COMBINING ABILITY OF HIGHLAND MAIZE LINES UNDER HIGH AND LOW SOIL NITROGEN CONTENT

Abstract

The objective of this study was to identify highland single cross maize hybrids (Zea mays L.) with high yield potential in soils possessing high and low nitrogen. In 1999, in the Batan, Mexico, We evaluated 19 crosses including A_i x CML349 and x CML246, 33 crosses B_j x CML244 and x CML352, where A_i and B_j were inbred lines derived from populations 902 and 903, respectively, from the International Maize and Wheat Improvement Center (CIMMYT); CML 349, 246, 244 and 352 are tester lines from CIMMYT. The A_i x CML349 and x CML246 crosses plus CMS 939083, ASPROS 721 and TROMBA as checks, all refered to as genotypes A, were evaluated in a complete randomized block design with two replications. The B_j x CML244 and x CML352 crosses and the same checks, all refered to as genotypes B, were evaluated in another similar experiment in the same location and year. From the genotypes A, the best crosses under high soil nitrogen content were A₁₅ and A₁₈ x CML349, 13.4% higher than the best check; under low nitrogen content condition the best was A₈ x CML349, 14.3% higher than the best check. From genotypes B, the best cross under high nitrogen condition was B₂₄ x CML244, 15.7% higher than the best check; under low nitrogen content the best cross was B₂₆ x CML244, 3.3% higher than the same check. The best lines crossed with their two testers were A₁₈, A₂, B₃₂ and B₂₅ under high nitrogen condition, and A₁₈, A₈, B₁₀ and B₃₂ under low nitrogen content.