Haitian coffee agroforestry systems harbor complex arabica variety mixtures and under-recognized genetic diversity

The study sampled 28 farms, 14 in Nord and 14 in Grande-Anse, across five municipalities (Bahon, Dondon and Grande Rivière du Nord in Nord; Beaumont and Pestel in Grande-Anse). The farms were chosen from a 2021 survey of non-intensive, diversified coffee agroforestry systems carried out by the PITAG program, implemented by AVSF and the Ministry of Agriculture. Leaf samples were collected in November and December 2021, farmers named the varieties they believed they grew, and the samples were genotyped with 96 core SNP markers (KASP) and a second marker set (HiPlex) designed to separate Typica from Bourbon, alongside reference accessions from the CATIE collection and others.

After filtering, 724 individuals were analyzed at 87 loci. Gene diversity in Haitian samples (He 0.33) was only slightly below that of the reference collections (0.37), and it varied mainly between and within farms, with no significant structure by department (p = 0.431) or municipality (p = 0.141). The analysis identified six genetic groups: Typica-like, Bourbon-like, CR95/Catimor-like, Kent/I-60-like, Ethiopian-like, and a sixth group made up only of Haitian samples that matches no reference accession. Of the Haitian samples, 407 were assigned to a variety and 194 were admixed. Four farms were monovarietal and all of them were Typica, while 22 farms held two to five genetic groups. One farm in the north also grew C. canephora (Robusta), which the authors say was not previously recorded in Haiti.

Farmers' variety names matched the genetic groups only in part. For example, 31% of plants called Blou Monntenn belonged to the CR95/Catimor-like group, and none of the Bourbon-like plants was called Bougon. Local knowledge told monovarietal farms from diversified ones but underestimated the level of diversity. The authors suggest that rust-resistant varieties introduced by development projects have mixed with traditional varieties under low-input management, and they recommend phenotypic studies of admixed trees, study of seed and seedling exchange networks, and possibly a Haitian germplasm conservation center. The article states that it is free of all copyright and available under the Creative Commons CC0 public domain dedication.