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Research Project: Genetic Enhancement of the U.S. Maize Genepool with Unadapted Maize Germplasm

Location: Plant Introduction Research

Title: Diallel analysis of diverse maize germplasm lines for agronomic characteristics

item HENRY, BRIEN - Mississippi State University
item Blanco, Michael
item ROWE, DENNIS - Mississippi State University
item Windham, Gary
item MURRAY, SETH - Texas A&M University
item Williams, William - Paul

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2014
Publication Date: 6/30/2014
Citation: Henry, B., Blanco, M.H., Rowe, D., Windham, G.L., Murray, S., Williams, W.P. 2014. Diallel analysis of diverse maize germplasm lines for agronomic characteristics. Crop Science. 54(6):2547-2556.

Interpretive Summary: Aflatoxin is one of the world's most problematic carcinogenic (cancer producing) toxins, and is produced in corn grain when infected with the fungus, Aspergillus flavus. Consumption of aflatoxin contaminated grain may lead to impaired growth, liver cancer, and death for livestock and humans. Breeding corn inbreds with a reduced level of aflatoxin has been of limited success, although some inbreds have been developed with reduced aflatoxin levels. A major limiting factor of the currently available germplasm having reduced aflatoxin is lack of adaptation and poor agronomic traits. This includes very late maturity, excessive plant and ear height, and poor grain yield. Nine germplasm sources from the Germplasm Enhancement of Maize (GEM), and six checks with known levels of resistance or susceptibility were studied by making all possible hybrid crosses among the lines (referred to as diallel crosses) and evaluating their performance. The hybrids were studied for two years at two locations in Mississippi State, MS, and for one year in College Station, TX. A diallel analysis was used to determine the general combining ability (GCA) and specific combining ability (SCA) of the inbreds for the traits being studied. GCA is a measure of the average performance of the inbreds in all hybrid crosses, while SCA addresses performance of two specific inbreds. Inbreds Mp317, Mp494, NEI9008, and GEMN-0130 all had positive GCA for increased yield. This was of interest since a previous study found Mp494, and GEMN-0130 had reduced level of aflatoxin. Two GEM lines contributed to GCA for earlier maturity, and four GEM lines contributed to GCA for lower plant height. New sources of germplasm with reduced aflatoxin, improved yield, earlier maturity, and lower plant and ear height provide breeders with useful genetic resources and their use in breeding programs may broaden the germplasm base.

Technical Abstract: Diverse, novel maize germplasm from the Germplasm Enhancement of Maize (GEM) Project and aflatoxin resistant and susceptible maize lines were used as parents to produce diallel crosses. This manuscript documents the agronomic performance of the progeny of the diallel crosses. Nine GEM germplasm lines and six known resistant and susceptible lines were selected as parents of the diallel hybrid progeny that were evaluated over two years at Mississippi State, MS and one year at College Station, TX. Mp317, Mp494, NEI9008, and GEMN-0130 had positive and significant GCA effects for yield in at least two of the three environments. This is especially useful because prior research suggests that both Mp494 and GEMN-0130 also reduce aflatoxin accumulation. Of the GEM lines evaluated, NEI9008 was the best source for enhanced yield with significant and positive GCA values across all three environments. Mp313E x GEMN-0157 yielded well across all environments with an additional benefit of relatively low aflatoxin accumulation in the Mississippi environments. Because the GEM lines evaluated in this diallel cross have a distinctly different genetic background than the aflatoxin resistant Mississippi inbreds, NEI9008 and GEMN-0130 (improved yield); GEMS-0002 and GEMS-0074 (earlier maturity by 3 to 4 days); CUBA117, GEMS-0030, GEMN-0071, GEMS-0100 (reduced plant height 0.1 to 0.2 m) GEMN-0157, NEI9008, GEMS-0002, and GEMS-0074 (reduced height by 0.3 to 0.4 m) should be useful sources of alleles for pyramiding improved yield, earlier maturity, and shorter plant heights into improved breeding lines.