Registration of the Oilseed Restorer Sunflower Germplasms RHA 472, RHA 473, RHA 474, and RHA 475, Possessing Resistance to Sclerotinia Head Rot

Abstract

The most significant disease threat to sunflower (Helianthus annuus L.) production in most of the world is Sclerotinia head rot (HR), caused by the necrotrophic pathogen Sclerotinia sclerotiorum (Lib.) de Bary. Resistance to Sclerotinia is available in some inbred lines, but no line or hybrid is immune to it and all resistance is quantitatively inherited. There is also a lack of sunflower germplasms with high yield potential, good agronomic performance, and seed quality traits with Sclerotinia resistance. Herein, we describe the development and release of four germplasm lines that each has Sclerotinia HR resistance, competitive yield and oil content, good agronomic performance, and adaptation to the northern Great Plains of the United States and similar regions. RHA 472 (Reg. No. GP-329, PI 670490), RHA 473 (Reg. No. GP-330, PI 670491), RHA 474 (Reg. No. GP-331, PI 670492), and RHA 475 (Reg. No. GP-332, PI 670493) are restorer inbred germplasms that were developed using the pedigree breeding method with early generation testing for herbicide tolerance and fatty acid composition in the seed oil, and testcross hybrid evaluation in later generations for Sclerotinia resistance, yield, oil content, and agronomic performance. RHA 473 has high oleic acid in the seed oil, and RHA 474 and RHA 475 possess tolerance to imidazolinone herbicides. These lines were released by the USDA–ARS and the North Dakota Agricultural Experiment Station, Fargo, ND, to fill the urgent need in the sunflower industry for breeding lines with disease resistance in an elite genetic background.