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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

Relationship between whole plant mass measured at the end of phase I and total amount of labelled nitrogen and carbon assimilated by leaves during phase II.The line shows a significant (P < 0.05) negative relationship between total biomass accumulation and foliar uptake of NH3, which was independent of foliar area and plant nitrogen content (Supp Fig 1). This relationship was not significant for assimilation of a pulse of CO2 (R2 = 0.74), which mainly responded to changes in stomatal conductance produced by a history of ambient or elevated CO2. Error bars represent standard errors of the mean.
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f4: Relationship between whole plant mass measured at the end of phase I and total amount of labelled nitrogen and carbon assimilated by leaves during phase II.The line shows a significant (P < 0.05) negative relationship between total biomass accumulation and foliar uptake of NH3, which was independent of foliar area and plant nitrogen content (Supp Fig 1). This relationship was not significant for assimilation of a pulse of CO2 (R2 = 0.74), which mainly responded to changes in stomatal conductance produced by a history of ambient or elevated CO2. Error bars represent standard errors of the mean.

Mentions: Our results represent an integrated measure of declines in foliar gas exchange induced by elevated CO2, and the additional influence of soil nitrogen form, on NH3 assimilation, an effect inversely correlated with plant size (Fig. 4). Notably, this effect was independent of foliar area and plant nitrogen content (Supp Fig 3). Furthermore, uptake of a pulse of 13CO2 was not significantly correlated with any allometric parameter, instead reflecting solely a decline in stomatal conductance (~23% on average) in plants subjected to CO2 enrichment (Supp Table 3). This result is consistent with earlier experiments performed using the same species under stress-free conditions (i.e. irrigated twice daily)3640, and is comparable to CO2-induced declines in stomatal conductance recorded in a variety of other species and experimental settings24142.


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)

Relationship between whole plant mass measured at the end of phase I and total amount of labelled nitrogen and carbon assimilated by leaves during phase II.The line shows a significant (P < 0.05) negative relationship between total biomass accumulation and foliar uptake of NH3, which was independent of foliar area and plant nitrogen content (Supp Fig 1). This relationship was not significant for assimilation of a pulse of CO2 (R2 = 0.74), which mainly responded to changes in stomatal conductance produced by a history of ambient or elevated CO2. Error bars represent standard errors of the mean.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Relationship between whole plant mass measured at the end of phase I and total amount of labelled nitrogen and carbon assimilated by leaves during phase II.The line shows a significant (P < 0.05) negative relationship between total biomass accumulation and foliar uptake of NH3, which was independent of foliar area and plant nitrogen content (Supp Fig 1). This relationship was not significant for assimilation of a pulse of CO2 (R2 = 0.74), which mainly responded to changes in stomatal conductance produced by a history of ambient or elevated CO2. Error bars represent standard errors of the mean.
Mentions: Our results represent an integrated measure of declines in foliar gas exchange induced by elevated CO2, and the additional influence of soil nitrogen form, on NH3 assimilation, an effect inversely correlated with plant size (Fig. 4). Notably, this effect was independent of foliar area and plant nitrogen content (Supp Fig 3). Furthermore, uptake of a pulse of 13CO2 was not significantly correlated with any allometric parameter, instead reflecting solely a decline in stomatal conductance (~23% on average) in plants subjected to CO2 enrichment (Supp Table 3). This result is consistent with earlier experiments performed using the same species under stress-free conditions (i.e. irrigated twice daily)3640, and is comparable to CO2-induced declines in stomatal conductance recorded in a variety of other species and experimental settings24142.

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