Characterization of exotic germplasm lines for resistance to wheat rusts and spot blotch

Breeding resistant varieties of wheat is a continuous process and empirical disease control depends on deployment of diverse sources of genetic resistance to the deadly rusts. A total of 166 exotic wheat germplasm accessions were evaluated for resistance to wheat rusts having some component of resistance to either any of the three rusts and spot blotch. The data for adult plant resistance (APR) on leaf and stem rusts, was recorded at Wellington while yellow rust epiphytotic was artificially created at Karnal for identification of resistant lines. Based on APR data 85, 96 and 16 accessions were found completely resistant to leaf, stem and stripe rusts respectively. Based on the seedling resistance data against different pathotypes (10 each for leaf and stripe and 5 for stem rust) of each rust, nine, fifteen and five accessions were found highly resistant respectively. Based on the multi-environment adult plant resistance data and race specific seedling data, we were able to identify 28, accessions highly resistant to either one or two rusts. For spot blotch the evaluation was done at hotspot locations Wadura and Coochbehar and 26 accessions were found to be highly resistant against this disease. The lines so identified in this study are being used in the hybridization programs to enhance the levels of resistance.