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Physiological effects of long‐term exposure to low and moderate concentrations of atmospheric NH 3 on poplar leaves
Author(s) -
HOVE L. W. A.,
KOOTEN O.,
ADEMA E. H.,
VREDENBERG W. J.,
PIETERS G. A.
Publication year - 1989
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1989.tb01969.x
Subject(s) - transpiration , stomatal conductance , photosynthesis , chlorophyll fluorescence , chemistry , horticulture , guard cell , shoot , fumigation , botany , respiration , chlorophyll , biology
. Poplar shoots ( Populus euramericana L.) obtained from cuttings were exposed for 6 or 8 weeks to NH 3 concentrations of 50 and 100 μgm −3 or filtered air in fumigation chambers. After this exposure the rates of NH 3 uptake, transpiration, CO 2 assimilation and respiration of leaves were measured using a leaf chamber. During the long‐term exposure also modulated chlorophyll fluorescence measurements were carried out to obtain information about the photosynthetic performance of individual leaves. Both fluorescence and leaf chamber measurements showed a higher photosynthetic activity of leaves exposed to 100 μg NH 3 m −3 . These leaves showed also a larger leaf conductance and a larger uptake rate of NH 3 than leaves exposed to 50 μg m −3 NH 3 or filtered air. The long‐term NH 3 exposure did not induce an internal resistance against NH 3 transport in the leaf, nor did it affect the leaf cuticle. So, not only at a short time exposure, but also at a long‐term exposure NH 3 uptake into leaves can be calculated from data on the boundary layer and stomatal resistance for H 2 O and ambient NH 3 ‐concentration. Furthermore, the NH 3 exposure had no effect on the relation between CO 2 ‐assimilation and stomatal conductance, indicating that NH 3 in concentrations up to 100 μg m −3 has no direct effect on stomatal behaviour; for example, by affecting the guard or contiguous cells of the stomata.