Development of screening techniques and identification of new sources of resistance to Ascochyta blight disease of chickpea

Effective controlled-environment and field screening techniques were developed and refined to identify resistance to Ascochyta blight (AB), caused by Ascochyta rabiei (Pass.) Labr. in chickpea. A controlled environment plant growth room facility developed for AB evaluation at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India was modified to evaluate chickpea genotypes for resistance to AB. Controlled environment screening techniques, such as a seedling screening technique using 10-day-old seedlings and cut-twig screening techniques using excised twigs (10-15 cm long) were developed. Components of the screening techniques were optimized in the controlled environment-plant growth room. The controlled environment screening techniques were found to be rapid, reliable and reproducible and a positive correlation was found between the seedling and cut-twig screening techniques (r=0.94). The cut-twig screening technique was quicker than the seedling screening technique and is particularly useful in screening segregating breeding lines derived from wild Cicer spp. Results of the controlled environment screening techniques were compared with results of field screening trials carried out at Dhaulakuan and Ludhiana in India, where the pathogen is endemic. A significant positive correlation was found between results from the controlled environment and field screening techniques (r=0.88). Using these resistance screening techniques, 150 elite chickpea breeding lines were evaluated and 29 lines with high and stable resistance to AB were identified.