Variability of three regional sources of germplasm of Tejocote ( <i>Crataegus</i> spp.) from central and southern Mexico
Tejocote ( Crataegus spp.) is a genus of fruit-bearing trees distributed widely throughout Mexico; 13 species are reported for the north and central zones and two or more species may be present in southern Mexico. Accessions of this genus are safeguarded in the Germplasm Bank of Tejocote at the Autonomous University of Chapingo, mainly from three regional sources, i.e. the states of Puebla, Mexico, and Chiapas, including five different species that belong to series Mexicanae and series Crus-galli. They can be morphologically characterized by leaves from different shoot types, flowers and fruits. Multivariate statistical methods were used to elucidate patterns of variation in each of these regional sources. The sources displayed very low intra-source variability. The source from Chiapas showed significant statistical differences in all morphological variables evaluated, as a result, this genetic pool is considered as different from the other two sources. The sources from the states of Puebla and Mexico only differed by 22.79% (with P ≤ 0.05), and thus they could be considered as components of a single genetic pool. The most highly discriminant variables were from the leaf, such as basal angle, petiole length/major axis length ratio, minor axis length/major axis length ratio, and number of veins.