Evaluation of the acetylene inhibition method for measuring denitrification in soilless plant culture systems

1997 ◽  
Vol 24 (1) ◽  
pp. 111-117 ◽  
Author(s):  
D. Daum ◽  
M. K. Schenk
Keyword(s):  
Acetylene Inhibition ◽  
Culture Systems ◽  
Plant Culture ◽  
Acetylene Inhibition Method

scholarly journals Growth and Photomorphogenesis of Pepper Plants under Red Light-emitting Diodes with Supplemental Blue or Far-red Lighting

1995 ◽  
Vol 120 (5) ◽  
pp. 808-813 ◽  
Author(s):  
Christopher S. Brown ◽  
Andrew C. Schuerger ◽  
John C. Sager
Keyword(s):  
Infrared Radiation ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Plant Biomass ◽  
Dry Matter Partitioning ◽  
Light Emitting ◽  
Culture Systems ◽  
Plant Culture ◽  
Red Leds ◽  
Red Radiation

Light-emitting diodes (LEDs) are a potential irradiation source for intensive plant culture systems and photobiological research. They have small size, low mass, a long functional life, and narrow spectral output. In this study, we measured the growth and dry matter partitioning of `Hungarian Wax' pepper (Capsicum annum L.) plants grown under red LEDs compared with similar plants grown under red LEDs with supplemental blue or far-red radiation or under broad spectrum metal halide (MH) lamps. Additionally, we describe the thermal and spectra1 characteristics of these sources. The LEDs used in this study had a narrow bandwidth at half peak height (25 nm) and a focused maximum spectral output at 660 nm for the red and 735 nm for the far-red. Near infrared radiation (800 to 3000 nm) was below detection and thermal infrared radiation (3000 to 50,000 nm) was lower in the LEDs compared to the MH source. Although the red to far-red ratio varied considerably, the calculated phytochrome photostationary state (φ) was only slightly different between the radiation sources. Plant biomass was reduced when peppers were grown under red LEDs in the absence of blue wavelengths compared to plants grown under supplemental blue fluorescent lamps or MH lamps. The addition of far-red radiation resulted in taller plants with greater stem mass than red LEDs alone. There were fewer leaves under red or red plus far-red radiation than with lamps producing blue wavelengths. These results indicate that red LEDs may be suitable, in proper combination with other wavelengths of light, for the culture of plants in tightly controlled environments such as space-based plant culture systems.

Denitrification and dissimilatory nitrate reduction to ammonium in digested sludge

1981 ◽  
Vol 27 (9) ◽  
pp. 878-885 ◽  
Author(s):  
Heinrich F. Kaspar ◽  
James M. Tiedje ◽  
Richard B. Firestone
Keyword(s):  
Enrichment Culture ◽  
Anaerobic Sludge ◽  
Solid Carbon ◽  
Acetylene Inhibition ◽  
Digested Sludge ◽  
Carbon And Nitrogen ◽  
Oxide Substrates ◽  
Anaerobic Energy ◽  
Nitrate Concentrations ◽  
Acetylene Inhibition Method

Acetylene inhibition and 13N methods were used to assay digested sludge for its potential to denitrify and to reduce nitrate to ammonium. At nitrate concentrations below 10 μM, the reduction of N2O to N2 was not inhibited by acetylene concentrations as high as 80 kPa, though at higher nitrate concentrations acetylene was an effective inhibitor. NO, N2O, and N2 were produces immediately after addition of nitrate or nitrite, indicating that denitrifying enzymes were present. NO was maintained at a concentration of 2–5 nM, while nitrate or nitrite were being reduced, but this gas was depleted once the ionic N oxide substrates were exhausted. Acetylene had little effect on appearance and disappearance of NO. It was also noted that NO was readily consumed by chemical reactions in the anaerobic sludge. Added N2O was reduced without a lag, but pasteurized samples did not consume N2O although they produced it. Fresh digested sludge reduced 60–70% of the added 13NO3− to 13NH4+ with the rest of the NO3−-N presumably lost to denitrification. This agrees well with the nitrate partitioning observed by the acetylene inhibition method in which 30–40% of the NO3−-N was recovered as N2O. Denitrification capacity persisted in both digested sludge and methanogenic enrichment culture which had been grown in a chemostat for 2.5 years with acetate and ammonium as the solid carbon and nitrogen source. This suggests that denitrifiers with capacities for alternative anaerobic energy metabolism may be more common than now known.

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