The effects of global temperature change on rice leaf blast epidemics: a simulation study in three agroecological zones

A combined simulation model (CERES-Rice coupled with BLASTSIM) was used to study the effects of global temperature change on rice leaf blast epidemics in several agroecological zones in Asia. At least five years of historical daily weather data were collected from each of 53 locations in five Asian countries (Japan, Korea, China, Thailand and Philippines). Two weather generators, WGEN and WMAK, from the Decision Support System for Agrotechnology Transfer (DSSAT), were utilized to produce estimated daily weather data for each location. Thirty years of daily weather data produced by one of the generators for each location were used as input to the combined model to simulate blast epidemics for each temperature change. Maximum blast severity and the area under the disease progress curve (AUDPC) caused by leaf blast resulted from 30-yr simulations were statistically analyzed for each temperature change and for each location. Simulations suggest that temperature changes had significant effects on disease development at most locations. However, the effect varied in different agroecological zones. In the cool subtropics such as Japan and northern China, elevation of temperature above normal temperature resulted in more severe blast epidemics. In warm/cool humid subtropics, elevation of temperature caused significantly less blast epidemics. However, lower temperature caused insignificant difference in disease epidemics compared with that in normal temperature. Conditions in the humid tropics were opposite to those in cool areas, where daily temperature changes by -1 degrees C and -3 degrees C resulted in significantly more severe blast epidemics, and temperature changes by +1 degrees C and +3 degrees C caused less severe blast. Scenarios showing blast intensity as affected by temperature change in different agroecological zones were generated with a geographic information system (GIS). (C) 1998 Elsevier Science B.V.