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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Publications at this Location » Publication #433814
Research Project: Conservation and Utilization of Tropical and Subtropical Fruit, Cacao, Coffee, and Bamboo Germplasm and Associated Descriptive Information

Location: Tropical Crops and Germplasm Research

Title: Unrevealing the compatibility of 16 cacao (Theobroma cacao L.) accessions from the USDA-NPGS germplasm collection

Author
item Vargas Garcia, Christian
item Ayala Silva, Tomas
item Serrato Diaz, Luz
item Cuevas, Hugo
item Lopez, Axel
item Goenaga, Ricardo

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2026
Publication Date: 6/17/2026
Citation: Vargas Garcia, C., Ayala Silva, T., Serrato Diaz, L.M., Cuevas, H.E., Lopez, A.E., Goenaga, R.J. 2026. Unrevealing the compatibility of sixteen cacao (Theobroma cacao L.) accessions from the USDA-NPGS germplasm collection. HortScience. 61(7), 1548–1555. https://doi.org/10.21273/HORTSCI19446-26.
DOI: https://doi.org/10.21273/HORTSCI19446-26

Interpretive Summary: Global cacao productivity can be improved through field planting designs informed by cultivar compatibility. In this study, we evaluated the compatibility of nine clones widely planted in Puerto Rico (TARS-1, TARS-9, TARS-14, TARS-15, TARS-23, TARS-27, TARS-30, TARS-31, TARS-34) in combination with seven recommended clones (Amelonado, Colorado, EET400, ICS45, IMC67, RIM52, and SPA10) to inform future planting combinations that can maximize yield. The results indicate that most clone combinations can be successfully used in orchard design if compatible sources are included. Only a few varieties showed strong self-pollination ability (Amelonado, TARS27); five exhibited low to moderate self-compatibility, and nine were classified as self-incompatible. The clone TARS-23 stood out as both a strong pollen donor and maternal parent, highlighting its dual potential for higher planting frequency within orchards.

Technical Abstract: Global cacao (Theobroma cacao L.) productivity can be improved through field planting design informed by clone-specific compatibility. Most studies have focused on high-yield cultivar development and introgression of disease resistance, while research on crossing compatibility among clones under field conditions remains limited. In this study, we evaluated the compatibility, based on pod set, of nine improved clones widely planted in Puerto Rico (TARS-1, TARS-9, TARS-14, TARS-15, TARS-23, TARS-27, TARS-30, TARS-31, TARS-34) in combination with seven locally recommended and internationally recognized clones (Amelonado, Colorado, EET400, ICS45, IMC67, RIM52, and SPA10) to inform future planting combinations that can maximize yield. These sixteen clones were arranged in a full-diallel design that included 240 intercrosses and 16 selfs, which were evaluated based on the pod retention index. The results revealed that 203 intercrosses were able to generate at least one pod. Two clones (Amelonado and TARS-27; > 40% retention index) displayed self-compatibility, five showed low to moderate self-compatibility (5–40%), and nine were self-incompatible. Both maternal and paternal sources significantly influenced compatibility across genetic backgrounds. The clones TARS-23, Amelonado, TARS-1, and SPA10 showed the highest retention index as pollen donors, while TARS-30, RIM52, TARS-14, and TARS-23 exhibited the highest index as maternal parents. Notably, TARS-23 stood out as both a strong pollen donor and maternal parent highlighting the clone’s dual use potential. The compatibility patterns identified herein will enable the development of informed long-term planting designs that maximize yield and contribute to a more stable supply of cocoa beans for the local chocolate industry.