Discovering Cacao Genetics: Celebrating Diversity on Our Farm

When people ask, "What variety is your cacao?" it’s a bit of a tricky question to answer. In the world of cacao, nothing is ever as simple as it seems.

The Fascinating World of Cacao Genetics

Cacao is part of the Theobroma genus in the Malvaceae family, with roots tracing back over ten million years in the Amazon rainforest and Central American forests. Wild cacao populations fall into two major groups located in the lower and upper Amazon and Orinoco river basins. The upper Amazon basin in northwest South America is home to the greatest diversity of cacao species. Traditionally, cacao was classified into three main varieties: Criollo, Forastero, and Trinitario. Criollo means “native” in Spanish, while Forastero means “foreign.” The Spanish named the first cacao they encountered in Mexico and Central America Criollo, while cacao from anywhere else was named Forastero. Trinitario is a hybrid between domesticated Criollo and Amelonado Forastero that originated in the mid-1700s in Trinidad.

This three-tier classification has evolved significantly as our understanding of cacao genetics has grown. Recent genetic research has expanded our knowledge to over ten distinct genetic clusters, each with unique agricultural and flavor potentials. These include:

• Amelonado

• Contamana

• Criollo

• Curaray

• Guiana

• Iquitos

• Marañon

• Nacional

• Nanay

• Purús

Current research continues to expand the number of groups in this list.

Cacao trees with different genetic backgrounds frequently cross-pollinate. After nearly a century of open-pollinated hybridization between primarily Trinitario and Upper Amazon varieties, most cacao trees today are a blend of multiple genetic groups, with each tree being a unique individual, similar to humans. This hybridization means most cacao orchards have a lot of genetic diversity, resulting in a potential for a complex range of flavors.

Grafting Cacao

Despite the worldwide predominance of seed-grown cacao trees, the prevalence of grafting, which started in the 1920s, has been increasing. Grafting involves combining two different trees to produce a tree with specific desired traits, such as better fruit quality, disease resistance, and higher yield. The process starts with a rootstock, which is the part of the tree that provides the root system. A scion, which is a piece of a plant with the desired traits, is grafted onto the rootstock. The scion will form the canopy and bear the fruit of the new tree.

Throughout Central and South America, there is a common set of grafted trees often termed “fino de aroma” or fine flavor cacao. This group of clones includes a mix of classic Trinitario types and Trinitario/Upper Amazon hybrids grown together in a mixed field to produce a complex range of flavors while maintaining some genetic diversity and reducing risk by avoiding reliance on a single variety.

Regional Diversity

Given the complexity of cacao genetics, an emerging approach for public understanding is to use local region of origin descriptors. This method celebrates the unique culture and ecosystem of a cacao's place of origin rather than focusing solely on genetic profiles. Each region's cacao has a unique hybrid genetic profile, with no single region being inherently superior. Emphasizing regional diversity helps us appreciate cacao as a species that adapts uniquely to its environment.

Several factors, in addition to genetics, influence flavor and quality, such as regional soils, weather patterns, local ecosystems, farming practices, fermentation, roasting, and conching. Cacao genetics is just one piece of the puzzle in determining the flavor and quality of cacao, and given the complexity of cacao, we are merely scratching the surface of understanding this miraculous, diverse plant.

Cacao Populations on Our Farm

At our farm, about three-quarters of the cacao trees are side-grafted, thanks to experts like Dan O'Doherty and Max Breen of Cacao Services and Colin Hart of Honoliʻi Orchards. Each cacao clone is identified by unique codes, often indicating the scientific organization or location of origin. The varieties grafted on our farm include:

• TRT: An F1 Trinitario clone family, vigorous and precocious, with a Criollo mother and Amelonado father.

• PHL-12: An Acriollado clone, known for good yield and promising flavor.

• TARS-23: A mixed hybrid from a USDA breeding project in Puerto Rico, noted for its ideal tree architecture, high productivity, and quality flavor.

• EET-103: Part of a group of superior “Neo-Nacional” clones from Ecuador, selected for high yield and disease resistance.

• PHL-3: Another Acriollado clone.

• SPA-10: A wild cacao likely collected in the Amazon region near the Peru/Colombia border

• and propagated in Palmira, Valle del Cauca, Colombia.

• ICS-1: A classic Trinitario clone selected for high yield, good quality, and exceptional vigor. The ICS clones derived from a survey of Trinidad and Tobago by F.J. Pound (1930-1935).

• UF-667: A classic Trinitario clone with upright architecture, compact tree, highly productive, large bean size.

• ICS-39: Green/yellow pod classic Trinitario selection. Large pods and seeds, productive, and widely cultivated as fine flavor cacao in Latin America.

• ICS-6: Green/yellow pod classic Trinitario selection. Slightly smaller pods and seeds compared to ICS-39, and reportedly more productive than ICS-39 due to a higher pod count. Widely cultivated as fine flavor cacao in Latin America. This clone was part of an elite grouping that stood out in a 2014 study because it showed "... a link between quantitative chemical data and the sensory results having both high scores for floral flavour as well as floral aroma volatiles."

Our hope is that these diverse clones will improve the flavor and productivity of our trees. On our small 3-acre farm, productivity is important since a good ferment, we’re told, will require at least 120 kg of wet seed. Other than that, though, much of the outcomes of our grafting efforts remain a mystery. We will have to wait and see within the next year or two what flavors emerge from our cacao. And, as we discussed earlier, variety is only one factor in the big puzzle of determining flavor.