The capulín, or black cherry tree (Prunus serotina Ehrh.) is a tree with edible fruits native to North America that has been used not just as a source of food but also as a source of energy (its wood) since prehispanic times. Mexico has three of the five botanical subspecies in the P. serotina botanical complex, which have not yet been characterized for agricultural purposes. It is desirable to determine whether capulín trees comprise a homogeneous group or whether there are separate morpho-types. This study focuses on the morphological variability of seven populations from the western and central regions of Mexico. We used the Hill & Smith Analysis and graphical methods to analyze and interpret data with respect to 22 quantitative morphological characters and 17 qualitative morphological characters, all from different plant organs. Two major geographically and morphologically related groups were clearly identified, and the morphological variability in the study zone was related to taxonomic, genetic and agronomic factors. The results are discussed from a genetic resources perspective. The genetic, cultural, ecological and agronomic implications of these results are also considered, as well as the potential uses for the species. From these results, an agro-morphological characterization can be developed, in order to identify interesting types of capulín for fruit and seed production in agro-industry, or as rootstock for related species and forestry uses. Our results have implications for the conservation and sustainable use of capulín genetic resources in the central and western regions of Mexico.

La tuna (Opuntia spp.) es un fruto que posee cualidades apreciadas por los consumidores en México y otros países; sin embargo, algunas personas no la consumen porque tiene numerosas semillas grandes en la pulpa, lo cual afecta su calidad y limita su aceptación en los mercados. El objetivo de esta investigación fue determinar la factibilidad de producir frutos partenocárpicos de calidad en cuatro variedades de nopal tunero de amplio uso por los agricultores de Zacatecas y San Luis Potosí. Se aplicaron las dosis de 0, 50, 100 y 200 ppm de ácido giberélico (AG3) a flores emasculadas en etapa de pre-antesis de las variedades Amarilla Montesa (Opuntia megacantha Salm-Dick), Burrona (Opuntia albicarpa Sheinvar), Cristalina (Opuntia albicarpa Sheinvar) y Rojo Pelón (Opuntia ficus-indica L.). A las flores testigos (0 ppm) se les dejó polinizar libremente. El diseño experimental fue completamente al azar, con 16 tratamientos resultantes de un arreglo factorial completo con dos factores y cuatro niveles para cada factor (24). La unidad experimental estuvo conformada por una flor. Las aplicaciones se hicieron en 20 flores (repeticiones) de diferentes plantas por tratamiento. Se obtuvieron frutos partenocárpicos con las tres dosis de AG3, con una reducción significativa de su longitud, diámetro y peso. Los frutos con aplicación de AG3 redujeron peso de pulpa, relación pulpa/peso de fruto y grados Brix (ºBx) de la pulpa y de la cáscara; además se incrementó el grosor de la cáscara en comparación con los frutos provenientes de flores sin tratar (testigo). Aunque los frutos partenocárpicos contaban con poca pulpa y cáscara gruesa, esta última presentó lecturas de ºBx similares a las de la pulpa, por lo que la cáscara es potencialmente comestible.

ABSTRACT. The common fig (Ficus carica L.) was introduced intoMexico by Spanish Franciscan missionaries in the 16th century. It is widely assumed that Mexican figs are the Spanish cultivar Black Mission. We collected and propagated 12 fig plants from six landraces from different states in Central Mexico that represent different climate. All of them were grown in a greenhouse at Universidad Autónoma Chapingo, in the State of Mexico. During the experimental period, the greenhouse had an average temperature and relative humidity of 29.2° ± 5.4°C (SEM) and 78.1 ± 6.7% (SEM), respectively. Morphological characterization was done following a selected set of quantitative and qualitative descriptors established by the IPGRI. DNA analysis was based on a combination of ISSR and RFLP markers. We observed great diversity mainly in fruit weight (28.1-96.2 g), fruit shape (ovoid, pyriform), and neck length (0.97-3.80 cm), which could not be explained by environmental conditions such as temperature and relative humidity. The Nei and Li/Dice similarity coefficient between landraces was determined by cluster analysis using the UPGMA method. Based on the morphological characterization and DNA fingerprinting data presented in this study, our results showed that after hundreds of years, black figs have adapted to local environmental condition in Central Mexico, yielding at least six clearly distinct landraces that represent valuable and previously undescribed genetic diversity. We also suggested names for those landraces according to their location and established a basis for further agronomic and molecular characterization of fig landraces.

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