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Introduction, Increase, Maintenance, Evaluation and Distribution of Cacao Germplasm
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Objectives

 

To identify, characterize, increase, evaluate and preserve in a disease-free environment promising germplasm of cacao.

Introduction

In 2000, chocolate sales in the United States were about $3.4 billion. Total worldwide production of cacao beans was 2,949,009 metric tons being Côte d'Ivoire, Ghana, and Indonesia the largest producers. In the Western Hemisphere, Brazil, Ecuador and Colombia are the largest producers.

 

Partial view of the new cacao germplasm collection at Mayaguez.  The collection will consist eventually of more than 200 accessions.  It will be the only replicated cacao collection in the world which will facilitate publishable field research.
Cacao is at risk from many diseases which thrive in the warm, humid climate in which it grows. It has been estimated that cacao diseases cause losses of potential crops amounting to 43% in America, 9.0% in Asia, 20% in Africa and 13% in Oceania. These losses cause detrimental effects to growers and to the cacao industry in general. Identification of high-yielding clones with resistance to major diseases of cacao and their subsequent increase, preservation and distribution will benefit growers worldwide. Increased resistance to diseases can be accomplished by increasing the genetic diversity of the current narrow U.S. germplasm base, characterizing this germplasm and evaluating promising materials. This project is a component of National Program 301, Plant, Microbial, and Insect Genetic Resources, Genomics and Genetic Improvement.

Photo of cacao pod accession ICS-88 incorporated in GRIN


Cacao pods at various stages of growth.

Materials and Methods

An old cacao collection was renewed and re-established in the field by grafting about 160 clones onto a common rootstock (Amelonado) and adding new clones with known potential for pest and disease resistance.  Cacao germplasm will be characterized and evaluated in replicated plots for superior productivity.  In collaboration with other scientists, molecular characterization of clones will be assessed and plants arising from various methods of propagation (tissue culture, cuttings, somatic embryos, etc.) will be evaluated for yield in the field.  Puerto Rico is an ideal place to evaluate cacao germplasm because the crop is not grown on a commercial scale and offers a variety of soil types and ecological zones in close proximity.

Accomplishments

This project was created in 2001 and merged with the Tropical Germplasm project in 2004.  In 2001, 179 accessions in the old cacao collection at Mayaguez were analyzed through the use of 14 SSR international primer pairs.  Results permitted the elimination of duplicates from the collection and new knowledge on the degree of genetic diversity in it.

Additional Resources

Plant species not part of the NPGS at the USDA-ARS Tropical Agriculture Research Station site, but locally accessible could be made available to bona fide researchers.  Investigators should contact Dr. Tomás Ayala-Silva to arrange request.