Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/25/2004
Publication Date: 5/1/2005
Citation: Glover, M.A., Willmot, D.B., Darrah, L.L., Hibbard, B.E., Zhu, X. 2005. Diallel analysis of agronomic traits using Chinese and U.S. maize germplasm. Crop Science. 45:1096-1102. Interpretive Summary: Added genetic diversity among commercial maize hybrids may further increase yields and safeguard against vulnerabilities. Introducing foreign/exotic germplasm into current breeding programs would increase the genetic base from which elite commercial inbreds are derived. Grain yield data from our study showed highly significant general and specific combining ability effects with 12 crosses exhibiting high-parent heterosis greater than 20%. The specific combining ability effect and grain yield mean of one cross in particular, Chinese Mix 2 × Mo17(H14)C5, indicated that Chinese Mix 2 has potential for future improvement in yield performance. The goal of providing improved foreign germplasm to U.S. maize breeding programs from which elite inbreds can be derived will most likely be realized starting with the population Chinese Mix 2. This conclusion is based on this population's moderate-to-good rank for most agronomic traits and high grain yield when crossed with Mo17(H14)C5, a good representative population for the Lancaster-based heterotic group, which is well known by many corn breeding programs. This information will assist maize breeders in choosing germplasm to introgress into their programs to maintain and/or enhance genetic diversity.
Technical Abstract: Added genetic diversity among commercial maize (Zea mays L.) hybrids may further increase yields and safeguard against vulnerability. Introducing exotic germplasm into current breeding programs would increase the genetic base from which elite commercial inbreds are derived. Ten populations of maize, created from Chinese and/or U.S. inbreds or strains, were evaluated using Griffing's diallel analysis for combining ability of grain yield, stalk lodging, ear height, flowering time, and European corn borer (ECB; Ostrinia nubilalis Hubner) resistance to estimate their potential as sources of exotic germplasm for U.S. breeding programs. Grain yield general combining ability was greatest for the population Mo17(H14)C5, a Mo17 synthetic improved by half-sib selection using US13 as a tester. Grain yield specific combining ability was greatest in the cross Chinese Mix 2 x Mo17(H14)C5. This cross combination also provided the greatest grain yield mean, which was significantly higher (P = 0.05) than the check hybrid B73 x Mo17. Chinese Mix 2 x Mo17(H14)C5 had more stalk lodging than the B73 x Mo17 and Pioneer Brand 3394 checks. However, because of the high yield potential and other moderate-to-good agronomic traits of the cross combination, Chinese Mix 2 was selected as the most likely candidate population for continued selection. Its large specific combining ability effect with Lancaster type material, which is commonly known in breeding programs, shows potential for further improvement. No native ECB resistance in Chinese germplasm was detected (two environments in one year) compared to the resistant check Pioneer Brand 3184.