Search results for "respiration."
showing 10 items of 533 documents
Use of gaseous 13NH3 administered to intact leaves of Nicotiana tabacum to study changes in nitrogen utilization during defence induction
2010
Nitrogen-13 (t(1/2) 9.97 m), a radioactive isotope of nitrogen, offers unique opportunities to explore plant nitrogen utilization over short time periods. Here we describe a method for administering (13)N as gaseous (13)NH(3) to intact leaves of Nicotiana tabacum L. (cv Samsun), and measuring the labelled amino acids using radio high-performance liquid chromatography (HPLC) on tissue extract. We used this method to study the effects of defence induction on plant nitrogen utilization by applying treatments of methyl jasmonate (MeJA), a potent defence elicitor. MeJA caused a significant increase relative to controls in key [(13)N]amino acids, including serine, glycine and alanine by 4 h post-…
Effects of Pentachlorophenol and Biotic Interactions on Soil Fauna and Decomposition in Humus Soil
1995
In a laboratory experiment, effects of chemical stress (pentachlorophenol, PCP, at concentrations of 0, 50, and 500 mg/kg) and biotic interactions (nematodes in the presence or absence of collembolas and enchytraeids) on the community structure of soil animals and decomposition processes were studied. PCP was strongly adsorbed to humus that contained 65% organic matter. Numbers of fungal-feeding nematodes decreased significantly at the highest PCP concentration, while no effects were found in bacterial feeders. There were differences in the numbers of nematodes between different animal combinations, but at the highest PCP concentration, collembolas and enchytraeids had no effect on them. Nu…
Effect of Glufosinate (Phosphinothricin) and Inhibitors of Photorespiration on Photosynthesis and Ribulose-1,5-Bisphosphate Carboxylase Activity
1992
Summary Glufosinate (phosphinothricin) irreversibly inhibits glutamine synthetase and leads to a great decrease in the amino acids glutamine, glutamate, aspartate, serine, glycine and alanine. Due to the lack of glutamate and serine, the transamination of glyoxylate into glycine in the course of photorespiration cannot take place. The inhibition of this part of the photorespiratory process plays the essential role with respect to the photosynthesis inhibition caused by PPT under atmospheric conditions. After addition of different photorespiration or Calvin cycle intermediates to phosphinothricin no decrease in photosynthesis inhibition can be measured. This suggests that photosynthesis inhi…
Changes in soil microbial activity and physicochemical properties in agricultural soils in Eastern Spain
2015
Agricultural land management greatly affects soil properties. Microbial soil communities are the most sensitive and rapid indicators of perturbations in land use and soil enzyme activities are sensitive biological indicators of the effects of soil management practices. Citrus orchards frequently have degraded soils and this paper evaluates how land management in citrus orchards can improve soil quality. A field experiment was performed in an orchard of orange trees (<em>Citrus Sinensis</em>) in the Alcoleja Experimental Station (Eastern Spain) with clay-loam agricultural soils to assess the long-term effects of herbicides with inorganic fertilizers (H), intensive ploughing and i…
The Effect of Bialaphos on Ammonium-Assimilation and Photosynthesis II. Effect on Photosynthesis and Photorespiration
1989
Abstract The application of bialaphos (phosphinothricyl-alanyl-alanine) effects a quick photosynthesis inhibition under atmospheric conditions (400 ppm CO2, 21% O2). However, under conditions (1000 ppm CO2, 2% O2) under which photorespiration cannot occur there is no photosynthesis inhibition. In the previous investigation it could be shown that bialaphos splits in plants into phosphinothricin and alanine. The inhibition of glutamine synthetase through freed phosphinothricin results in an NH4 +-accumulation and a decrease in glutamine. With the addition of glutamine, photosynthesis inhibition by bialaphos can be reduced. An NH4 +-accumulation takes place under atmospheric conditions as well…
The Interaction of State Transitions and Chlororespiration in the Xanthophycean Alga Pleurochloris Meiringensis
1990
Wavelength dependent State I-State II-transitions have been shown to exist in chlorophytes and red algae. Little is known about the regulation of energy distribution between the photosystems of chlorophyll c-containing plants. Previously it was shown that in the xanthophycean alga Pleurochloris meiringensis two states of energy distribution could be established [l]: In state “D” light is preferentially transferred to PS II, whereas in state “L” PS I is favoured. These state regulations strictly depend on the intensity and not on the wavelength of prei1lumination. In this paper we give new evidence that chlororespiration is involved in the mechanism of state “L”-state “D”-transitions.
Cuantificación de la calidad embrionaria mediante el consumo de oxígeno durante el proceso rutinario de incubación y desarrollo in vitro
2015
A pesar de la aplicación intensiva de las TRA y de las cada vez mayores tasas de éxito, hay ciertos aspectos de estos tratamientos que continúan sin resolverse, siendo una limitación importante el hecho de que sólo entre el 10-20% de los embriones transferidos al útero sean capaces de dar lugar a un embarazo a término. Esta limitación está promoviendo el desarrollo de nuevas técnicas no invasivas para seleccionar embriones más eficazmente que mediante el mero criterio morfológico. Las evidencias apoyadas por distintos trabajos encontrados en la literatura hacen que consideremos algunos métodos no invasivos, como la actividad metabólica de ovocitos y embriones, como buenos predictores de la …
Biological Stability of Organic Fraction of Municipal Solid Wastes During Composting Processes
2018
The article shows results of monitoring of a Sicilian composting plant (southern Italy). In particular, the biological stability of the organic fraction of municipal solid wastes has been monitored. Two experimental periods have been carried out: (1) plant start-up and (2) first operation period. The biological stability has been evaluated throughout the dynamic respiration index (DRI). This index was determined at different stages of process, for each phase. To our knowledge, no work has been previously published on the monitoring of composting plants in southern Italy. This work has the originality of using the DRI measured data for improving operation of a full-scale composting plant, ra…
Co-treatment of landfill leachate in laboratory-scale sequencing batch reactors: analysis of system performance and biomass activity by means of resp…
2014
Aged or mature leachate, produced by old landfills, can be very refractory; for this reason mature leachate is difficult to treat alone, but it can be co-treated with sewage or domestic wastewater. The aim of the study was to investigate the feasibility of leachate co-treatment with synthetic wastewater, in terms of process performance and biomass activity, by means of respirometric techniques. Two sequencing batch reactors (SBRs), named SBR1 and SBR2, were fed with synthetic wastewater and two different percentages of landfill leachate (respectively 10% and 50% v v−1 in SBR1 and SBR2). The results showed good chemical oxygen demand (COD) removal efficiency for both reactors, with average C…
Effects of earthworms on decomposition and metal availability in contaminated soil: Microcosm studies of populations with different exposure histories
2006
Abstract Population-specific differences in the responses of earthworms to simultaneous exposure to Cu and Zn were studied in microcosm experiments. Two populations of Aporrectodea caliginosa tuberculata (Eisen) with different metal exposure histories were chosen for the studies. Microcosms were prepared containing either uncontaminated soil or soils with low or high combined Cu/Zn -concentrations (79/139 or 178/311 mg kg −1 dry mass of soil, respectively). Earthworms from each population were introduced to the microcosm treatments with some microcosms serving as controls without earthworms. One series of microcosms was destructively sampled after 16 weeks incubation in a climate chamber. S…