Simulation studies on epidemics of wheat stripe rust (Puccinia striiformis) on slow-rusting cultivars and analysis of effects of resistance components

Simulation studies were conducted to analyse the effects of components of slow-rusting resistance to stripe rust ( Puccinia striiformis ) on wheat varieties using the Slow-Rusting Epidemic Simulation Model (SRESM). Five components, infection efficiency (IE), sporulation capacity (SC), lesion expansion rate (LE), latent period (LP) and infectious period (IP) were studied for their importance in epidemics under various weather and pathogen inoculum conditions. Simulation outputs were analysed statistically. The LE, IE and SC were found to be the most important components. However, final disease was more strongly influenced by weather and initial disease. The Integrated Resistance Index (IRJ), which combines the effects of resistance components, was used to predict the effects of various combinations of components in different types of weather and at different levels of initial disease intensity. These predictions provide guidelines for plant breeders and are useful in selecting varieties for specific regions.