Variation in agro-morphological characteristics of cacao,Theobroma cacaoL., in farmers' fields in Nigeria

Abstract

Knowledge of available variability in a crop species provides a guide for the utilization and conservation of useful variation. Seventeen agro-morphological traits were studied in 184 accessions of cacao, Theobroma cacao L. collected from farmers' fields (138) and field genebank collections (46). Descriptive statistics*univariate analysis of variance (ANOVA)*were used to determine variation among accessions. Multivariate analysis with principal component analysis (PCA) was done and a cluster dendrogram was generated based on the unweighted pair group mean with arithmetic average (UPGMA). The first three principal component axes accounted for 43.6% of total variation observed among accessions studied. Quantitative bean traits*dry bean weight, nib weight, fresh weight, cotyledon length and cotyledon width*and qualitative fruit traits*basal constriction, apex form, ridge colour, fruit shape, flush colour and cotyledon shape*were the most important traits accounting for the variability observed. Six groups of accessions were obtained from cluster analysis. Fruit and bean traits of Upper Amazon Forasteros observed in farmers' accessions provided evidence of a shift from previously grown local 'West African Amelonado' from the Lower Amazon Forastero population. In conclusion, this study revealed some accessions with useful trait combinations in farmers' plantations and indicated a need to conserve the local 'Amelonado' landrace variety to avoid extinction and to preserve the unique flavour of 'West African Amelonado' in cocoa breeding programmes.

Assessment of Genetic Diversity in Robusta Coffee Using Morphological Characters

“…The usefulness of cluster analysis in grouping germplasm collection based on similar morphological variations as in the present study has been demonstrated in C. canephora (Aluka, 2013;Anim-Kwapong et al, 2011a), C. arabica (Gessese et al, 2015;Kebede and Bellachew, 2008;Montagnon and Bouharmont, 1996), and many other crop plants, such as cocoa (Aikpokpodion, 2010;Lachenaud and Oliver, 2005) sorghum (Ayana and Bekele, 1999), and rice (Arietta-Espinoza et al, 2005). The cluster analysis allowed for a successful grouping of the Robusta coffee genotypes into five main groups based on the similarity of 13 quantitative characters.…”

Assessment of genetic diversity in horticultural and morphological traits among papaya (Carica papaya) accessions in Nigeria

“…It appeared from this study that papaya accessions in Nigeria exhibit high variability in many important horticultural traits, a possible consequence of use of seeds by farmers. As observed in other crops, farmers tend to obtain seeds from neighbors and self-owned farms from interesting parent trees or individuals for new plantings or farm expansion [23]. Open-pol-linated dioecious varieties of papaya that form the basis of Australia's Queensland industry also tend to be highly variable in characteristics such as fruit shape, taste, size, flesh color, firmness and yield [24].…”

Classification of cacao beans (Theobroma cacao L.) of southern Mexico based on chemometric analysis with multivariate approach

“…Since the chemical composition is associated with quality characteristics exhibited by cacao, the hypothesis that a microclimate can enhance the unique characteristics of flavor quality and aroma, supported by other authors [38], turns out to have a minimum contribution. This phenomenon may have several explanations: (1) either the characteristics of the microclimate in our study are not sufficiently decisive regarding the chemical composition, (2) the accessions have a strong genetic association (highly related individuals) as demonstrated in genetic studies using molecular markers [15] or (3) or trees in adaptive process to the environmental conditions of the Soconusco, Mexico, which could be promoting the particular flavor and other characteristics as demonstrated occurs in other places.…”