Pathogenic variability of Ascochyta rabiei causing blight of chickpea in India

Ascochyta blight caused by Ascochyta rabiei (Pass.) Labr. is one of the major disease of chickpea worldwide. Since there is report of variable number of races an attempt was made to investigate the pathogenic variability and identify the existing race(s) of A. rabiei, which will be helpful in improving/breeding resistant variety of chickpea. The virulence of 25 isolates of A. rabiei from different parts of India were analysed on 10 differential genotypes showing different levels of resistant and susceptible reactions under artificial inoculation in controlled environment. Based on the reactions, the population of A. rabiei were grouped into seven races using 1-9 rating scale. The genotype ICC 4991 showed susceptible reaction against all the isolates of the pathogen. Five genotypes, ICC 11879, ICC 3996, ICC 15978, GL 26054 and H00 108 exhibited resistant to moderately resistant reactions against the isolates of A. rabiei. Distribution of races was mapped. Race 1 is widely prevalent in 5 states namely, Delhi, Himachal Pradesh and Jammu and Kashmir whereas, the most virulent is race 7 found in Uttar Pradesh. This study standardized a set of differential genotypes of chickpea for race identification and established 7 races of Ascochyta rabiei. The race determination of A. rabiei would be helpful in improving/breeding resistant chickpea variety. The information is entirely new in respect of differential genotypes and distribution pattern of races of A. rabiei in India.