Resumo

LOPEZ-ROMERO, Gustavo et al. Caracterización morfológica de poblaciones nativas de Maíz del Istmo de Tehuantepec, México. INCI [online]. 2005, vol.30, n.5, pp.284-290. ISSN 0378-1844.

With the purpose of knowing the variation of maize (Zea mays L.) at the Tehuantepec Isthmus region, considered as the distribution area of the Zapalote Chico maize race, 120 native populations were collected and evaluated along with 12 typical populations of other described races. The 132 populations were evaluated in three localities by using 18 quantitative traits, mainly related to reproductive structures. Six groups were observed with the aid of principal component analysis, three of them included populations regionally known as "Maíz Chico", corresponding to the Zapalote Chico race, with smaller values in reproductive, vegetative and phenological traits; the other three groups gathered populations locally denominated as "Maíz Grande", with higher values of the aforementioned traits, and correspond to an ample base of the Zapalote Chico race, with genetic introgression of the races Vandeño, Tepecintle and Tuxpeño. Genetic variation of maize was related to environmental variation as determined by altitude, relative humidity and soil moisture availability, pointing out the coastal plain of the Oaxacan Isthmus as the area of natural distribution of the Zapalote Chico race. A dendrogram was constructed using Euclidian distances through the Neighbor-Joining method, revealing that the "Maíz Grande" groups evolved toward late populations, and those of "Maíz Chico" toward both late and early populations. It is concluded that genetic variation does exist in the maize populations of this region at the race level and among populations within the Zapalote Chico race itself.

Palavras-chave : Zea mays ; Diversidad; Zapalote Chico; Istmo de Tehuantepec; Variación Genética.