Effects of temperature and light intensity on isoprene emission of Edgeworthia chrysantha

Abstract

Isoprene is a major compound emitted by plants. Effects of light and temperature on isoprene emission rate (E) of Edgeworthia chrysantha was investigated. A leaf cuvette was modified to collect volatiles emitted by the plant leaf and its photosynthetic rate (A) and E were determined for the same periods. The experimental results showed that E value increased with increases in photosynthetic photon flux (PPF) and leaf temperature up to 40°C. A change in A value against PPF was similar to the change in E, but, for leaf temperature, the A value had a maximum between 25 and 30°C. As a result, carbon ratio of isoprene emission to photosynthetic uptake increased greatly with an increase in leaf temperature and had the highest value of 1-5% at 40°C. A model (G93) was employed to explain the plant isoprene emission responses to PPF and leaf temperature. The model could explain the isoprene emission within the RMS error of 3 nmol m-2s-1, while emission factor e calculated for standard conditions of 1000μmol m-2s-1 PPF and 30°C leaf temperature was largely different between measurements. This suggests that determining representative e value for a whole plant and stands is essential to estimate a regional scale isoprene emission. © 2005, The Society of Agricultural Meteorology of Japan. All rights reserved.