The variability of certain bean characteristics of cacao (Theobroma cacao L.)

Enríquez, Gustavo A.; Soria, Jorge

doi:10.1007/bf00038972

Cited by 7 publications

(1 citation statement)

References 2 publications

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“…To describe the morphological diversity, several authors have attempted to define the most efficient• morphological descriptors that take into account the intraand interclonal variance (Enriquez and Soria, 1968;Engels et al, 1980;Soria and Enriquez, 1981;Engels, 1983a, b;Bekele, 1992;Bekele et al, 1994;Raboin and Paulin, 1993). The IBPGR (1981) published a list of 65 morphological descriptors to characterize the genetic resources of cacao.…”

Section: Morphological Diversitymentioning

confidence: 99%

Genetic Diversity of Cultivated Tropical Plants

Hamon¹,

Séguin²,

Perrier³

et al. 2003

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These relationships probably vary as a function of the population structure. They are generally strong if there is a serious gametic disequilibrium. To proceed from this reflection, however, we must tackle specific questions: Are the different types of molecular markers equivalent? Are strong structures at the molecular scale, which control the gametic disequilibrium generalized on the genome as a whole, systematically associated with strong structures for agronomic characters? Do the structures at these two levels therefore coincide?Several methods have been proposed to construct the core collections. As a general rule, they are based on a stratification of the base collection and then on a random sample within each group thus defined, according to various modalities. When data are available for morphoagronomic evaluation, it is useful to consider the structure of the genetic diversity established with the help of genetic markers in order to maximize the agronomic diversity and minimize the loss of alleles that are rare overall but occasionally significant.The constitution of a core collection must therefore be founded on an excellent description of the populations and on a sound understanding of their structure. Statistical tools are indispensable here. For each type of marker, it is important to use a measure of difference between the relevant taxonomic units (individuals or populations) from the perspective of their mathematical properties and their interpretation in genetic terms. In the same way, the choice of algorithms of representation of dissimilarities must be based on an equilibrium between maximum efficiency and minimum complexity, irl order to deal with large tables covering more than 100 individuals. By comparing the structures observed with the help of various types of descriptors, we can envisage overall the organization of a plant's genetic diversity. This question can be tackled in various ways, among others, by looking for structures common to two or several trees. In these conditions, how can we construct consensus trees or common minimum trees? What is their reliability and their biological significance?This work provides the elements of an answer to these questions, beginning with the study of eleven types of plants, chosen .so as to cover a wide range of biological characteristics (perennial, annual, autogamous, allogamous, etc.): asian rice, banana, cacao, cassava, citrus, coconut, coffee, pearl millet, rubber tree, sorghum, and sugarcane. Three methodological chapters complement these studies. The first is devoted to the use of biological and molecular markers to analyse the diversity of collections, the second addresses data analysis, and the third describes a method for constituting core collections based on maximization of variability.

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Section: Morphological Diversitymentioning

confidence: 99%

Genetic Diversity of Cultivated Tropical Plants

Hamon¹,

Séguin²,

Perrier³

et al. 2003

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A systematic description of cacao clones. I. The discriminative value of quantitative characteristics

Engels

1983

Euphytica

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Receiwd 15 Srpremher 1981 INDEX WORDS Theohrcrma cacao, cacao clones. discriminative value, quantitative descriptors. taxonomic identifiers SUMMARYData from 25 possibly distinctive quantitative flower and pod characteristics were collected from 32 cacao clones and analysed statistically. The discriminative value of each of them was calculated by using Duncan's new multiple range test to obtain a discriminatory value 'D' which was adjusted to allow for correlaltions with other characteristics. It is concluded that quantitative characteristics, which usually have a higher agronomic interest than qualitative ones, are also helpful in characterizing and identifying varieties or clones.Euphytica 32 11983)

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Variability and selection for morphological bean traits in wild cocoa trees (Theobroma cacao L.) from French Guiana

Lachenaud

Oliver

2005

Genet Resour Crop Evol

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Under the conditions prevailing at Paracou-Combi (French Guiana), 96 local wild cocoa trees belonging to ten populations from the Camopi and Tanpok rivers, and already pre-selected for other agronomic criteria, were characterized for their average fresh bean weight, an important selection criterion. Other traits, such as the average length and width of a bean, along with the percentage of flat beans, were also studied. The variability found for average fresh bean weight was substantial, with a coefficient of variation of 10.5% and extremes of 2.20 and 3.82 g. The average of 2.97 g (i.e. 1.04 g for a fermented dried cocoa bean) was higher than the control, the Upper Amazon Forastero clone NA 32. The main five populations were not statistically different for the three morphological bean descriptors (average weight, average length and width), but they were for the percentage of flat beans, which was relatively high on average (6.9, on fresh beans). An analysis of variance of the basic data (i.e. per pod on 3250 pods) showed a highly significant tree effect, enabling ortets selection. Given the high heritability of the average bean weight, these ortets could be used as clones, or as parents in crosses with other genetic groups. A list of trees with small beans, hence which ought theoretically to be avoided in breeding programmes, is provided.

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The variability of certain bean characteristics of cacao (Theobroma cacao L.)

Cited by 7 publications

References 2 publications

Genetic Diversity of Cultivated Tropical Plants

Genetic Diversity of Cultivated Tropical Plants

A systematic description of cacao clones. I. The discriminative value of quantitative characteristics

Variability and selection for morphological bean traits in wild cocoa trees (Theobroma cacao L.) from French Guiana

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