Registration of 25 Sheath Blight Disease-Resistant Germplasm Lines of Rice with Good Agronomic Traits

Sheath blight (SB; caused by Rhizoctonia solani Kuhn AG1-1A [teleomorph: Thanatephorus cucumeris (A. B. Frank) Donk.]) is one of the most important rice diseases in the southern United States. Twenty-five rice (Oryza sativa L.) germplasm lines (Reg. No. GP-115, PI 658312 to Reg. No. GP-139, PI 658336) with high levels of resistance to SB were developed and released by the Department of Plant Pathology and Crop Physiology at the Louisiana State University Agricultural Center, Baton Rouge, LA, and the Rice Research Station, Rayne, LA. The lines were developed from 25 yr of recurrent selections of crosses and backcrosses of various SB-resistant sources and U. S. cultivars. Sources for SB resistance included LSBR-5, LSBR-33, H4/CODF, 'Taducan', Rice/Grass, 'Teqing', 'Jasmine 85', 'Katy', 'Yangdao-6', and 'Azmil', combined with SB resistance sources from previous crosses. Panicle rows tested in 2007 were derived from crosses made in 1997-2004, based on a modified recurrent-selection scheme and inoculated each year with SB inoculum. Short-stature, early-maturing, high-yielding lines similar to the commercial rice cultivar 'Cocodrie' were selected and yield tested in small plots in 2008. Their SB ratings ranged from 3.3 to 5.2 on a scale of 0 to 9, indicating reactions ranging from resistant to moderately resistant, compared with 8.8 and 7.3 for the susceptible cultivars Cocodrie and 'CL151', respectively. The lines should be useful for breeders and researchers interested in developing new varieties with resistance to SB.