FRUIT MORPHOLOGY VARIATION AND DOMESTICATION OF Stenocereus pruinosus (Otto) Buxb. AND S. stellatus (Pfeiff.) Ricobb. (CACTACEAE) IN LA MIXTECA BAJA, MÉXICO

Abstract

Fruits of more than 20 species of columnar cacti (14 cultivated, 10 of them of Stenocereus) have been used by several Meso- and Arido-American cultures, but only one species with inedible fruit is considered domesticated. To study the variation in fruit morphology in relation to domestication of Stenocereus pruinosus and S. stellatus in the Mixtec region, during 1995-96 we conducted interviews with growers and made observations and measurements of 18 attributes on more than 300 fruits of the 21 cultivated, tolerated or wild populations of seed the two species. There were significant differences in the majority of attributes for each population and species, except for size and relative weight of the seed, and the number of areoles. Multivariate classification was used to determinate the relationships of populations within a species. The first three principal components explained 62-
67 % of the morphological variation evaluated and were related to fruit size, weight and quality, and seed size and weight. The Mixtec people have selected individuals with large, heavy, sweet and spiny fruits, as well as for variation in color, taste, shape and harvest season. Given the lack of variability of these traits in wild populations, the evidence for their prehistoric consumption and cultural importance, and the current knowledge about its use, it is conclude that cultivation and domestication of these species are probably prehispanic. Selection pressures may have increased during the last few decades to satisfy market demands.