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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.


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Concentration of internal oxygen in P. australis culm stumps after experimental removal of the culms above the implanted oxygen sensor. The pith cavity of the remaining stump was sealed airtight and measurements continued for 20 h overnight. Exponential curves were fitted with time (t in [s]) against the oxygen courses with the equation (1): ; compare to Figure 3. (A) plant A1; (B) plant A2. The coefficients of determination were in all fits above r2 > 0.9 with P < 0.001.
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plw025-F4: Concentration of internal oxygen in P. australis culm stumps after experimental removal of the culms above the implanted oxygen sensor. The pith cavity of the remaining stump was sealed airtight and measurements continued for 20 h overnight. Exponential curves were fitted with time (t in [s]) against the oxygen courses with the equation (1): ; compare to Figure 3. (A) plant A1; (B) plant A2. The coefficients of determination were in all fits above r2 > 0.9 with P < 0.001.

Mentions: The analyzed culms A1 and A2 were cut at the internodes above the oxygen sensor insertion on 27 August 2009 at 12:15 h and the stumps were given an airtight seal. The [O2] in both culms and rhizomes showed a sudden and steep decrease after cutting (Fig. 4). Clearly, internal [O2] decreased despite high PFD and low RH. The initiated effect was similar to, but faster than, the evening decreases observed previously. Initial slopes were −8.4 % h−1 in culm A1 and −1.5 % h−1 in culm A2, and from −6.3 to −8.4 % h−1 in the respective rhizomes. In plant A2, [O2] dropped to values in the range of overnight levels 18 h after the culm was cut (culm stump: ∼16.7 %, rhizome: ∼8.4 %). About 12 h after the culm was cut, [O2] levels in culm stump and rhizome of plant A1 were also similar to overnight decline. However, during the following 6 h, the internal [O2] decreased further to about 7.3 and 5.2 % in culm stump and rhizome, respectively. Thus, the previously observed mechanisms for down-regulation of oxygen consumption were also initiated when oxygen supply was experimentally interrupted but these mechanisms were not sufficient beyond 12 h without new, actively ventilated air.Figure 4.


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
Concentration of internal oxygen in P. australis culm stumps after experimental removal of the culms above the implanted oxygen sensor. The pith cavity of the remaining stump was sealed airtight and measurements continued for 20 h overnight. Exponential curves were fitted with time (t in [s]) against the oxygen courses with the equation (1): ; compare to Figure 3. (A) plant A1; (B) plant A2. The coefficients of determination were in all fits above r2 > 0.9 with P < 0.001.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940480&req=5

plw025-F4: Concentration of internal oxygen in P. australis culm stumps after experimental removal of the culms above the implanted oxygen sensor. The pith cavity of the remaining stump was sealed airtight and measurements continued for 20 h overnight. Exponential curves were fitted with time (t in [s]) against the oxygen courses with the equation (1): ; compare to Figure 3. (A) plant A1; (B) plant A2. The coefficients of determination were in all fits above r2 > 0.9 with P < 0.001.
Mentions: The analyzed culms A1 and A2 were cut at the internodes above the oxygen sensor insertion on 27 August 2009 at 12:15 h and the stumps were given an airtight seal. The [O2] in both culms and rhizomes showed a sudden and steep decrease after cutting (Fig. 4). Clearly, internal [O2] decreased despite high PFD and low RH. The initiated effect was similar to, but faster than, the evening decreases observed previously. Initial slopes were −8.4 % h−1 in culm A1 and −1.5 % h−1 in culm A2, and from −6.3 to −8.4 % h−1 in the respective rhizomes. In plant A2, [O2] dropped to values in the range of overnight levels 18 h after the culm was cut (culm stump: ∼16.7 %, rhizome: ∼8.4 %). About 12 h after the culm was cut, [O2] levels in culm stump and rhizome of plant A1 were also similar to overnight decline. However, during the following 6 h, the internal [O2] decreased further to about 7.3 and 5.2 % in culm stump and rhizome, respectively. Thus, the previously observed mechanisms for down-regulation of oxygen consumption were also initiated when oxygen supply was experimentally interrupted but these mechanisms were not sufficient beyond 12 h without new, actively ventilated air.Figure 4.

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.


Related in: MedlinePlus