SELECTION OF MAIZE LANDRACES AS DONORS OF USEFUL AGRONOMIC CHARACTERISTICS IN COMMERCIAL HYBRIDS

Abstract

México is center of origin of maize (Zea mays L.), and as a species it has broad genetic diversity. However, this diversity has been scarcely used by Mexican maize breeding public programs that develop commercial hybrids. It is partly so because current methodologies do not use improved heterotic patterns. This research presents a breeding protocol proposal for incorporation of outstanding native maize germplasm into improved maize heterotic patterns for commercial maize hybrid development, and shows effects of application of this protocol on grain yield and grain size of test-crosses. The proposed protocol has three stages: 1) selection of candidate, improved heterotic patterns, 2) selection and incorporation of native germplasm into improved material, and 3) application of reciprocal recurrent selection method (RRS) with familiar selection modification. Evaluation of this methodology employed a subtropical single-cross from progenitors that incorporated 25 % of germplasm of races of Ancho and Tabloncillo maize. S₁ lines and testcrosses were evaluated in four locations. The proposed protocol effectively incorporated native germplasm into improved germplasm: testcrosses with similar grain yield to the original single cross were identified from both race groups. This protocol was also effective for increasing grain size. This protocol allows incorporation of native maize or improved germplasm to current heterotic patterns or outstanding single crosses.