Improvement of a Maize Population by Full‐Sib Selection Alone versus Full‐Sib with Selection during Inbreeding

Maize (Zea maysL.) improvement involves formation, evaluation, selection, and recombination of genetically variable families or inbred lines, and because cultivars must combine many desirable traits, the process can be complicated and lengthy. This study compared 12 experimental open‐pollinated varieties (OPVs) developed from maize population Pool 9A by two approaches, full‐sib (FS) selection alone and FS selection combined with inbreeding with selection for Maize streakvirus(MSV) resistance. The experimental OPVs were evaluated in 13 environments in Africa, including three sites with artificial MSV inoculation. Full‐sib selection combined with inbreeding and selection for MSV resistance [with mild selection for gray leaf spot resistance (GLS, caused by Cercospora zeae maydisTehon & Daniels)], reduced ear height and reduced days to flowering] resulted in OPVs with similar grain yield but superior MSV resistance (P< 0.01), fewer days to anthesis (P< 0.01), and lower ear height (P< 0.05) than OPVs developed by FS selection alone. Each generation (from S0to S3) of inbreeding with selection resulted in OPVs that were 16, 8, 2, and 1% improved for MSV and GLS resistance, ear height, and days to anthesis, respectively. Our results demonstrate improvement of a maize population for MSV resistance and other traits by selection during inbreeding (from S0to S3), without negative impact on gains for grain yield achieved by evaluation and selection among the progenitor FS families.