LAUSR

There is very limited information on genetic gains and improvement of maize inbred line performance per se that has been attained through introgression of temperate germplasm into tropical maize germplasm to enhance adaptability in target environments. The objective of this study was to determine the genetic gains for grain yield and its components achieved by introgression of temperate germplasm into tropical elite maize inbred lines. A total of 123 maize inbred lines comprising of 76 introgressed inbred lines, 21 tropical inbred lines (negative controls) and 26 temperate inbred lines (positive controls) were evaluated in an augmented design at four sites. The strategy was effective and successful to enhance grain yield, in particular, ear prolificacy. Positive genetic gains were realised for grain yield (5%) and ear prolificacy (46%) relative to the population and mean of checks. Selection for plant and ear height, root and stalk lodging had gains ranging from 2 to 11%. However, traits such as anthesis and silking days and grain moisture content at harvest had low gains. Introgressed inbred line performance per se was impressive because new inbred lines with potential for commercial production were obtained. Inbred line 71-DMLF7_88 showed combined early physiological maturity, high ear prolificacy and grain yield potential that were at par with the mean of the temperate checks. Thus, indicating an improvement in the agronomic performance of the improved tropical based material that normally performs below temperate checks in South African warm temperate environments. In conclusion, introgression of temperate germplasm into tropical elite inbred lines was effective in improving adaptation in warm temperate environments.