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- Piikki, Kristin, 1975, et al.
(författare)
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The grain quality of spring wheat (Triticum aestivum L.) in relation to elevated ozone uptake and carbon dioxide exposure
- 2008
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Ingår i: European Journal of Agronomy. - : Elsevier BV. - 1161-0301. ; 28:3, s. 245-254
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Tidskriftsartikel (refereegranskat)abstract
- Ozone (O-3) and carbon dioxide (CO2) effects on the quality of spring wheat (Triticum aestivum L.) were evaluated. The dataset originated from 13 European open-top chamber experiments, including three countries, 10 years and four cultivars. The O-3 exposure significantly reduced the protein yield, even though the grain protein concentration (GPC) was increased and tended to increase the Zeleny value and the Hagberg falling number. These variables reached values representing enhanced grain maturity after elevated 03 exposure, possibly explained by O-3 induced early senescence. The CO2 elevation was demonstrated to increase the protein yield but reduce the GPC and the Zeleny value. Both O-3 and CO2 were demonstrated to affect wheat grain yield (GY) but by different means; O-3 reduced GY (P<0.001) mainly by limiting the 1000-grain weight, while CO2 enhanced GY (P < 0.01) mainly by increasing the number of grains produced per unit ground area. Two earlier used O-3 indices, the accumulated stomatal uptake of O-3 above a flux threshold of 6 nmol m(-2), s(-1) (AF(st)6), and the accumulated O-3 dose above a concentration threshold of 40 nmol mol(-1) (AOT40), were employed in parallel in the derivation of dose-response relationships with all investigated variables (GY, number of grains per unit area, 1000-grain weight, protein yield, GPC, Zeleny value, wet gluten, dry gluten, starch concentration, Hagberg falling number, specific weight and water quotient). The uptake-based index (AF(st)6) tended to better explain variation in the response variables and yielded dose-response regressions of a higher statistical quality than did the external-dose index (AOT40). Based on an independent subset of the present data, the validities of (1) a negative linear relationship between GPC and GY and (2) a positive but decelerating relationship between protein yield and GY including both O-3 and CO2 treatments were tested and confirmed. (c) 2007 Elsevier B.V. All rights reserved.
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| 2. |
- Pleijel, Håkan, 1958, et al.
(författare)
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Relationships between ozone exposure and yield loss in European wheat and potato - a comparison of concentration- and flux-based exposure indices
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:15, s. 2259-2269
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Tidskriftsartikel (refereegranskat)abstract
- Data from open-top chamber experiments with field grown crops, performed in Sweden, Finland, Belgium, Italy and Germany, were combined to derive relationships between yield and ozone exposure for wheat (Triticum aestivum L.) and potato (Solanum tuberosum L.). Three different exposure indices were compared: AOT40 (accumulated exposure over a threshold ozone concentration of 40 nmol mol(-1)), CUOt (cumulative stomatal uptake of ozone, using a constant ozone uptake rate threshold of t nmol m(-2) s(-1)) and mAOTc(0) (conductance modified AOT using a threshold concentration for ozone of c(0) nmol mol(-1)). The latter is essentially a combination of AOT and CUO. Ozone uptake was estimated using a Jarvis-type multiplicative model for stomatal conductance. In terms of correlation between relative yield (RY) and ozone exposure, CUO5, the CUO index with an ozone uptake rate threshold of 5 nmol m(-2) s(-1), performed best for both wheat and potato, resulting in r(2) values of 0.77 and 0.64, respectively. CUO5 performed considerably better in terms of the correlation between RY and ozone exposure, than AOT40 for wheat, while mAOT10, the best performing mAOT index in this case, was intermediate in performance for this crop. For potato, the differences between the different ozone exposure indices AOT40, CUO5 and mAOT20 (the mAOT index performing best for potato) in the correlation between RY and ozone exposure were relatively small. To test the assumption that the non-stomatal deposition of ozone was negligible for the uppermost, sunlit leaves, measurements of ozone uptake in relation to leaf conductance for water vapor of wheat leaves in a cuvette system were used. The non-stomatal deposition of ozone to the leaves turned out to be comparatively small. Based on the non-stomatal conductance (g(ns) = 15 mmol m(-2) s(-1)) estimated for the wheat leaves in the cuvette system, it was concluded that the consequence of omitting the non-stomatal conductance is small. In conclusion the study indicated that the ozone uptake based approach showed a high degree of fitting along a north-south European transect of pedoclimatic conditions, and represents a better and more relevant approach to the quantification of ozone effects on crops growth than the use of ozone exposure indices purely based on ozone concentrations. (C) 2004 Elsevier Ltd. All rights reserved.
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