MICROCLIMATE IN OPEN-TOP CHAMBERS - IMPLICATIONS FOR PREDICTING CLIMATE-CHANGE EFFECTS ON RICE PRODUCTION

A new open-cop chamber (OTC) system, designed to maintain increased CO 2 concentration and temperature, was verified to generate abiotic micr oenvironment closely approximating that in the natural environment of flooded rice under field conditions in the tropics. Although field tes ts demonstrated that the system could set and control temperature and CO2 to +/-10% precision for >90% of the time, changes in chamber micro environment conditions that could influence crop growth and developmen t did occur The primary changes in microclimate between chamber and op en field were in light transmission (9%) and higher night temperature within the chambers. These differences contributed to 12% reduction in vegetative and reproductive yields inside the chamber compared with t hat under field conditions. Data from the microclimate assessment sugg est that the plant response should be corrected accordingly to approxi mate the climate change response of rice. This is essential to improve the efficiency of model predictions based on experiments conducted th rough the OTC approach.