EVALUATION OF EARLY AND INTERMEDIATE CORN VARIETIES IN CENTRAL HIGH VALLEYS OF MEXICO. II. GENETIC DIVERGENCY

Abstract

In order to know the races and parental relationships of some corn (Zea mays L.) populations used in the breeding programas of the
Highlands of Central México, the purpose of this study was to determine the relationships among populations with different genetic
background and to integrate clusters based on numerical taxonomy techniques. A total of 109 corn populations were planted at Metepec, Tecamac, Montecillo and Chapingo, México, under an 11x11 simple duplicate lattice design to be evaluated. Principal components analysis was used for the following characters: days to male and female flowering, plant and ear height, plants and ears number, and ear diameter and length; the graphic dispersion and population classification or clusters were determined by using the average linkage method and the correlation coefficient (cr) component criteria. Results showed seven clusters with a 0.70 rc distance based on the populations typical phenotypic variability, and four clusters with 1.2 rc distance G1, G2 and G3 were considered new clusters adapted to Central High Valleys of Mexico. Using as reference source populations whose main race is known, it was possible to determine the relationships among the Toluca valley populations: Acambay, Stgo. Yeche, Ixthahuaca and Almoloya de Juárez landraces, and the collections: Col-3228, Col3364, Col-3359, Col- 499, Col-1288, Col-1444, Col-568, Col-1396, Col-477, Col-1296 and Col-1439. Some clusters and relationships which were previously unknown, were also defined.