Abstract
Thirty two collections belonging to 27 corn races native to Mexico, Guatemala, Cuba G. R., Dominican Rep., Ecuador, Colombia, Venezuela, Brazil, and Uruguay, were cultivated in 1978 and 1979 at the Experiment Farm (34°34' N, 135°30' E) of the University of Osaka Prefecture, Japan. The purpose of this study was to classify the races by the traits appeared under environments quite different to those of the native habitats, and to estimate relationships of the traits to the native geographical locations of every races used. The races originated from lower latitude exhibited later flowering habit, accompanying by the increase in the number of nodes of stalk, tlle reduction in the number of effective ears on a main stalk which set more than one kernel (Tables 1 and 3), and some modifications of plant parts (Tables, 4, 5 and 6). These trends, however, appeared differently with different races. Characters to tell races included, in particular, growth habits as earliness, plant height, the number of effective ears per main stalk, and the number of tillers per plant. Being examined by the growth habit and geographical location of native habitat, all the races were classified into five groups, each of which have originated from any one of the following geographical regions : I. Atlantic Coast (from Uruguay to the West Indies, including the coastal provinces of Brazil, Venezuela, and the Atlantic side of Colombia), II. Mexican Lowland (lowlands of Mexico including Yucatan Peninsula), III. Mexican Highland (the Central Mesa of Mexico), IV. Highland (highlands from northern Andes up to southern Mexico), V. Colombian and Ecuadorian Pacific Coast. The pattern of growth response to the environment in Osaka was basically similar among the races of the same group, even if their native habitats were distant apart and different in climate, suggesting that the races from the same region possessed related genotypes for expressing the growth habit in Osaka. Published data on the morphological traits and geographical locations of the native races gathered from the Latin America by many authors so far were examined, and the distribution ranges of many families of related races were estimated. These considerations gave the conclusion that each of the five regions is the zone where related races have become differentiated, i.e. the center of racial diffrentiation. The five regions were compared with the primary and secondary centers of maize presented by BRANDOLINI (1970, 1971), and some disagreements found between the two were also discussed.
