SCREENING OF COTTON GERMPLASM AGAINST COTTON LEAF CURL VIRUS

Cotton leaf curl virus poses a major threat to cotton productivity in Pakistan. Screening of germplasm to explore resistant source is a basic step towards the solution of this hazardous problem. With this objective genetic material comprising 11060 genotypes of cotton of different research centers was tested at Cotton Research Station, Vehari during 2002 to 2007. During 2002-03, 3694 genotypes were tested on the basis of cotton leaf curl virus disease incidence and 30 (Code No./varieties 124, 141, 170, 185, 218, 244, 252, 338, FVH-153, VH-176, 609, 721, 723, 724, 752, 834, 891, 918, 1018, 106, 111, 114, 115, 141, 156, 160, 175, 178, 183, 253) lines showed no symptoms of this disease. Out of 2792 genotypes screened during 2003-04, 7 (Code No./varieties 124, 170, 244, 252, VH-176, VH-209, 609) were found virus free. During next three years i.e., 2004 to 2006, all the genotypes (4364) showed susceptibility to cotton leaf curl virus disease. Two genotypes (China-1 and China-2) out of 210 tested during 2007 exhibited resistance to cotton leaf curl virus (CLCuV). 119 genotypes were screened on the basis of cotton leaf curl virus intensity during 2002-07, out of which 37 (Code No./varieties 654, 1050, 1411, 1448, 124, 141, 170, 185, 218, 244, 252, 338; 609, 721, 723, 724, 752, 834, 891, 918, 1018; NIBGE-106, NIBGE 111, NIBGE 114, NIBGE-115, NIBGE 141, NIBGE156, NIBGE160, NIBGE 175, NIBGE 178, NIBGE 183, NIBGE 253, FVH-153, VH-176, VH-209, China-1, China-2) lines were found virus free. Twenty four lines were tested against Cotton Leaf Curl Virus on the basis of sick plot technique during 2002-07. Among these lines 609 from Cotton Research Station Multan, 3232 from Central Cotton Research Institute Multan, VH-156 from Cotton Research Station Vehari, China-14 from Nanjing Agri. University China showed minimum disease incidence 0.8%, 7.6%, 14.75% and 23.5%, respectively. The results of recent research demonstrated that it is possible to explore resistant material from germplasm through screening on the basis of incidence and intensity. The same can be utilized in the breeding programme for evolving CLCuV tolerant/resistance verities of cotton.