Risk analysis of yield losses caused by rice leaf blast associated with temperature changes above and below for five Asian countries

Risks of yield loss caused by rice blast associated with global temperature changes for five Asian countries were studied with a combined model (Coupling of CERES-Rice with BLASTSIM). Historical daily weather data (at least five years) were collected from 53 locations in 5 Asian countries. Two weather generators, WGEN and WMAK, from the Decision Support System for Agrotechnology Transfer (DSSAT) were used to produce estimated daily weather data for each location. Effects of global temperature change on rice leaf blast epidemics causing yield losses were studied using simulations. Estimated yield losses caused by leaf blast from thirty years of simulations were statistically analyzed. Effects of temperature change on yield loss caused by blast epidemics were compared statistically. Concepts of YL50, YL70 and YL90, representing the cumulative probabilities of 50%, 70% and 90% of yield loss, respectively, were introduced and applied to assess the risk of yield loss caused by leaf blast associated with each temperature change for each location. At most locations, temperature change had significant effects on blast development causing yield loss. In cool sub-tropical zones such as Japan and northern China, elevation of ambient temperature resulted in a higher risk of yield loss. In warm humid sub-tropics and humid tropics such as southern China, Philippines and Thailand, lower temperature led to a higher risk of yield loss, and higher temperature decreased yield losses at some locations in these areas. YL90 values were presented for each location as reference of disease control. (C) 1998 Elsevier Science B.V.