African yam bean (AYB, Sphenostylis stenocarpa Hochst. ex A. Rich.) Harms is a tuber and seed crop, rich in protein, with the potential to contribute to food security. To date, available information on the diversity of AYB is scarce. This study aims at understanding the genetic diversity of 79 AYB accessions of various origins. Twenty-four morphological and taxonomic features of high descriptive values were used and the diversity within the germplasm was assessed by clustering analysis. The 79 accessions differed significantly, with the similarity distances spanning from 0.0646 to 0.5720 and a mean distance of 0.2820. The accessions were grouped into five clusters of 10-26 members. Of the 24 phenotypic variables analyzed, variegation in testa color was the most discriminatory trait, classifying the accessions in the proportion of 25% with variegated to 75% with non-variegated seeds. The ranking by significance (P B 0.05) of the ordinal variables of discriminating importance were in the order of pattern of testa variegation, basal color of variegated seeds, and testa basal color. The stepwise discriminant and frequency procedures in SAS identified other phenotypic variables with significant discriminatory attributes, such as pigmentation of plant parts, seed cavity ridges, and pod dehiscence. Accessions with desirable agronomic traits, such as longer pod length, high number of seeds/pod, non-shattering characteristics of pods at maturity, lower number of days to flowering, and a higher seed set percentage, were also identified in this study. These discriminatory traits are discussed and proposed for germplasm conservation and use.

Twenty-nine okra accessions from different agro-ecological regions in Nigeria were grown during the rainy and dry seasons, between 2006 and 2007 at Abeokuta (derived savanah) and Ilishan (rainforest) and assessed to determine their genetic variability, heritability and genetic advance from eight yield related characters. The experiment was laid out in a Randomized Complete Block Design with five replications. There was high genotypic coefficient of variability, % broad-sense heritability and genetic advance in traits such as plant height (26.2, 90.7, 51.5), fresh pod length (23.9, 98.5, 48.8), fresh pod width (23.9, 98.5, 48.8), mature pod length (28.6, 98.5, 52.3), branching per plant (29.3, 82.3, 54.8) and pod weight per plant (33.9, 90.0, 63.3), suggesting the effect of additive genes and reliability of selection based on phenotype of these traits for crop improvement. The positive and significant phenotypic and genotypic correlation between plant height at maturity, fresh pod width, seeds per pod and pods per plant, branches per plant with seed weight per plant and pod weight per plant, suggests that selection on the basis of the phenotype of these characters will lead to high seed and pod yield in okra.Additional key words: accession; derived savannah; genetic advance; genotypic correlation; Nigeria; phenotype. Resumen Variabilidad y heredabilidad genética en quingombó [Abelmoschus esculentus (L.) Moench] cultivadoSe cultivaron 29 accesiones de quingombó de diferentes regiones agro-ecológicas en Nigeria durante las estaciones lluviosas y secas de 2006 y 2007 en Abeokuta (derivada de la sabana) y Ilishan (selva) y se evaluaron para determinar la variabilidad genética, heredabilidad y avance genético de ocho caracteres relacionados con el rendimiento. El experimento fue en bloques completos al azar con cinco repeticiones. Hubo un alto coeficiente de variabilidad genotípi-ca, % de heredabilidad en sentido amplio y avance genético en caracteres como altura de planta (26,2; 90,7; 51,5, respectivamente), longitud de vaina fresca (23,9; 98,5; 48,8), ancho de vaina fresca (23,9; 98,5; 48,8), longitud de vaina madura (28,6; 98,5; 52,3), ramas por planta (29,3; 82,3; 54,8) y peso de vaina por planta (33,9; 90,0; 63,3), lo que sugiere un efecto aditivo de genes y fiabilidad de selección basada en el fenotipo de estos caracteres para mejorar los cultivos. La correlación positiva y significativa, fenotípica y genotípica entre la altura de la planta en la madurez, el ancho de la vaina fresca, las semillas por vaina, las vainas por planta y las ramas por planta, con el peso de las semillas por planta y el peso de las vainas por planta, sugiere que la selección en el quingombó basada en el fenotipo de estos caracteres conducirá a un alto rendimiento en semillas y vainas.

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Accurate knowledge of intra-specific diversity of underutilized crop species is a prerequisite for their genetic improvement and utilization. The diversity of 77 accessions of African yam bean (AYB, Sphenostylis stenocarpa) was assessed by amplified fragment length polymorphism (AFLP) markers. A total of EcoRI/MseI primer pairs were selected and 227 AFLP bands were generated, of which 59(26%) were found to be polymorphic in the 77 accessions of AYB. The most efficient primer combination for polymorphic detection was E-ACT/M-CAG with a polymorphic efficiency of 85.5%, while the least efficient was E-AGC/M-CAG with a polymorphic efficiency of 80.6%. The Jaccard genetic distance among the accessions of AYB ranged between 0.048 and 0.842 with a mean of 0.444. TSs98 and TSs104B were found to be the most similar accessions with a genetic similarity of 0.952. The neighbour-joining dendrogram grouped the 77 accessions of AYB into four distinct clusters comprising 8, 20, 21 and 28 accessions. The major clustering of the accessions was not related to their geographical origin. Cluster I was found to be the most diverse. The mean fixation index (0.203) and the mean expected heterozygosity (0.284) revealed a broad genetic base of the AYB accessions. The same germplasm set was previously evaluated for several agro-morphological traits. As the collection of additional AYB germplasm continues, the phenotypic profile, the clustering of the accessions and the AFLP primer combinations from this study can be used to augment breeding programmes.

The knowledge of agro-morphological diversity and the distribution pattern of variation among conserved accessions could be an invaluable aid in germplasm management and crop improvement strategies. In this study, the geographical pattern of morphological variation of 880 landrace rice (Oryza sativa (L.)) accessions in Côte d'Ivoire was evaluated for 13 agro-morphological characters. Shannon -weaver diversity index indicated an overall mean of 0.47 ± 0.07 in the collection, with the greatest diversity from derived Savanna and northwest (H 0 = 0.52 and 0.50) while the west-central had the lowest diversity (H 0 = 0.41). Canonical discriminant analysis showed that traits such as panicle length, grain size (weight and length), tillering ability, number of days to heading and maturity were the main discriminatory characteristics. Result of the phenotypic frequency shows that, the landraces from the north and north-western zones were mostly tall, early heading and maturity, compared to those from the west and west-central which were mainly dwarf to medium height, late heading and maturing. This differential distribution of landraces with height, heading and maturity period reflected the distribution pattern of different Oryza sativa landraces in Côte d'Ivoire, which could be useful in germplasm management and breeding programs.