778; for 100-seed weight, the highest (50.0%) in IT97K-499 and the lowest (-1.3%) in IT93K-432-1 and for total seed weight, the highest (82.8%) in IT92KD-357-3 and the lowest (-20.8%) in Danilla. The phenotypic and genotypic coefficient of variations were larger under WS than WW. Broad sense heritability estimates ranged between 12.3% in number of branches per plant to 99.0% for number of days to 50% ripe pods under WS. This genetic variability to drought stress provides opportunity for cowpea genetic improvement.

The flavor and health benefits of coffee (Coffea spp.) are derived from the metabolites that accumulate in the mature bean. However, the chemical profiles of many C. canephora genotypes remain unknown, even as the production of these coffee types increases globally. Therefore, we used Gas Chromatography-Mass Spectrophotometry to determine the chemical composition of C. canephora genotypes in Nigeria—those conserved in germplasm repositories and those cultivated by farmers. GC-MS revealed 340 metabolites in the ripe beans, with 66 metabolites differing (p-value < 0.05) across the represented group. Univariate and multivariate approaches showed that the ‘Niaouli’ genotypes could be clearly distinguished from ‘Kouillou’ and ‘Java’ genotypes, while there was almost no distinction between ‘Kouillou’ and ‘Java,’. Varietal genotyping based on bean metabolite profiling was synchronous with that based on genome-wide Single Nucleotide Polymorphism analysis. Across genotypes, the sucrose-to-caffeine ratio was low, a characteristic indicative of low cup quality. The sucrose-to-caffeine ratio was also highly correlated, indicative of common mechanisms regulating the accumulation of these compounds. Nevertheless, this strong correlative link was broken within the ‘Niaouli’ group, as caffeine and sucrose content were highly variable among these genotypes. These ‘Niaouli’ genotypes could therefore serve as useful germplasm for starting a Nigerian C. canephora quality improvement breeding program.

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