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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #159172
Title: COMBINING ABILITY FOR RESISTANCE TO SCLEROTINIA HEAD ROT IN SUNFLOWER

Author
item VAN BECELAERE, GUILLERMO - NORTH DAKOTA STATE UNIV.
item Miller, Jerry

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2004
Publication Date: 9/1/2004
Citation: Van Becelaere, G., Miller, J.F. 2004. Combining ability for resistance to sclerotinia head rot in sunflower. Crop Science. 44:1542-1545.

Interpretive Summary: Sclerotinia head rot is a major disease of sunflower. The development of hybrids with adequate genetic resistance is necessary to reduce yield losses. The amount of variation in the germplasm that is due to genetic differences and the importance of each type of gene action involved in the expression of resistance are of special interest to industry and public breeders to select the best strategy for developing resistant hybrids. The objectives of this study were to estimate the general (GCA) and specific (SCA) combining ability of a set of female and male oil sunflower inbred lines in hybrid combinations for resistance to Sclerotinia head rot, and estimate the gene effects controlling this resistance. Six female and male lines were crossed in a factorial mating design. The hybrids were planted in three U.S. environments and one environment in Argentina. GCA effects accounted for a greater proportion of variation for resistance than SCA effects, suggesting that additive gene effects were relatively more important than nonadditive gene effects. The GCA effects of the female lines were relatively larger than the GCA effects of the male lines. This indicates that the female lines are contributing more to resistance than the male lines and breeders should concentrate on finding more resistance in male lines. Also, since additive gene effects are more important, selection can begin at the inbred line development stage, with utilization of testcross hybrids necessary for identifying resistance to Sclerotinia head rot in sunflower.

Technical Abstract: Sclerotinia head rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is a major disease of sunflower (Helianthus annuus L.). The development of hybrids with adequate genetic resistance is necessary to reduce yield losses. The amount of variation in the germplasm that is due to genetic differences and the importance of each type of gene action involved in the expression of resistance are of special interest to industry and public breeders to select the best strategy for developing resistant hybrids. The objectives of this study were to estimate the general (GCA) and specific (SCA) combining ability of a set of female and male oil sunflower inbred lines in hybrid combinations for resistance to Sclerotinia head rot, and estimate the gene effects controlling this resistance. Six female and male lines were crossed in a factorial mating design. The hybrids were planted in three U.S. environments and one environment in Argentina. GCA effects accounted for a greater proportion of variation for resistance than SCA effects, suggesting that additive gene effects were relatively more important than nonadditive gene effects. The GCA effects of the female lines were relatively larger than the GCA effects of the male lines. This indicates that the female lines are contributing more to resistance than the male lines and breeders should concentrate on finding more resistance in male lines. Also, since additive gene effects are more important, selection can begin at the inbred line development stage, with utilization of testcross hybrids necessary for identifying resistance to Sclerotinia head rot in sunflower.