SIMULATION STUDIES ON EPIDEMICS OF WHEAT STRIPE RUST (PUCCINIA-STRIIFORMIS) ON SLOW-RUSTING CULTIVARS AND ANALYSIS OF EFFECTS OF RESISTANCECOMPONENTS

Simulation studies were conducted to analyse the effects of components of slow-rusting resistance to stripe rust (Puccinia striiformis) on w heat varieties using the Slow-Rusting Epidemic Simulation Model (SRESM ). Five components, infection efficiency (IE), sporulation capacity (S C), lesion expansion rate (LE), latent period (LP) and infectious peri od (IF) were studied for their importance in epidemics under various w eather and pathogen inoculum conditions. Simulation outputs were analy sed statistically. The LE, IE and SC were found to be the most importa nt components. However, final disease was more strongly influenced by weather and initial disease. The Integrated Resistance Index (IRI), wh ich 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 s electing varieties for specific regions.