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Carbon dioxide level and form of soil nitrogen regulate assimilation of atmospheric ammonia in young trees.

Silva LC, Salamanca-Jimenez A, Doane TA, Horwath WR - Sci Rep (2015)

Bottom Line: Using Coffea arabica as a model tree species, we observed an additive effect on growth, by which aboveground productivity was highest under elevated CO2 and ammonium fertilization, while nitrate fertilization favored greater belowground biomass allocation regardless of CO2 concentration.Surprisingly, trees with the largest aboveground biomass assimilated significantly less NH3 than the smaller trees.Nitrogen form is therefore an intrinsic component of physiological responses to atmospheric change, including assimilation of gaseous nitrogen as influenced by plant growth history.

View Article: PubMed Central - PubMed

Affiliation: Department of Land Air and Water Resources. University of California, Davis, CA-95616.

ABSTRACT
The influence of carbon dioxide (CO2) and soil fertility on the physiological performance of plants has been extensively studied, but their combined effect is notoriously difficult to predict. Using Coffea arabica as a model tree species, we observed an additive effect on growth, by which aboveground productivity was highest under elevated CO2 and ammonium fertilization, while nitrate fertilization favored greater belowground biomass allocation regardless of CO2 concentration. A pulse of labelled gases ((13)CO2 and (15)NH3) was administered to these trees as a means to determine the legacy effect of CO2 level and soil nitrogen form on foliar gas uptake and translocation. Surprisingly, trees with the largest aboveground biomass assimilated significantly less NH3 than the smaller trees. This was partly explained by declines in stomatal conductance in plants grown under elevated CO2. However, unlike the (13)CO2 pulse, assimilation and transport of the (15)NH3 pulse to shoots and roots varied as a function of interactions between stomatal conductance and direct plant response to the form of soil nitrogen, observed as differences in tissue nitrogen content and biomass allocation. Nitrogen form is therefore an intrinsic component of physiological responses to atmospheric change, including assimilation of gaseous nitrogen as influenced by plant growth history.

No MeSH data available.


Related in: MedlinePlus

Isotopic data (phase II) reported as mass of carbon and nitrogen derived from 13CO2 and 15NH3 assimilated by leaves and present in plant compartments at one hour and five days after exposure to labelled gases.Horizontal lines within the boxes represent median values. The ends of the box represent the 75th and 25th quantiles. Treatments applied during phase I significantly affected uptake and allocation of the pulse of labelled C and N. These treatments are: Ambient CO2 (A, 400 ppm); Elevated CO2 (E, 700 ppm); soil nitrogen supplied as NH4+ or as NO3−. A full factorial analysis of main effects and interactions is presented in Supp Table 2. Letters show significant differences determined using Tukey HSD tests across treatments within each plant compartment (P < 0.05). Where no letters are shown differences were not significant.
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f3: Isotopic data (phase II) reported as mass of carbon and nitrogen derived from 13CO2 and 15NH3 assimilated by leaves and present in plant compartments at one hour and five days after exposure to labelled gases.Horizontal lines within the boxes represent median values. The ends of the box represent the 75th and 25th quantiles. Treatments applied during phase I significantly affected uptake and allocation of the pulse of labelled C and N. These treatments are: Ambient CO2 (A, 400 ppm); Elevated CO2 (E, 700 ppm); soil nitrogen supplied as NH4+ or as NO3−. A full factorial analysis of main effects and interactions is presented in Supp Table 2. Letters show significant differences determined using Tukey HSD tests across treatments within each plant compartment (P < 0.05). Where no letters are shown differences were not significant.

Mentions: After 150 days, we assessed the legacy effect of growth conditions (i.e. atmospheric CO2 level and form of soil nitrogen) on leaf carbon and nitrogen uptake and subsequent allocation. Plants from each treatment were labelled with a simultaneous pulse of isotopically enriched gases (13CO2 and 15NH3). After one hour of exposure, analysis of leaf, stem, and root tissue revealed that plants grown under a history of elevated CO2 assimilated significantly less 13CO2 and 15NH3 than those grown under a history of ambient CO2 (Fig. 3; Supp Table 2). Uptake of 15NH3 depended on the form of soil nitrogen, with highest uptake observed in the A-NO3− treatment. Carbon assimilation, on the other hand, was only affected by the CO2 treatment under which the plants had been previously grown. Surprisingly, plants grown under a history of elevated CO2 and NH4+, while larger, absorbed less of both labelled gases than smaller plants grown under ambient CO2 and NO3− (Fig. 3).


Carbon dioxide level and form of soil nitrogen regulate assimilation of atmospheric ammonia in young trees.

Silva LC, Salamanca-Jimenez A, Doane TA, Horwath WR - Sci Rep (2015)

Isotopic data (phase II) reported as mass of carbon and nitrogen derived from 13CO2 and 15NH3 assimilated by leaves and present in plant compartments at one hour and five days after exposure to labelled gases.Horizontal lines within the boxes represent median values. The ends of the box represent the 75th and 25th quantiles. Treatments applied during phase I significantly affected uptake and allocation of the pulse of labelled C and N. These treatments are: Ambient CO2 (A, 400 ppm); Elevated CO2 (E, 700 ppm); soil nitrogen supplied as NH4+ or as NO3−. A full factorial analysis of main effects and interactions is presented in Supp Table 2. Letters show significant differences determined using Tukey HSD tests across treatments within each plant compartment (P < 0.05). Where no letters are shown differences were not significant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543970&req=5

f3: Isotopic data (phase II) reported as mass of carbon and nitrogen derived from 13CO2 and 15NH3 assimilated by leaves and present in plant compartments at one hour and five days after exposure to labelled gases.Horizontal lines within the boxes represent median values. The ends of the box represent the 75th and 25th quantiles. Treatments applied during phase I significantly affected uptake and allocation of the pulse of labelled C and N. These treatments are: Ambient CO2 (A, 400 ppm); Elevated CO2 (E, 700 ppm); soil nitrogen supplied as NH4+ or as NO3−. A full factorial analysis of main effects and interactions is presented in Supp Table 2. Letters show significant differences determined using Tukey HSD tests across treatments within each plant compartment (P < 0.05). Where no letters are shown differences were not significant.
Mentions: After 150 days, we assessed the legacy effect of growth conditions (i.e. atmospheric CO2 level and form of soil nitrogen) on leaf carbon and nitrogen uptake and subsequent allocation. Plants from each treatment were labelled with a simultaneous pulse of isotopically enriched gases (13CO2 and 15NH3). After one hour of exposure, analysis of leaf, stem, and root tissue revealed that plants grown under a history of elevated CO2 assimilated significantly less 13CO2 and 15NH3 than those grown under a history of ambient CO2 (Fig. 3; Supp Table 2). Uptake of 15NH3 depended on the form of soil nitrogen, with highest uptake observed in the A-NO3− treatment. Carbon assimilation, on the other hand, was only affected by the CO2 treatment under which the plants had been previously grown. Surprisingly, plants grown under a history of elevated CO2 and NH4+, while larger, absorbed less of both labelled gases than smaller plants grown under ambient CO2 and NO3− (Fig. 3).

Bottom Line: Using Coffea arabica as a model tree species, we observed an additive effect on growth, by which aboveground productivity was highest under elevated CO2 and ammonium fertilization, while nitrate fertilization favored greater belowground biomass allocation regardless of CO2 concentration.Surprisingly, trees with the largest aboveground biomass assimilated significantly less NH3 than the smaller trees.Nitrogen form is therefore an intrinsic component of physiological responses to atmospheric change, including assimilation of gaseous nitrogen as influenced by plant growth history.

View Article: PubMed Central - PubMed

Affiliation: Department of Land Air and Water Resources. University of California, Davis, CA-95616.

ABSTRACT
The influence of carbon dioxide (CO2) and soil fertility on the physiological performance of plants has been extensively studied, but their combined effect is notoriously difficult to predict. Using Coffea arabica as a model tree species, we observed an additive effect on growth, by which aboveground productivity was highest under elevated CO2 and ammonium fertilization, while nitrate fertilization favored greater belowground biomass allocation regardless of CO2 concentration. A pulse of labelled gases ((13)CO2 and (15)NH3) was administered to these trees as a means to determine the legacy effect of CO2 level and soil nitrogen form on foliar gas uptake and translocation. Surprisingly, trees with the largest aboveground biomass assimilated significantly less NH3 than the smaller trees. This was partly explained by declines in stomatal conductance in plants grown under elevated CO2. However, unlike the (13)CO2 pulse, assimilation and transport of the (15)NH3 pulse to shoots and roots varied as a function of interactions between stomatal conductance and direct plant response to the form of soil nitrogen, observed as differences in tissue nitrogen content and biomass allocation. Nitrogen form is therefore an intrinsic component of physiological responses to atmospheric change, including assimilation of gaseous nitrogen as influenced by plant growth history.

No MeSH data available.


Related in: MedlinePlus