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Edward J. Boza, Juan Carlos Motamayor, Freddy M. Amores, Sergio Cedeño-Amador, Cecile L. Tondo, Donald S. Livingstone III, Raymond J. Schnell and Osman A. Gutiérrez

constitution of ‘CCN 51’ is required for effective use of this valuable resource. A sustainable cacao breeding and selection program in Ecuador has been led by the Instituto Nacional de Investigaciones Agropecuarias (INIAP) where an efficient selection process

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Jane M. Marita, José Luis Pires, W. Martin Aitken and James Nienhuis

85 ORAL SESSION 18 (Abstr. 500–507) Breeding & Genetics–Fruits/Nuts

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C.M. Ronning, D.M. Harkins, R.J. Schnell and L.H. Purdy

Cacao is an important crop in the tropics, but its breeding has been hampered by a lack of understanding of its genetics. One result of this has been the introduction of “hybrid” trees which did not perform predictably under various environmental conditions. We are studying the inheritance of isoenzyme, RFLP, and Random Amplified Polymorphic DNA (RAPD™) markers in order to estimate the genetic relationships among and between populations. Our objectives include determining if any linkage exists between these molecular markers and witches' broom (Crinipellis perniciosa) resistance, a major disease of cacao.

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Cuauhtemoc Cervantes-Martinez, J. Steven Brown, Raymond J. Schnell, Wilbert Phillips-Mora, Jemmy F. Takrama and Juan C. Motamayor

Knowledge of genetic differences among commonly cultivated cacao clones, as well as the type of gene action involved for disease resistance, yield, quality, and horticultural traits, are essential for cacao breeders to select parental clones efficiently and effectively. This information is also critical for quantitative geneticists in designing and improving quantitative trait loci (QTL) localization strategies using breeding populations, whether they involve analysis of multiple populations crossed to one common parent or association genetic analysis. The objectives of this research were to 1) verify the genetic identity of parental cacao clones used to produce hybrids for field evaluation at the Centro Agrónomico Tropical de Investigación y Enzeñanza (CATIE), Turrialba, Costa Rica, using molecular marker analysis, and 2) estimate general and specific combining ability (GCA and SCA) of the parental clones for resistance to frosty pod (Moniliophthora roreri Cif. and Par.) and black pod [Phytophthora palmivora (Butl.) Butl.] diseases, total number of pods, vigor (as measured by trunk diameter), and measures of maturity (months to first flowering and pod production). Misidentification of cacao clones was found at three levels. Molecular marker analysis revealed that six parental clones differed in identity to supposedly identical accessions from other germplasm collections. Trees of the parental clone UF 273 consisted of two clearly different genotypes, resulting in two types of progeny, requiring separate designation for correct statistical analysis. Out-crossed progeny, presumably from foreign pollen, and selfed progeny were also found. Two of the traits measured, percent healthy pods and percent pods with frosty pod, showed predominantly additive gene action, while the traits total number of pods and trunk diameter, demonstrated regulation by both additive and nonadditive gene action. Number of months to first flowering and first fruit both showed evidence of predominant regulation by nonadditive gene effects. Crosses of two parental clones, UF 712 and UF 273 Type I, were identified as potential candidates for QTL analysis as breeding populations, given their favorable GCA estimates for frosty pod resistance and total pod production, respectively.

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A.J. Daymond, P. Hadley, R.C.R. Machado and E. Ng

Biomass partitioning of cacao (Theobroma cacao L.) was studied in seven clones and five hybrids in a replicated experiment in Bahia, Brazil. Over an 18-month period, a 7-fold difference in dry bean yield was demonstrated between genotypes, ranging from the equivalent of 200 to 1389 kg·ha-1. During the same interval, the increase in trunk cross-sectional area ranged from 11.1 cm2 for clone EEG-29 to 27.6 cm2 for hybrid PA-150 × MA-15. Yield efficiency increment (the ratio of cumulative yield to the increase in trunk circumference), which indicated partitioning between the vegetative and reproductive components, ranged from 0.008 kg·cm-2 for clone CP-82 to 0.08 kg·cm-2 for clone EEG-29. An examination of biomass partitioning within the pod of the seven clones revealed that the beans accounted for between 32.0% (CP-82) and 44.5% (ICS-9) of the pod biomass. The study demonstrated the potential for yield improvement in cacao by selectively breeding for more efficient partitioning to the yield component.

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Ricardo Goenaga, Heber Irizarry and Brian Irish

breeding line or cultivar. Literature Cited Batista, L.J. 1981 Evaluación de la capacidad productiva de 6 híbridos de cacao en República Dominicana Proc. 8th Int. Cocoa Res. Conf Cartagena, Colombia 713 717 Enriquez, G.A. Paredes, A. 1985 El cultivo del

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Darin A. Sukha, Pathmanathan Umaharan and David R. Butler

, West Indies Warren, J. Kalai, S. Misir, S. 1995 An unnatural breeding system polymorphism in cacao ( Theobroma cacao , Sterculiaceae) in Trinidad Amer. J. Bot. 82 1126 1130 Wood, G.A.R. Lass R.A. (eds.). 1985 Cocoa. 4th ed. Longman, London, UK Yong

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Jane Kahia, Siaka Kone, Lucien Diby, Georges Ngoran, Colombe Dadjo and Christophe Kouame

Cacao ( Theobroma cacao , Malvaceae) is a crop of major importance for the livelihoods of small-scale farmers and ecosystems in many tropical regions. About 72% of the world’s cocoa is produced in Africa, with Côte d’Ivoire being the top producer at

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Samantha Jay Forbes, Guiliana Mustiga, Alberto Romero, Tobin David Northfield, Smilja Lambert and Juan Carlos Motamayor

breeding sites on pollinating midge populations and fruit set in two cocoa farms J. Appl. Ecol. 19 1 1718 1727 Young, A.M. Severson, D.W. 1994 Comparative analysis of steam distilled floral oils of cacao cultivars ( Theobroma cacao L., Sterculiaceae) and

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Gayle M. Volk and Christopher M. Richards

trait of great interest to the garlic industry to reduce production costs. Our final speaker, Ray Schnell, USDA-ARS Subtropical Horticulture Research Station, Miami, FL, emphasized his marker-assisted breeding program for cacao ( Theobroma cacao