CROSSES OF NATIVE POPULATIONS OF MAME FROM CHALQUEÑO RACE: II. GENETIC GROUPS, GENETIC DIVERGENCE AND HETEROSIS

Abstract

Within the Chalqueño maize race, different regional genetic groups (RGG) can be distinguished, mainly on the basis of geographic origin and kernel traits. The objective of this research was to determine the agronomic performance of these RGG and their heterosis; as well as the relationship between the heterosis and genetic divergence. Forty-nine outstanding native populations of Chalqueño, grouped in twelve RGG and eleven races closely related to Chalqueño, were crossed with three Chalqueño testers (VS-22, Mex-301, and Tester-3). The 111 intervarietal crosses obtained and their parents were evaluated in 1998 in two environments. Heterosis was associated with genetic divergence. In decreasing order, heterosis within the group of testers was as follows, the highest were the RGG Oaxaca (Cajete), races closely related to Chalqueño, DurangoZacatecas, Michoacán I (Bajío) and Hidalgo; no heterpsis was found on the other RGG. The genetic divergence within the Chalqueño race was explained mainly as a response to different natural, agronomic and cultural conditions of selection processes, and also by introgression with other races.