Characterization of Mamey Sapote (Pouteria sapota [Jacq.] H.E. Moore & Stearn.) Germplasm at the USDA-ARS Tropical Agriculture Research Station

The mamey sapote (Pouteria sapota [Jacq.] H.E. Moore & Stearn) is a tropical tree fruit in the Sapotaceae, which is native to Central America and southern Mexico.  The tree is used for timber and shade; however it is the sweet, nutrient and vitamin rich fruit that is eaten out of hand, in milkshakes, sherbets or ice creams, that is most prized.  An ex situ collection of twenty-six mamey sapote accessions at the USDA-ARS TARS (Tropical Agricultural Research Station) in Isabela, Puerto Rico was evaluated for horticultural and agronomic traits over a 3-year period.  Six-year-old, clonally propagated trees that were regularly irrigated, fertilized and pruned were used for the evaluation.  Fruit was collected during monthly harvests and a subset of randomly selected fruit for each accession, at each harvest, was analyzed in the laboratory.  Generally, production (number and total weight of fruit per tree) was highest in the summer months (May to August); however, some accessions produced more during the winter and spring months (December to April). ‘Viejo’ was the most productive accession; yielding and average of 70 fruits/tree/year however, fruit size was very small averaging only 294 g/fruit.  In contrast, ‘Adelantado #2’ only produced 45 fruits/tree/year, but because of its larger fruit size (621 g) it ranked highest for total fruit weight.  The range in average fruit size, length, width, mean seed number, as well as mean exocarp weights was considerable and influenced the amount of pulp for each accession. Total soluble solids (°Brix) among accessions ranged from 18.7 to 27.7.  Phenotypic traits measured included fruit shape, measured by a length/diameter ratio that ranged from 1.10 (globular) to 1.71 (elliptical) and exocarp texture which was generally coarse to very coarse, the exception being ‘Tazumal’ with a smooth surface.  Several of the accessions evaluated have shown potential for use in breeding programs and/or as cultivars for industry either for fresh or processed fruit.  Considerable variation in traits measured among the accessions could be an indication of significant genetic diversity, something that is being currently evaluated with molecular markers.