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Physiological effects of long term exposure to low concentrations of SO 2 and NH 3 on poplar leaves
Author(s) -
Hove L. W. A.,
Kooten O.,
Wijk K. J.,
Vredenberg W. J.,
Adema E. H.,
Pieters G. A.
Publication year - 1991
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1991.tb02899.x
Subject(s) - stomatal conductance , chemistry , fumigation , photosynthesis , shoot , conductance , horticulture , respiration , botany , cuticle (hair) , biology , biochemistry , mathematics , genetics , combinatorics
Shoots of poplar ( Populus euramericana L. cv. Flevo) were exposed to filtered air, SO 2 , NH 3 or a mixture of SO 2 and NH 3 for 7 weeks in fumigation chambers. After this exposure gas exchange measurements were carried out using a leaf chamber. As compared to leaves exposed to filtered air, leaves pretreated with 112 μg m −3 SO 2 showed a small reduction in maximum CO 2 assimilation rate (P max ) and stomatal conductance (g s ). They also showed a slightly higher quantum yield and dark respiration. In addition, the fluorescence measurements indicated that the Calvin cycle of the leaves pretreated with 112 μg m −3 SO 2 was more rapidly activated after transition from dark to light. An exposure to 64 μg m −3 NH 3 had a positive effect on P max , stomatal conductance and NH 3 uptake of the leaves. This positive effect was counteracted by an SO 2 concentration of 45 μg m −3 . The exposure treatments appeared to have no effect on the relationship between net CO 2 ‐assimilation and g s . Also, no injury of the leaf cuticle or of epidermal cells was observed. Resistance analysis showed that NH 3 transfer into the leaf can be estimated from data on the boundary layer and stomatal resistance for H 2 O transfer and NH 3 concentration at the leaf surface, irrespective of whether the leaves are exposed for a short or long time to NH 3 or to a mixture of NH 3 and SO 2 . In contrast SO 2 uptake into the leaves was only partly correlated to the stomatal resistance. The results suggest a large additional uptake of this gas by the leaves. The possibility of a difference in path length between SO 2 and H 2 O molecules is proposed.