Abstract:
Landraces of maize (Zea mays L.) are invaluable sources of genetic
variability for improving agronomic traits, and they hold great
promise in developing new maize varieties with enhanced resilience to stresses. Even though phenotypic characterization is an
inexpensive approach for elucidating variation hidden in genetic
resources, information on the genetic diversity patterns in large
collections of landraces remains limited and this constitutes a major
impediment for their optimal utilization in modern maize breeding
programs. We investigated the extent of phenotypic diversity
among 196 maize landraces, representing gene pools from
Burkina Faso, Ghana and Togo, and 14 improved populations/
varieties from the Maize Improvement Program of International
Institute of Tropical Agriculture (IITA-MIP). The germplasm was
assessed for 26 agronomic traits. Highly significant differences
(P < 0.001) were observed among the accessions for all measured
traits. Cluster analysis separated the maize germplasm into five
major groups, differentiated largely by phenology and overall phenotypic appeal, enabling identification of outstanding genotypes
for further screening for stress tolerance. Wide genetic diversity was
observed between Burkinabe and improved gene pools, suggesting that the original Sahelian gene pool might not have contributed much to modern cultivars. This gene pool offers opportunities
for pre-breeding by providing novel alleles for enriching elite maize
germplasm. Shannon-Weaver diversity index (H’) revealed high
genetic variability among the landraces (H’ = 0.73) and a narrow
genetic base in the improved populations and varieties (H’ = 0.46).
These results provide new insights into the potential of tropical
maize landraces for genetic improvement of maize.
