Seed Dormancy in Mexican Teosinte

Seed dormancy in wild Zea species may affect fitness and relate to ecological adaptation. The primary objective of this study was to characterize the variation in seed germination of the wild species of the genus Zea that currently grow in Mexico and to relate this variation to their ecological zones of adaptation. In addition, we compared methods to break dormancy and measured the germination responses of seeds to environment factors that are related to seasonal changes. Teosinte populations representing all the taxonomic and racial groups known in Mexico were collected during the period 2003 to 2008 in twelve states of Mexico. Seed dormancy was classified according to the rate of its loss (depth of dormancy). Results indicated that more than 90% of populations studied had some degree of seed dormancy. Nondormant populations are distributed predominantly in semicold areas, while deep and very deep seed dormancy was found in populations distributed in hot and very hot environments in well defined geographic regions of the Balsas River Basin and in San Felipe Usila, Oaxaca. Mechanical seed scarification was the best method to break dormancy.