| 1. |
- Ainsworth, Elizabeth A., et al.
(författare)
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Next generation of elevated [CO2] experiments with crops: a critical investment for feeding the future world
- 2008
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Ingår i: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 31:9, s. 1317-1324
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Tidskriftsartikel (refereegranskat)abstract
- A rising global population and demand for protein-rich diets are increasing pressure to maximize agricultural productivity. Rising atmospheric [CO2] is altering global temperature and precipitation patterns, which challenges agricultural productivity. While rising [CO2] provides a unique opportunity to increase the productivity of C-3 crops, average yield stimulation observed to date is well below potential gains. Thus, there is room for improving productivity. However, only a fraction of available germplasm of crops has been tested for CO2 responsiveness. Yield is a complex phenotypic trait determined by the interactions of a genotype with the environment. Selection of promising genotypes and characterization of response mechanisms will only be effective if crop improvement and systems biology approaches are closely linked to production environments, that is, on the farm within major growing regions. Free air CO2 enrichment (FACE) experiments can provide the platform upon which to conduct genetic screening and elucidate the inheritance and mechanisms that underlie genotypic differences in productivity under elevated [CO2]. We propose a new generation of large-scale, low-cost per unit area FACE experiments to identify the most CO2-responsive genotypes and provide starting lines for future breeding programmes. This is necessary if we are to realize the potential for yield gains in the future.
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| 2. |
- Manderscheid, Remy, et al.
(författare)
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Glufosinate treatment of weeds results in ammonia emission by plants
- 2005
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Ingår i: Agriculture, Ecosystems & Environment. - Amsterdam : Elsevier. - 0167-8809 .- 1873-2305. ; 109:1-2, s. 129-140
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Tidskriftsartikel (refereegranskat)abstract
- The herbicide glufosinate, which is also called phosphinothricin (PPT), is known to inhibit glutamine synthetase and thus causes a blockage of ammonium (re)assimilation in plants. The objective of the present study was to test whether application of this herbicide results in an ammonia volatilization from the plants and to quantify nitrogen loss via ammonia emission. Four different weed species (Chenopodium album, Echinocloa crus-galli, Solanum nigrum, Tripleurospermum inodorum) were grown as monocultures in the greenhouse and treated with PPT when their canopies covered the soil. In the first experiment, whole shoot samples were taken during the following days and analysed for ammonium, pH and total nitrogen content. In the second experiment, apoplastic pH and ammonium concentration of the leaves were measured after herbicide application and used for the calculation of Γ-values (ratio between NH4+ and H+ concentration), the stomatal NH3 compensation point and the canopy net NH3 flux with a soil vegetation atmosphere transport (SVAT) model.Herbicide treatment caused a rapid increase in shoot ammonium concentration and the ammonium portion of the plant total nitrogen ranged from 0.6 to 0.9% and from 17 to 44% before and after PPT application, respectively. S. nigrum showed a strong increase in ammonium portion (35%) followed by a decrease (20%), which may have resulted from ammonia volatilization. The difference in total shoot nitrogen content per ground area at the start and 2 weeks after PPT application averaged for the three C3 weed species to a nitrogen loss of ca. 0.4 g N m−2 or approximately 13% of the total nitrogen in the weed canopy. Analysis of the apoplastic fluid yielded an increase in ammonium concentration and a pH decrease after an initial increase on day 1 after the PPT treatment. In order to evaluate the potential for ammonia loss, the Γ-value was calculated for both apoplastic and tissue water. S. nigrum showed the most dramatic increases in both apoplastic and tissue–water Γ-values 4 days after PPT treatment. The calculated stomatal NH3 compensation point was strongly elevated after PPT treatment. However, temporal changes of apoplastic pH and ammonium concentration varied between the species and the modelled ammonia emission ranged from 0.03 to 0.09 g N m−2. It is concluded that PPT application results in an ammonia emission of ca.
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