chlorophyll-a and ethylene-diurea

The present study evaluated the impact of high ambient O

Topics: Air Pollutants; Animals; Antioxidants; Biomass; Chlorophyll; Lipid Peroxidation; Oxidation-Reduction; Ozone; Phenylurea Compounds; Plant Leaves; Proteome; Proteomics; Seasons; Triticum

Wheat is a major staple food and its sensitivity to the gas pollutant ozone (O

Topics: Antioxidants; Ascorbic Acid; Beijing; China; Chlorophyll; Malondialdehyde; Ozone; Phenylurea Compounds; Photosynthesis; Plant Stomata; Seasons; Triticum

The antiozonant and research tool ethylene diurea (EDU) is widely studied as a phytoprotectant against the widespread pollutant ground-surface ozone. Although it has been extensively used, its potential toxicity in the absence of ozone is unknown and its mode of action is unclear. The purpose of this research was to toxicologically assess EDU and to further investigate its mode of action using Lemna minor L. as a model organism. Application of EDU concentrations greater than 593 mg L(-1) (practically 600 mg L(-1)) resulted in adverse inhibition of colony growth. As no-observed-toxic-effects concentration (NOEL) we recommend a concentration of 296 mg L(-1) (practically 300 mg L(-1)). A hormetic response was detected, i.e. stimulatory effects of low EDU concentrations, which may indicate overcompensation in response to disruption in homeostasis. Growth inhibition and suppressed biomass were associated with impacted chlorophyll a fluorescence (ΦPSII, qP and ETR). Furthermore, EDU increased mesophyll thickness, as indicated by frond succulence index. Applications of concentrations ≥593 mg L(-1) to uncontrolled environments should be avoided due to potential toxicity to sensitive organisms and the environment.

Topics: Air Pollutants; Araceae; Biological Assay; Biomass; Chlorophyll; Chlorophyll A; Homeostasis; Hormesis; Models, Biological; Ozone; Phenylurea Compounds; Plant Leaves

The long-term and diurnal responses of photosystem II (PSII) performance to near-ambient UV-B radiation were investigated in High Arctic Betula nana. We conducted an UV exclusion experiment with five replicated blocks consisting of open control (no filter), photosynthetic active radiation and UV-B transparent filter control (Teflon), UV-B-absorbing filter (Mylar) and UV-AB-absorbing filter (Lexan). Ethylenediurea (EDU), a chemical normally used to protect plants against ozone injury, was sprayed on the leaves both in the field and in an additional laboratory study to investigate if EDU mitigated the effects of UV-B. Chlorophyll-a fluorescence induction curves were used for analysis of OJIP test parameters. Near-ambient UV-B radiation reduced across season maximum quantum yield (TR(o) /ABS = F(v) /F(m)), approximated number of active PSII reaction center (RC/ABS) and the performance index (PI(ABS)), despite improved leaf screening against UV-B with higher content of UV-B-absorbing compounds and a lower specific leaf area. EDU application counteracted the negative impact of UV-B on TR(o) /ABS, RC/ABS and PI(ABS) . This indicates that the mechanisms behind UV-B and ozone damage share some common features. The midday depression was present in all treatments, but TR(o) /ABS and PI(ABS) were persistently lower in near-ambient UV-B compared to UV-B reduction. The recovery phase was particularly impaired in near-ambient UV-B and interactive effects between treatment × hour raised TR(o) /ABS, RC/ABS and PI(ABS) higher in reduced UV-B compared to near-ambient UV-B. This demonstrates current solar UV-B to reduce the PSII performance both on a daily as well as a seasonal basis in this High Arctic species.

Topics: Arctic Regions; Betula; Chlorophyll; Chlorophyll A; Circadian Rhythm; Electron Transport; Fluorescence; Phenylurea Compounds; Photosynthesis; Photosystem II Protein Complex; Plant Leaves; Seasons; Sunlight; Time Factors; Ultraviolet Rays

Ameliorative effects of ethylenediurea (N-[2-(2-oxo-1-imidazolinidyl) ethyl]-N' phenylurea, abbreviated as EDU) against ozone stress were studied on selected growth, biochemical, physiological and yield characteristics of palak (Beta vulgaris L. var Allgreen) plants grown in field at a suburban site of Varanasi, India. Mean eight hourly ozone concentration varied from 52 to 73 ppb which was found to produce adverse impacts on plant functioning and growth characteristics. The palak plants were treated with 300 ppm EDU at 10 days after germination at 10 days interval up to the plant maturity. Lipid peroxidation in EDU treated plants declined significantly as compared to non-EDU treated ones. Significant increment in F(v)/F(m) ratio in EDU treated plants as compared to non-EDU treated ones was recorded. EDU treated plants showed significant increment in ascorbic acid contents and reduction in peroxidase activity as compared to non-EDU treated ones. As a result of the protection provided by EDU against ozone induced stress on biochemical and physiological characteristics of palak, the morphological parameters also responded positively. Significant increments were recorded in shoot length, number of leaves plant(-1), leaf area and root and shoot biomass of EDU treated plants as compared to non-EDU treated ones. Contents of Na, K, Ca, Mg and Fe were higher in EDU treated plants as compared to non-EDU treated ones. The present investigation proves the usefulness of EDU in partially ameliorating ozone injury in ambient conditions.

Topics: Air Pollutants; Antioxidants; Ascorbic Acid; Beta vulgaris; Biomass; Chlorophyll; Environmental Monitoring; Lipid Peroxidation; Ozone; Peroxidase; Phenylurea Compounds; Plant Leaves; Plant Shoots

Treatments with ethylenediurea (EDU) protect plants from ozone foliar injury, but the processes underlying this protection are poorly understood. Adult ash trees (Fraxinus excelsior), with or without foliar ozone symptoms in previous years, were treated with EDU at 450 ppm by gravitational trunk infusion in May-September 2005 (32.5 ppm h AOT40). At 30-day intervals, shoot growth, gas exchange, chlorophyll a fluorescence, and water potential were determined. In September, several biochemical parameters were measured. The protective influence of EDU was supported by enhancement in the number of leaflets. EDU did not contribute its nitrogen to leaf tissue as a fertiliser, as determined from lack of difference in foliar N between treatments. Both biochemical (increase in ascorbate-peroxidase and ascorbic acid, and decrease in apoplastic hydrogen peroxide) and biophysical (decrease in stomatal conductance) processes regulated EDU action. As total ascorbic acid increased only in the asymptomatic trees, its role in alleviating O(3) effects on leaf growth and visible injury is controversial.

Topics: Air Pollutants; Ascorbic Acid; Chlorophyll; Chlorophyll A; Ecology; Fraxinus; Nitrogen; Oxidants, Photochemical; Ozone; Peroxidase; Phenylurea Compounds; Pigmentation; Plant Shoots; Plant Stomata; Plant Transpiration