Effect of drought on isoprene emission rates from leaves of Quercus virginiana Mill

• Published in: Atmospheric environment (1994) Vol. 38; no. 36; pp. 6149 - 6156
• Main Authors: Pegoraro, E., Rey, A., Greenberg, J., Harley, P., Grace, J., Malhi, Y., Guenther, A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-11-2004; Elsevier Science
• Subjects: Applied sciences; Atmospheric pollution; Dispersed sources and other; Exact sciences and technology; Leaf water potential; Live oak; Photosynthesis; Pollution; Pollution sources. Measurement results; Stomatal conductance; Water-stress; Leaf water potential; Water-stress; Photosynthesis; Stomatal conductance; Live oak; Natural origin pollution; Hydrocarbon; Troposphere; Volatile organic compound; Plant leaf; Fagaceae; Pollutant emission; Water stress; Biogenic factor; Air biosphere interaction; Dicotyledones; Angiospermae; Air pollution; Spermatophyta; Isoprene
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2004.07.028

Leaf isoprene emission rates (
F
iso) were studied in 2-year old trees of live oak (
Quercus virginiana Mill.) during two drying–rewatering cycles. During the first drying–rewatering cycle, photosynthesis (
A) and stomatal conductance (
g
s) decreased by 92%(±7%) and 91%(±8%), respectively, while
F
iso remained essentially constant for 8 days of treatment. After 12 days under severe drought conditions,
F
iso was reduced by 64%(±6%). Similar values were found during the second drying–rewatering cycle. During the recovery phase of both cycles,
F
iso recovered more quickly than
A and
g
s. The lower drought sensitivity of
F
iso compared with that of
A resulted in a higher percentage of fixed C lost as isoprene (
C
iso/
C
A
) as plants became more stressed, reaching peaks of 50% when
A was almost zero.
F
iso showed a strong negative linear relationship with pre-dawn leaf water potential (
ψ
PD) that could be a useful parameter to include in isoprene emission models to account for effects of drought stress on leaf
F
iso.