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Diurnal dynamics of oxygen and carbon dioxide concentrations in shoots and rhizomes of a perennial in a constructed wetland indicate down-regulation of below ground oxygen consumption

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ABSTRACT

Plants have evolved mechanisms to provide oxygen to their parts in oxygen-free environments like wetland sediments. We measured the diurnal courses of oxygen supply to rhizomes of the common reed, a widespread wetland plant. During the day the below-ground plant parts can rely on ample oxygen, but during the night its supply to rhizomes and roots as well as to the whole assembly of associated microorganisms is limited. The key finding of the study was that during periods of low oxygen supply the whole below-ground biota reduces its respiration. This regulation mechanism helps the biota survive unfavourable periods.

No MeSH data available.


Oxygen concentration recorded overnight from 17:00 h until 5:00 h in culms and rhizomes of P. australis plant A1 (A–C) and plant A2 (D–F). Exponential curves were fitted with time (t in [s]) against the oxygen courses with the equation (1): . The coefficients of determination were in all fits above r2 > 0.9 with P < 0.001, except in (E) culm A2 from 25 to 26 August 2009 (r2 = 0.76, P < 0.001).
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plw025-F3: Oxygen concentration recorded overnight from 17:00 h until 5:00 h in culms and rhizomes of P. australis plant A1 (A–C) and plant A2 (D–F). Exponential curves were fitted with time (t in [s]) against the oxygen courses with the equation (1): . The coefficients of determination were in all fits above r2 > 0.9 with P < 0.001, except in (E) culm A2 from 25 to 26 August 2009 (r2 = 0.76, P < 0.001).

Mentions: The coefficients of determination (r2) for the exponential Equation (1) modelling the nocturnal courses of [O2] in culms and rhizomes were above 0.9 (Fig. 3), except in culm A2 from 25 to 26 August 2009 (r2 = 0.76). The fitted intercept (c) was interpreted as the minimum level of internal [O2] convergence due to the balance between oxygen demand by aerobic respiration of plant tissues, metabolic activity in the sediment, radial oxygen loss, and oxygen supply through the aerenchyma under the non-through-flow condition. Thus [O2] approached a night-time steady-state oxygen level of about 10.7–12.7 % in culm A1, and 15.5–15.7 % in culm A2. In both plants, rhizome-[O2] converged to values around 6.7–9.0 %.Figure 3.


Diurnal dynamics of oxygen and carbon dioxide concentrations in shoots and rhizomes of a perennial in a constructed wetland indicate down-regulation of below ground oxygen consumption
Oxygen concentration recorded overnight from 17:00 h until 5:00 h in culms and rhizomes of P. australis plant A1 (A–C) and plant A2 (D–F). Exponential curves were fitted with time (t in [s]) against the oxygen courses with the equation (1): . The coefficients of determination were in all fits above r2 > 0.9 with P < 0.001, except in (E) culm A2 from 25 to 26 August 2009 (r2 = 0.76, P < 0.001).
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Related In: Results  -  Collection

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plw025-F3: Oxygen concentration recorded overnight from 17:00 h until 5:00 h in culms and rhizomes of P. australis plant A1 (A–C) and plant A2 (D–F). Exponential curves were fitted with time (t in [s]) against the oxygen courses with the equation (1): . The coefficients of determination were in all fits above r2 > 0.9 with P < 0.001, except in (E) culm A2 from 25 to 26 August 2009 (r2 = 0.76, P < 0.001).
Mentions: The coefficients of determination (r2) for the exponential Equation (1) modelling the nocturnal courses of [O2] in culms and rhizomes were above 0.9 (Fig. 3), except in culm A2 from 25 to 26 August 2009 (r2 = 0.76). The fitted intercept (c) was interpreted as the minimum level of internal [O2] convergence due to the balance between oxygen demand by aerobic respiration of plant tissues, metabolic activity in the sediment, radial oxygen loss, and oxygen supply through the aerenchyma under the non-through-flow condition. Thus [O2] approached a night-time steady-state oxygen level of about 10.7–12.7 % in culm A1, and 15.5–15.7 % in culm A2. In both plants, rhizome-[O2] converged to values around 6.7–9.0 %.Figure 3.

View Article: PubMed Central - PubMed

ABSTRACT

Plants have evolved mechanisms to provide oxygen to their parts in oxygen-free environments like wetland sediments. We measured the diurnal courses of oxygen supply to rhizomes of the common reed, a widespread wetland plant. During the day the below-ground plant parts can rely on ample oxygen, but during the night its supply to rhizomes and roots as well as to the whole assembly of associated microorganisms is limited. The key finding of the study was that during periods of low oxygen supply the whole below-ground biota reduces its respiration. This regulation mechanism helps the biota survive unfavourable periods.

No MeSH data available.