| 1. |
- Karlsson, Per Erik, 1957, et al.
(author)
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A cumulative ozone uptake-response relationship for the growth of Norway spruce saplings
- 2004
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In: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 128:3, s. 405-417
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Journal article (peer-reviewed)abstract
- Norway spruce saplings [Picea abies (L.) Karst.] were exposed during four growing seasons to different ozone treatments in open-top chambers: charcoal filtered air (CF), non-filtered air (NF) and non-filtered air with extra ozone (NF+, 1.4xambient concentrations). The CF and NF + ozone treatments were combined with phosphorous deficiency and drought stress treatments. The total biomass of the trees was harvested at different intervals during the experimental period. The ozone uptake to current-year needles of the Norway spruce saplings was estimated using a multiplicative stomatal conductance simulation model. There was a highly significant correlation between the reduction of total biomass and the estimated cumulative ozone uptake, which did not vary when different thresholds were applied for the rate of ozone uptake. The reduction of the total biomass was estimated to 1 per 10 mmol m(-2) cumulated ozone uptake, on a projected needle area basis. (C) 2003 Elsevier Ltd. All rights reserved.
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| 2. |
- Karlsson, Per Erik, 1957, et al.
(author)
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Impact of ozone on the growth of birch (Betula pendula) saplings
- 2003
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In: Environmental Pollution. - 0269-7491. ; 124:3, s. 485-495
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Journal article (peer-reviewed)abstract
- Saplings of one half-sib family of birch, Betula pendula, were exposed to three levels of ozone in open-top chambers (OTCs) during two growing seasons 1997-1998. The ozone treatments were non-filtered air (NF, accumulated daylight AOT40 over the two growing seasons of 3.0 mul l(-1) h), non-filtered air with extra ozone (NF +, accumulated daylight AOT40 of 27.3 mul l(-1) h) and nonfiltered air with additional extra ozone (NF++, accumulated daylight AOT40 of 120 mul l(-1) h), The birch saplings, including the roots, were harvested after the first and second growing seasons. After the first growing season, the NF++ treatment reduced the total wood biomass by 22%, relative to the NF treatment. There was no further reduction of the total wood biomass in the NF++ treatment after the second growing season. The root biomass was reduced by 30% after the first growing season. The shoot/root ratio, as well as the proportional biomass of leaves, were increased by ozone during both years. The ozone impact on the relative growth rate was estimated to -2% per 10 mul l(-1) h daylight AOT40 per growing season. (C) 2003 Elsevier Science Ltd. All rights reserved.
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| 3. |
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| 4. |
- Piikki, Kristin, 1975, et al.
(author)
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The impact of tropospheric O3 on leaf number duration and tuber yield of the potato (Solanum tuberosum L.) cultivars Bintje and Kardal
- 2004
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In: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 0167-8809. ; 104:3, s. 483-492
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Journal article (peer-reviewed)abstract
- Ozone (O3) is a major phytotoxic air pollutant with the potential to cause severe yield losses in potato (Solanum tubersosum L.) and in other crops. The present study was aimed (i) to investigate the O3 sensitivity of two potato cultivars (Bintje and Kardal) in relation to their earliness in maturation, and (ii) to analyse possible O3 effects on potato tuber dry mass (DM) production in relation to leaf duration. The experiment was performed in the southwest of Sweden using open-top chamber (OTC) technique. The crops were exposed to three levels of O3: charcoal-filtered air (CF), non-filtered air (NF) and non-filtered air + 26 nmol mol−1 O3 (NF+). In addition, ambient air plots were used to monitor the impact of the OTC enclosure. Leaf number duration (LND) was calculated as the number of leaves integrated over the temperature sum accumulation during the season. In the present study, the O3 effects on potato were characterised by visible injury of the leaves and earlier leaf senescence. The haulm/plant DM ratio was significantly lower in NF+ compared to CF and NF. The conclusions were (i) that the early to intermediate maturing cultivar Bintje tended to suffer more from O3 injury than the late maturing cultivar Kardal, (ii) that this was due to a difference in the ability to compensate for haulm damage by the development of new leaves rather than to a difference in leaf O3 sensitivity, and (iii) that a rather low O3 exposure can induce a significant reduction in LND in potato. The O3 effects on tuber DM (−2% in NF+ and +31% increase in CF, both compared to NF) could not be statistically demonstrated, although there was a strong correlation between LND and tuber DM.
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| 5. |
- Pleijel, Håkan, 1958, et al.
(author)
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Differential ozone sensitivity in an old and a modem Swedish wheat cultivar - grain yield and quality, leaf chlorophyll and stomatal conductance
- 2006
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In: Environmental and Experimental Botany. - : Elsevier BV. - 0098-8472. ; 56:1, s. 63-71
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Journal article (peer-reviewed)abstract
- Field-grown crops of one modem ('Dragon') and one 100-year old ('Lantvete') wheat (Triticum aestivum L.) cultivar were exposed to charcoal-filtered air (CF) or non-filtered air plus additional ozone (NF+) in open-top chambers (n = 6). Ambient air plots (11 = 3) were used to monitor the effects of the chamber enclosure. Quantitative (ear weight, harvest index and 1000-grain weight), as well as qualitative (grain concentration of N. P. K, Ca, Mg, Cd), aspects of crop yield were studied. In addition, the chlorophyll content of the top leaf was followed during the 10-week-long ozone exposure and flag leaf stomatal conductance was monitored. Ear weight was negatively affected by ozone. The effect was smaller in the lower yielding 'Lantvete' compared to the modem cultivar 'Dragon'. A similar ozone effect was found for the harvest index and 1000-grain weight. The difference between cultivars was small for 1000-grain weight, with harvest index significantly lower in 'Lantvete' compared with 'Dragon'. The crude protein concentration of the grain was higher in 'Lantvete', and was enhanced by ozone exposure. No significant treatment or cultivar effects were observed on grain Ca and Cd concentrations, but the greatest chamber effect was on Cd, which was considerably higher in grain from treatment chambers compared with ambient air (possibly due to the higher rate of transpiration in the plants enclosed in the chambers). There were strong differences with respect to grain P, K and Mg concentration between cultivars; 'Lantvete' exhibiting higher concentrations than 'Dragon' in all cases, apart from K. Weak, but significant, increases in grain P, K and Mg concentrations were evident in O-3-treated plants. The chlorophyll concentration of the flag leaf was negatively affected by ozone exposure after approximately I month, but chlorophyll content declined faster in 'Dragon' than 'Lantvete'. Flag leaf chlorophyll concentration was significantly lower in 'Lantvete' compared with 'Dragon' before onset of ozone effects in NF+ and during most of the experiment in CF. Stomatal conductance was also significantly lower in 'Lantvete' than in 'Dragon'. The most important conclusion drawn from the present study is that the 'older' cultivar, 'Lantvete', was less affected by ozone than the modem, bred cultivar, 'Dragon'. This observation might to a large extent be explained by the higher stomatal conductance exhibited by the modern wheat cultivar. The result is consistent with earlier investigations for Greek wheat cultivars, and suggests that the findings reported by others, based on vegetative growth, may extend to grain yield. Growth dilution effects (i.e. the lower observed concentration of an element at higher biomass yield) may explain observed differences between cultivars, and between ozone treatments, in the level of various elements, except for potassium. (c) 2005 Elsevier B.V. All rights reserved.
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| 6. |
- Skarby, L., et al.
(author)
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Growth of Norway spruce (Picea abies) in relation to different ozone exposure indices: a synthesis
- 2004
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In: Atmospheric Environment. - 1352-2310. ; 38:15, s. 2225-2236
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Journal article (peer-reviewed)abstract
- In the Goteborg Ozone-Spruce Project (GOSP), two independent open-top chamber experiments were conducted during four growing seasons, using one clone of Norway spruce (Picea abies). The experiments tested the impact of ozone, alone and in combination with low phosphorus supply and in combination with drought stress, respectively, on biomass accumulation. In this paper, the results from both experiments were combined for the first time in order to analyse the relationship between relative biomass accumulation and different exposure indices (accumulated exposure over a threshold (AOT) with different cut-off concentrations, and the sum of ozone concentrations above 60 nl l(-1), referred to as SUM06). In addition, a pooled analysis was made on several European studies of Norway spruce as a first effort to synthesize independent data and test the relative growth in relation to the AOT40 index. Significant negative relationships between the relative biomass of the GOSP-clone and the different indices were obtained. AOT20 and AOT30 resulted in the highest correlations. Based on the regression model, ozone is predicted to reduce the biomass of the GOSP-clone by 1% at the critical level for forest trees in Europe, a seasonal AOT40 of 10 mul l(-1) h. A significant negative relationship between relative growth and AOT40 was obtained also with the European data set. At the present ozone critical level, the model predicted a 6% reduction in growth for the most sensitive Norway spruce trees in this data set. (C) 2004 Elsevier Ltd. All rights reserved.
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| 7. |
- Uddling, Johan, 1972, et al.
(author)
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Biomass reduction of juvenile birch is more strongly related to stomatal uptake of ozone than to indices based on external exposure
- 2004
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:28, s. 4709-4719
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Journal article (peer-reviewed)abstract
- In order to test the hypothesis that ozone-induced limitation of biomass production in juvenile silver birch (Betula pendula Roth) is driven by stomatal uptake of ozone (O-3) rather than external exposure, biomass reduction was related to the cumulative uptake of O-3 through stomata over an uptake cut-off threshold of x nmol O-3 m(-2) s(-1) (CUO > x), to the accumulated exposure to O-3 over a threshold of y nmol mol(-1) during daylight hours (daylight AOTy) or during 24 h (24 h AOTy), and to the sum of daytime concentrations exceeding 60 nmol mol(-1) (SUM06). The analysis included data from nine different experiments conducted in Sweden, Finland and Switzerland. Stomatal uptake of O-3 was estimated using a stomatal conductance (g,) model including g, response functions for photosynthetic photon flux density, water vapour pressure deficit of the air and air temperature. Experiment-specific maximum g(s) (g(max)) as well as g(s) in darkness (g(dark)) were assessed through local measurements. Biomass reduction Was more strongly related to CUO > x than to SUM06 and daylight or 24 h AOTy, but the difference between CUO > x and 24 h AOTy was small. The better performance of CUO > x was dependent on the use of site- and experiment-specific g(max) and g(dark) values, and there was a positive relationship between g(max) and biomass reduction per unit AOT40. Daylight AOTy and SUM06 could not account for the growth limiting impact of nocturnal O-3 uptake in the Swiss experiments. A sensitivity analysis revealed that the CUO > x estimates were largely insensitive to the estimate of the conductance for non-stomatal leaf surface deposition of O-3, as a result of turbulent conditions at the experimental plots. In summary, we conclude that CUO > x was more successful in accounting for the variation in biomass reduction in juvenile birch as compared to indices based on external exposure, if g(max) and g(dark) were locally parameterised. (C) 2004 Elsevier Ltd. All rights reserved.
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| 8. |
- Uddling, Johan, 1972, et al.
(author)
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Ozone impairs autumnal resorption of nitrogen from birch (Betula pendula) leaves, causing an increase in whole-tree nitrogen loss through litter fall
- 2006
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In: Tree Physiology. - 0829-318X. ; 26:1, s. 113-120
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Journal article (peer-reviewed)abstract
- Saplings of one half-sib family of birch, Betula pendula Roth, were exposed to three ozone concentrations (non-filtered air (NF); non-filtered air + 10-20 nmol O-3 mol(-1) (NF+); non-filtered air + 40-60 nmol O-3 mol(-1) (NF++)) in open-top chambers during two growing seasons from 1997 to 1998. Shed leaves were collected regularly during both growing seasons and, in 1998, the dry mass (DM) and nitrogen (N) concentrations ([N]) of the shed leaves were measured to quantify the total amount of N lost through litter fall. Dry mass and [N] were also determined in mid-August for attached, mature and non-senescent leaves, in order to estimate autumnal leaf N resorption efficiency and proportional leaf DM decrease. Net photosynthetic capacity was measured during August and September 1998, in a population of leaves that emerged in mid-July. Photosynthesis declined with increasing leaf age in the NF++ treatment, whereas it remained high throughout the measurement period in the NF and NF+ treatments. In both years, leaves abscised prematurely in the NF++ treatment, whereas this effect was only significant in 1998 in the NF+ treatment. There was a strong linear relationship between proportional leaf shedding and daylight ozone exposure above a threshold of 40 nmol mol(-1) (daylight AOT40) during the growing season. The resorption of N was significantly impaired by ozone, and the smaller autumnal decrease in leaf DM in elevated ozone concentrations suggested that the bulk resorption of leaf DM was also inhibited. Nitrogen resorption efficiencies were 81. 73 and 63% and leaf mass decreases were 45, 36 and 30% in the NF, NF+ and NF++ treatments, respectively. Compared with the NF treatment, total N loss through litter fall was increased by 16 and 122% in the NF+ and NF++ treatments, respectively. We conclude that ozone impaired N resorption from birch leaves before abscission, causing a substantial increase in whole-tree N loss through litter fall.
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| 9. |
- Uddling, Johan, 1972, et al.
(author)
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Source-sink balance of wheat determines responsiveness of grain production to increased [CO2] and water supply
- 2008
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In: Agriculture Ecosystems & Environment. - : Elsevier BV. - 0167-8809. ; 127:3-4, s. 215-222
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Journal article (peer-reviewed)abstract
- Manipulation of source (flag-leaf removal) and sink (ear trimming) was conducted in a factorial CO2-irrigation field chamber experiment with spring wheat (Triticum aestivum L.) in south-west Sweden to test the hypothesis that responsiveness of grain production and biomass partitioning to CO2 concentration ([CO2]) and water supply is dependent on the source-sink balance of the plant. Negative effects of doubled [CO2] on both individual grain mass (IGM) and harvest index (HI) were strongly related to decreasing relative sink strength (i.e. increasing source:sink ratio), probably as a result of feedbacks from sink limitation on source activity under elevated [CO2] being relatively more important as relative sink strength decreases. Substantial down-regulation of photosynthetic capacity in elevated [CO2], resulted in lack of significant stimulation of grain yield (GY) of unmanipulated shoots growing under elevated [CO2]. GY was even reduced by elevated [CO2] in sink-manipulated shoots, implying that high source:sink ratio may result in a down-regulation of photosynthetic capacity that more than offsets the direct stimulating effect of elevated [CO2]. High irrigation positively affected IGM and HI in source-manipulated shoots only, probably as a result of the timing of irrigation treatment effects on soil moisture during, but not before, grain filling. Irrigation thus probably affected source activity during grain filling rather than potential sink capacity determined before and around anthesis, an effect that should be more pronounced for shoots with low source:sink ratio. We conclude that effects of [CO2] and irrigation on grain production and biomass partitioning of wheat are strongly modified by source-sink balance of the plant, and that sink limitation is a major constraint on CO2-induced GY enhancement of spring wheat under Scandinavian climatic conditions. These findings may explain earlier observations of decreased CO2 responsiveness of GY in modern wheat cultivars, with lower whole-plant sink strength before and around anthesis compared to old cultivars, and call into question current attempts of molecular plant breeding to maximise photosynthetic activity before and around anthesis in order to enhance GY in a world with rising atmospheric [CO2]. (C) 2008 Elsevier B.V. All rights reserved.
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