Comparison of Conventional, Modified Single Seed Descent, and Doubled Haploid Breeding Methods for Maize Inbred Line Development Using Germplasm Enhancement of Maize Breeding Crosses

Breeding crosses from the Germplasm Enhancement of Maize (GEM) project between exotic accessions and elite Corn Belt Dent inbreds provide a unique opportunity for broadening the genetic base of the U. S. maize (Zea mays L.) crop by incorporating favorable exotic alleles in elite genetic backgrounds. Genetic gains in the GEM program could be enhanced by identifying more efficient breeding procedures for this purpose. We compared four breeding methods, conventional Germplasm Enhancement of Maize (CG), conventional mass (CM), modified single seed descent (MSSD), and doubled haploid (DH) methods, for their relative capacity to produce superior maize inbred lines and hybrids from three GEM breeding crosses: (ANTIG01 x N16) x DE4, (AR16035 x S02) x S09, and (DKXL212 x S09) x S43b. Testcross evaluations of 50 selected lines from each combination of cross and breeding method were conducted across multiple environments, generally revealing no differences among breeding methods. The MSSD and CM methods had higher proportions of the top 10 lines for grain yield and yield: moisture ratio in the second year testcross reevaluations of about the top 28% of lines. Hybrids from MSSD lines tended to have higher grain moisture, but MSSD hybrids with high yield: moisture ratio could still be identified. The MSSD method may be an effective and efficient alternative to both pedigree and DH methods for developing high performing lines from the GEM breeding crosses as it requires relatively fewer resources.