ISSN:
1365-3040
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Abstract. Poplar shoots (Populus euramericana L.) obtained from cuttings were exposed for 6 or 8 weeks to NH3 concentrations of 50 and 100 μgm−3 or filtered air in fumigation chambers. After this exposure the rates of NH3 uptake, transpiration, CO2 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 NH3 m−3. These leaves showed also a larger leaf conductance and a larger uptake rate of NH3 than leaves exposed to 50 μg m−3 NH3 or filtered air. The long-term NH3 exposure did not induce an internal resistance against NH3 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 NH3 uptake into leaves can be calculated from data on the boundary layer and stomatal resistance for H2O and ambient NH3-concentration. Furthermore, the NH3 exposure had no effect on the relation between CO2-assimilation and stomatal conductance, indicating that NH3 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3040.1989.tb01969.x
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