Conserving Maize Genetic Diversity In Traditional Agricultural Systems.

The maize genetic diversity has been developed and maintained by farmers through multiple cycles of empirical selection in traditional agricultural systems. In Mexico, 85.5 % of the maize production is sowing under these conditions. Besides the native populations, the actual maize diversity is determined by the races, racial complexes and their combination as a result of crosses highly strengthened by seed exchange among farmers and local adaptation process. A case study on native populations carried out in Coahuila State in Mexico indicates that genetic diversity shows a continuous pattern among racial complexes, clearly associated to altitudinal and ecological regions. In the Southeast of Coahuila State, the description of maize populations based on quantitative characters of the ear allowed to identify seven races (Celaya, Conico Norteño, Elotes Conicos, Elotes Occidentales, Raton, Tuxpeño and Tuxpeño Norteño) and nine racial complex combinations adapted to a range of altitude between 774 and 2557 masl, which jointly characterize the genetic diversity. Therefore, the racial complexes × native populations’ relationship can be used to define a subset of cultivars in an accepted proportion that represents the maize diversity in order to establish a participatory conservation and management platform. A representative subset of populations may be obtained by a sampling process using a stratified and proportional within group’s relationship.