Genetic diversity of a Bambara groundnut germplasm representing accessions from 25 African countries, maintained at the International Institute of Tropical Agriculture (IITA; Nigeria) was evaluated based on seed patterns, qualitative characters, quantitative traits and Diversity Arrays Technique (DArT) markers. The study aimed at identifying important descriptors for germplasm conservation, validating the crop's geographical centre of origin and facilitating the utilization of existing genetic resources. Frequencies and diversity indices of seven types of seed patterns, 12 qualitative and 28 quantitative traits were evaluated for 124 representative accessions and were analyzed by region to elucidate the geographic distribution of descriptor states. In addition, individual plant samples from a subset of 40 landrace accessions were analyzed by assessing 554 DArT markers. Both the phenetic tree constructed from the qualitative and quantitative descriptors and the population structure derived from DArT marker analysis suggested a relatively high genetic diversity among accessions. Higher genetic diversity was observed for the Cameroon/Nigeria region relative to other regions, in agreement with the hypothesis that this region is the centre of origin for Bambara groundnut. Use of an extensive and diverse range of germplasm and an approach that integrated morphological and quantitative descriptors with DNA markers that represent wide genomic coverage offered a powerful way to make inferences about crop germplasm, in support of crop-improvement programs.

Genotypic differences in the ability of immature leaf lobes and apical shoot meristems of cassava to form primary somatic embryos in P-CIM were observed ( p £ 0.05). The mean number of apical meristems forming primary organized embryogenic structures when cultured in embryo induction medium supplemented with picloram (P-CIM) had greatest variability between genotypes (C.V. ¼ 22.70%). Maturation frequencies of primary embryos were genotype-dependent and ranged from 17 to 100%. Secondary embryo formation was also genotype-dependent and their maturation frequencies varied from 48 to 100%. Cyclic somatic embryogenesis was successfully established and maintained in 11 genotypes in P-CIM. All genotypes underwent organogenesis with significant genotypic variation ( p £ 0.05), and organogenic potential ranging from 5.4 to 76.8%. The number of somatic cotyledons forming multiple shoot buds or more than 10 shoot buds per cluster had the greatest variability between genotypes (C.V. ¼ 36.96%) as compared with the overall embryogenic potential. Shoot regeneration ability was neither related to primary embryogenic potential nor to explant type for primary embryo induction. Plantlet regeneration per responding explant ranged from 0.1 to 12. Regenerants established in the field at the frequency ranging from 60 to 100%. DNA content of regenerants was homogeneous and similar to that of mother plants and ploidy level was unchanged (2n ¼ 36). The potential benefits of a systematic tissue culture approach for screening agronomically superior genotypes for regeneration capability and its usefulness in selecting those suited for transgenic programs are discussed.Abbreviations: BAP -benzyl amino purine; DAPI -4,6-diamidino-2-phenylindole; GLM -general linear model; IBA -indolebutyric acid; picloram -3,5,6-trichloro-4-aminopicolinicacid; SSA -sub-Saharan Africa

Multivariate analysis is based on a statistical principle involving observation and analysis of more than one statistical variable at a time. The variability of 434 accessions of rice (Oryza sativa L.) germplasm from Côte d'Ivoire was evaluated for 10 agro‐morphological traits in upland conditions at M'bé, Côte d'Ivoire (7°5′ N, 5°1′ W) in 2002 using augmented experimental design and analyzed with multivariate methods. The unweighted pair group method of the average linkage (UPGMA) cluster analysis, canonical discriminant analysis, and principal component analysis (PCA) were used to analyze the data obtained. This enabled the assessment of the extent and pattern of variation of the germplasm and identification of the major traits contributing to the diversity. Seven cluster groups were obtained from the 10 agro‐botanical traits using the UPGMA. Canonical discriminant analysis showed the contribution of each trait to the classification of the rice accessions into different cluster groups. The first three principal components explained about 72.24% of the total variation among the 10 characters. The results of canonical discriminant analysis and PCA suggested that traits such as plant height, number of days to heading and maturity, tillering ability, and grain size (weight, length, width, and shape) were the principal discriminatory characteristics. It was concluded that variation exists in the germplasm, which provides opportunities for this collection to be useful for genetic improvement.

Cowpea is an important legume in subSaharan Africa where its protein rich grains are consumed. Insect pests constitute a major constraint to cowpea production. Flower bud thrips (FTh) is the first major pest of cowpea at the reproductive stage and if not controlled with insecticides is capable of reducing grain yield significantly. Information on the inheritance of resistance to FTh is required to facilitate breeding of resistant cultivars. The genetics of resistance was studied in crosses of four cowpea lines. Maternal effect was implicated while frequency distributions of the F 2 and backcross generations suggest quantitative inheritance. Additive, dominance and epistatic gene effects made large contributions and since improved inbred lines are the desired product, selection should not be too severe in the early generations to allow for desirable gene recombination. This study suggested that some of the genes involved in the control of resistance to FTh are different in TVu1509 and Sanzi. Broad sense heritability ranged from 56% to 73%. Choice of maternal parent in a cross will be critical to the success of resistance breeding.

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.