Two main questions in programs introgressing exotic maize germplasm into
temperate materials are the choice of available exotic sources to work with,
and the proportion of exotic germplasm that should be incorporated into
adapted germplasm. The objective of this study was to compare effects of
different proportions of tropical maize inbred line NC298 in hybrids male
parent on grain yield and grain moisture content, using method of orthogonal
polynomials. Methods of direct crosses and backcrosses were used to form four
hybrid groups (six hybrids each) containing 0, 25, 50 and 75 percent of
tropical exotic germplasm, respectively, by their male parent (or one half of
mentioned proportions in the corresponding hybrids). The linear components of
the germplasm proportions sum of squares, were significant (p<0.01) for both
grain yield and moisture content and the cubic effect (p<0.05) for grain
yield only. Results in this study clearly suggested backcross foundation
populations with an adapted line to be appropriate selection sources for both
grain yield and grain moisture content.
EARLYTROP: A PROGRAM TO ADAPT 100% TROPICAL MAIZE GERMPLASM TO SHORT-SEASON ENVIRONMENTS