Identification of stable sources of resistance in sorghum to midge and their reaction to leaf diseases

Sorghum midge (Stenodiplosis (=Contarinia) sorghicola Coquillett) is an important pest of grain sorghum worldwide, and several sources of resistance have been identified in the world sorghum germplasm collection. DJ 6514 and the breading lines derived from it become susceptible to sorghum midge in Kenya. Therefore, we evaluated a diverse array of midge-resistant and -susceptible lines at Alupe, Kenya; and ICRISTAT Center, India, to identify lines with stable resistance across seasons and locations. The test material was also evaluated for resistance to leaf diseases at Alupe, Kenya; to identify lines with multiple resistance to sorghum midge and leaf diseases. Across seasons and locations; IS 3461, IS8884, IS 8887, IS 8891, IS 19476, IS 22806, and AF 28 showed high to moderate levels of resistance to midge, and these lines will be useful for use in resistance breeding programs. Thirty-nine lines showed resistance to midge both under natural infestation and no-choice headcage screening at ICRISTAT Center, India, over four seasons, of which IS 18696, IS 22806, ICSV, 197, ICSV 745, ICSV 88032, PM 20710-2, DJ 6514, and AF 28 were highly resistant. Genotypes IS 3461, IS 8884, IS 8887, IS 8589, IS 19476, IS 22806, ICSV 736, ICSV 90003, and AF 28 showed moderate levels of resistance to both midge and leaf diseases at Alupe, Kenya; and these lines can be used as sources of multiple resistance to these pests. Lines IS 2766, IS 7148, IS 8733, and IS 8589, showed high levels of resistance to leaf diseases in Kenya. Resistance to midge breaks down in some lines at Alupe, Kenya; possibly because of the influence of environment on the expression of resistance or the possible differences in midge populations at different geographic locations