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

Sorghum midge (Stenodiplosis (= Contarinia) sorghicola Coquillett) is an im portant 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 -susc eptible lines at Alupe, Kenya; and ICRISTAT Center, India, to identify line s with stable resistance across seasons and locations. The test material wa s also evaluated for resistance to leaf diseases at Alupe, Kenya; to identi fy lines with multiple resistance to sorghum midge and leaf diseases. Across seasons and locations; IS 3461, IS 8884, 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. Th irty-nine lines showed resistance to midge both under natural infestation a nd no-choice headcage screening at ICRISTAT Center, India, over four season s, 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 m oderate levels of resistance to both midge and leaf diseases at Alupe, Keny a; and these lines can be used as sources of multiple resistance to these p ests. Lines IS 2766, IS 7148, IS 8733, and IS 8589, showed high levels of r esistance to leaf diseases in Kenya. Resistance to midge breaks down in som e lines at Alupe, Kenya; possibly because of the influence of environment o n the expression of resistance or the possible differences in midge populat ions at different geographic locations. (C) 1999 Published by Elsevier Scie nce Ltd. All rights reserved.