A PROPOSAL FOR DEVELOPING A YELLOW MAIZE HETEROTIC PATTERN FOR THE MEXICAN TRANSITION ZONE. II. TOPCROSSES AND CROSSES ASSESSMENT

Abstract

In México, reconversion from white to yellow grain maize (Zea mays L.) is a strategic grain production program for the country. The transition zone of México (ZTM), located between 1900 to 2200 m of altitude, is environmentally appropiate for maize production. However, improved, yellow grain maize varieties production is limited. As a strategy for increasing the offer, a heterotic yellow grain maize pattern was identified from a subtropical population (LPC1A RC1 C0 F2), and a tropical high valley’s population (INIFAP-Amarillo Dentado-3). This research evaluated the heterotic pattern of the LPC1A RC₁ C₀ F₂ x INIFAP-Amarillo Dentado-3 hybrid, for commercial development of yellow grain maize hybrids for ZTM. We developed test-crosses from S₂ lines derived from the INIFAP-Amarillo Dentado-3 population, where population LPC1A RC₁ C₀ F₂ was used as a tester. Testcrosses were evaluated in four locations, three of them located in ZTM, and one more in a subtropical location. The outstanding lines for general combining ability were crossed to two subtropical single crosses, where one progenitor of each cross was derived from the LPC1A RC₁ C₀ F₂ population. Three-way crosses were evaluated in three locations of ZTM. Agronomic data for plant and ear were recorded and used to estimate general and specific combining ability. It was concluded that the yellow grain maize heterotic in pattern LPC1A RC₁ C₀ F₂ x INIFAP-Amarillo Dentado-3 is an alternative for developing maize hybrids for ZTM; some of the test-crosses and hybrids in this research were up to 7 d earlier, and grain yield was statistically equal (P ≤ 0.05) or up to 17 % greater than commercial controls.