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- Broberg, Malin, 1989, et al.
(author)
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Effects of elevated CO2 on wheat yield: Non-linear response and relation to site productivity
- 2019
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In: Agronomy. - : MDPI AG. - 2073-4395. ; 9:5
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Journal article (peer-reviewed)abstract
- © 2019 by the authors. Elevated carbon dioxide (eCO 2 ) is well known to stimulate plant photosynthesis and growth. Elevated carbon dioxide’s effects on crop yields are of particular interest due to concerns for future food security. We compiled experimental data where field-grown wheat (Triticum aestivum Linnaeus) was exposed to different CO 2 concentrations. Yield and yield components were analyzed by meta-analysis to estimate average effects, and response functions derived to assess effect size in relation to CO 2 concentration. Grain yield increased by 26% under eCO 2 (average ambient concentration of 372 ppm and elevated 605 ppm), mainly due to the increase in grain number. The response function for grain yield with CO 2 concentration strongly suggests a non-linear response, where yield stimulation levels off at ~600 ppm. This was supported by the meta-analysis, which did not indicate any significant difference in yield stimulation in wheat grown at 456–600 ppm compared to 601–750 ppm. Yield response to eCO 2 was independent of fumigation technique and rooting environment, but clearly related to site productivity, where relative CO 2 yield stimulation was stronger in low productive systems. The non-linear yield response, saturating at a relatively modest elevation of CO 2 , was of large importance for crop modelling and assessments of future food production under rising CO 2
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| 2. |
- Pleijel, Håkan, 1958, et al.
(author)
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Nitrogen application is required to realize wheat yield stimulation by elevated CO2 but will not remove the CO2 -induced reduction in grain protein concentration
- 2019
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In: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 25, s. 1868-1876
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Journal article (peer-reviewed)abstract
- © 2019 John Wiley & Sons Ltd Elevated CO 2 (eCO 2 ) generally promotes increased grain yield (GY) and decreased grain protein concentration (GPC), but the extent to which these effects depend on the magnitude of fertilization remains unclear. We collected data on the eCO 2 responses of GY, GPC and grain protein yield and their relationships with nitrogen (N) application rates across experimental data covering 11 field grown wheat (Triticum aestivum) cultivars studied in eight countries on four continents. The eCO 2 -induced stimulation of GY increased with N application rates up to ~200kg/ha. At higher N application, stimulation of GY by eCO 2 stagnated or even declined. This was valid both when the yield stimulation was expressed as the total effect and using per ppm CO 2 scaling. GPC was decreased by on average 7% under eCO 2 and the magnitude of this effect did not depend on N application rate. The net effect of responses on GY and protein concentration was that eCO 2 typically increased and decreased grain protein yield at N application rates below and above ~100kg/ha respectively. We conclude that a negative effect on wheat GPC seems inevitable under eCO 2 and that substantial N application rates may be required to sustain wheat protein yields in a world with rising CO 2 .
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| 3. |
- Pleijel, Håkan, 1958, et al.
(author)
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Ozone impact on wheat in Europe, Asia and North America – A comparison
- 2019
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 664, s. 908-914
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Journal article (peer-reviewed)abstract
- © 2019 Elsevier B.V. Data from experiments where field-grown wheat was exposed to ozone were collated in order to compare the effects in Europe, Asia and North America using dose-response regression. In addition to grain yield, average grain mass and harvest index were included to reflect the influence of ozone on the crop growth pattern. In order to include as many experiments as possible, daytime average ozone concentration was used as the ozone exposure index, but AOT40, estimated from average ozone concentrations, was also used to compare the performance of the two exposure metrics. The response to ozone differed significantly between the continents only for grain yield when using AOT40 as the exposure index. North American wheat was less sensitive than European and Asian that responded similarly. The variation in responses across all three continents was smallest for harvest index, followed by grain mass and grain yield. The highly consistent effect on harvest index shows that not only effects on biomass accumulation, but also on the partitioning of biomass, are important for the ozone-induced grain yield loss in wheat. The average duration of daily ozone exposure was longer in European experiments compared to North American and Asian. It cannot be excluded that this contributed to the indicated higher ozone sensitivity in European wheat in relation to North American. The main conclusions from this study are that on the average the response of wheat to ozone was lower for the older North American experiments and that the ozone response of the growth pattern reflected by grain mass and harvest index did not differ between continents.
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