XVI International Botanical Congess

Isoprene, a hydrocarbon emitted from the leaves of many plants, has a large impact on atmospheric chemistry. A plant's capacity for isoprene emission is defined as the rate of emission at 30 degrees C and 1/2 full sunlight (known as the basal rate). Analysis of three years of field data from a single tree showed that the basal rate may be related to previous weather conditions. We grew plants in temperature controlled greenhouses under four conditions (two light levels in two temperatures) then moved plants between the four conditions. We found that the basal rate in warm or sunny growth conditions was twice the basal rate in cold or shaded growth conditions. In warm and sunny conditions, the basal rate was nearly four times the rate in cold and shaded conditions. The basal rate changed to the new level within 5-30 hrs after being moved into a new condition. This work was supported by the USDA.