The influence of ozone and nutrition on ?13C in Betula pendula

Abstract

In the cellulose of stems and leaves, δC was investigated in a birch clone (Betula pendula), which was exposed throughout the growing season to either <3 (control) or 90/40 nl O 1 (day/night). Each regime was split into plants under high or low nutrient supply. δC was increased (becoming less negative), in stems rather than leaves, by both high nutrition (+2‰) and O stress (+1‰). Whereas high nutrition raised the wateruse efficiency (WUE) while lowering the CO concentration in the inner leaf air space (c ), WUE decreased and c increased under O stress. Therefore, only the nutritional effect on the carbon isotope fractionation was reproduced by the model of Farquhar et al. (1982) which estimates WUE by means of δC based on c . c was not biased by 'patchiness' in respect to stomatal opening. The latter was verified by microscopical analysis and the complete water infiltration of the birch leaves through the stomata, independent of the diurnal course of the leaf conductance for water vapour. Under low nutrient supply, the activity of phosphoenol pyruvate carboxylase (PEPC) was roughly doubled by ozone to about 1.3% of the total carboxylation capacity (by PEPC + rubisco), and was increased to 1.7% under high nutrition. The fractionation model, extended to account for varying activities of the carboxylating enzymes, indicated that stimulated PEPC was the cause of elevated δC, although c was increased under O stress. The stimulation of PEPC and, as a consequence, elevated δC are discussed as part of a whole-plant acclimation to O stress.

Reconstructing Atmospheric CO2Concentration Using Its Relationship with Carbon Isotope Variations in Annual Tree Ring of Red Pine

“…Cair and Ci/Ca on δ C of tree rings have been shown to be correlated with temperature and precipitation (Edwards et al, 2000), and air pollutants (Heaton and Crossley, 1995;Saurer et al, 1995;Sakata and Suzuki, 2000). In the present study, slight increase in δ attributed to the effect of other environmental conditions on carbon isotope discrimination although the mechanism remains unclear.…”

Ozone‐induced accumulation of carbohydrates changes enzyme activities of carbohydrate metabolism in birch leaves

“…Birch plants (Betula pendula Roth) were grown from cuttings in the Birmensdorf field fumigation chambers (Landolt, Pfenninger & Liithy-Krause, 1989;Saurer et al, 1995) in a sand-culture system with two different concentrations of a commercial fertilizer (high fertilization (HF), 0-05%; or low fertilization (LF), 0-005 % ; corresponding to 6-5 mM N or 0-65 mM N, respectively) which contained macronutrients and micronutrients balanced in an optimal range (see Landolt et al, 1997). Plants in both fertilization treatments were exposed to charcoal-filtered air (controls) or charcoal-filtered air enriched by ozone (O3): 40 nl T'O3 from 2100 to 0700 hours and 90 nl T^ O3 from 0700 to 2100 hours in the fumigation chambers, from early May until mid-September.…”

“…Plants in both fertilization treatments were exposed to charcoal-filtered air (controls) or charcoal-filtered air enriched by ozone (O3): 40 nl T'O3 from 2100 to 0700 hours and 90 nl T^ O3 from 0700 to 2100 hours in the fumigation chambers, from early May until mid-September. Details of plant culture and the fumigation system were described by Landolt et al (1989) and Saurer et al (1995).…”

Adverse effects of ambient ozone on watermelon yield and physiology at a rural site in Eastern Spain

“…The mechanisms underlying the O $ -induced disparity between measured and theoretically predicted c i \c a remain to be established. However, enhanced stomatal heterogeneity or patchy stomatal closure and\or differences in time-integration scale appear not to explain the observed discrepancies between predicted and measured c i values in O $ -treated leaves (Saurer et al, 1995 ;Zheng et al, 1998a). Current studies are focusing on alterations in mesophyll conductance and the contribution of non-Rubisco carboxylases to the shift in ∆ of O $ -treated leaves.…”