Improving Grain Yield and Yield Components of Temperate Maize Using Tropical Germplasm

Abstract

The objectives of this study were: (1) to determine general combining ability (GCA) of 25 inbred lines selected from CIMMYT populations, specific combining ability (SCA), heterotic specific-group combining ability (HSPGCA) of testcrosses from these 25 lines, using four testers; (2) to determine optimum number of testers for evaluating a large number of exotic lines. The 25 exotic lines were crossed with four elite local maize inbred lines (a line × tester design). A randomized complete-block design with three replications was used at two locations. Data on grain yield and five yield-component traits were recorded. Combining ability analysis showed 8 exotic lines to be genetically similar to the testers and could be assigned to the two current maize heterotic groups. Correlation analysis indicated that one tester had correctly selected the top best lines from a large number of exotic lines. However, when line × location interaction is significant, exotic line performance should be evaluated at multiple loc...