Comparison of resistance to cotton leaf curl disease (Multan/Burewala) in Gossypium hirsutum L. Varieties and breeding lines

Twenty-four cotton varieties and advance breeding lines were evaluated for their resistance to cotton leaf curl disease (CLCuD; Multan/Burewala) under natural field and in glasshouse conditions for two consecutive years. Resistance was based on symptom expression and disease severity index. All the cotton genotypes exposed to the vector whitefly in the field and artificially infected by grafting manifested a high level of resistance against CLCuD (Multan) with the exception of genotype NIAB-999 that was moderately resistant. All the test varieties/breeding lines were highly susceptible to CLCuD (Burewala) both in the field and the glasshouse. However, substantial differences were noted between genotypes for disease index under field conditions. Graft inoculation studies showed that all genotypes inoculated with CLCuD (Burewala) developed disease within 9-13 days whereas those graft-inoculated with CLCuD (Multan) developed symptoms from 15 to 22 days after grafting. Severe reduction occurred in plant morphology, fibre and yield parameters of cotton variety NIAB-111 following inoculation with CLCuD (Burewala) as compared with CLCuD (Multan).