Abstract

Information about how elite maize (Zea mays L.) inbreds of different pedigree sources combine and perform in hybrid combinations will facilitate the selection of parents and breeding strategies for hybrid development. Fourteen medium to late maturing maize inbred lines, derived from the most commonly used source materials in maize breeding programs in Iran, were crossed in a diallel mating design. The 91 F₁ hybrids and the 14 parental lines were evaluated during two years at four locations in Iran for investigation of combining abilities and to determine heterotic patterns among germplasm sources, using a biplot diallel analysis. The graphical representation offered by biplot analysis allowed a rapid and effective overview of general combining ability (GCA) and specific combining ability (SCA) effects of the inbred lines, their performance in crosses, as well as grouping patterns of similar genotypes. GCA and SCA effects were significant for grain yield (GY), number of kernel row per ear (RE), kernel number per row (KR) and thousand-kernel weight (TKW). Based on significant positive GCA effects, the lines derived from LSC could be used as parent in crosses to increase GY, KR, and TKW. The maximum best-parent heterosis values and high SCA effects resulted from crosses B73 × MO17 and A679 × MO17 for GY; K3640/5× K19/1 for TKW; K3653/2 × MO17, B73 × MO17 and A679 × MO17 for KR; and B73 × K3640/5 for RE. The best heterotic patterns were LSC × RYD, LSC × SYN L. and RYD × SYN L., which would be potentially useful in maize breeding programs to obtain high-yielding hybrids in the same climate of Iran.

Key words: Maize (Zea mays L.), heterotic pattern, biplot diallel analysis, general combining ability, specific combining ability, heterosis.