The identification or formation of heterotic groups and tester lines are important elements in the development of successful hybrid maize breeding programs. This study was designed to evaluate yield performance in a diallel set of hybrids formed with 12 advanced inbred lines derived from Pool 9A. The relationship between genetic distance, based on simple sequence repeat (SSR) markers, and grain yield was also examined to investigate the potential usefulness of molecu1ar marker information to improve the efficiency of inbred and hybrid development in Pool 9A type material. Pool 9A was originally developed by CIMMYT in the eastem African region and adapted to transition zone conditions, commonly ranging from 1,500 to 2,000 masl (Beck 2001). It was initially formed as a broad-based gene pool for use in developing widely adapted open pollinated varieties (OPVs) for transition zone ecologies. Various heterotic patterns were combined in this pool including Kitale Synthetic, Ecuador 573, Tuxpeno de Altura, and SR52. Pool 9A (white-grained) and the sister Pool 9B (yellow-grained with origins of about 50% of Pool 9A), are the only populations that CIMMYT has developed for transition zone ecologies. In the 1990s, population improvement in Pool 9A was largely conducted in Mexico. More recently, inbreds from this material have been developed including the first release of two CIMMYT transition zone maize lines (CML463 and 464) in 2002. As this hybrid work is still in its infancy, there is much to leam about heterosis, heterotic patterns, and tester lines in material derived from Pool 9A.

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0311|AGRIS 0301|AL-Maize Program

CIMMYT Staff Publications Collection