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1.
Allouche Y Warleta F Campos M Sánchez-Quesada C Uceda M Beltrán G Gaforio JJ 《Journal of agricultural and food chemistry》2011,59(1):121-130
This research aimed to investigate erythrodiol, uvaol, oleanolic acid, and maslinic acid scavenging capacities and their effects on cytotoxicity, cell proliferation, cell cycle, apoptosis, reactive oxygen species (ROS) level, and oxidative DNA damage on human MCF-7 breast cancer cell line. The results showed that erythrodiol, uvaol, and oleanolic acid have a significant cytotoxic effect and inhibit proliferation in a dose- and time-dependent manner. At 100 μM, erythrodiol growth inhibition occurred through apoptosis, with the observation of important ROS production and DNA damage, whereas uvaol and oleanolic acid growth inhibition involved cell cycle arrest. Moreover, although all tested triterpenes did not show free radical scavenging activity using ABTS and DPPH assays, they protected against oxidative DNA damage at the concentration 10 μM. Uvaol and oleanolic and maslinic acids, tested at 10 and 100 μM, also reduced intracellular ROS level and prevented H(2)O(2)-induced oxidative injury. Overall, the results suggest that tested triterpenes may have the potential to provide significant natural defense against human breast cancer. 相似文献
2.
DEHP对土壤蚯蚓氧化胁迫及DNA损伤的研究 总被引：3，自引：0，他引：3
土壤环境中的酞酸酯污染日益严重,为了探讨和分析典型酞酸酯邻苯二甲酸二(2-乙基己基)酯(Di(2-ethylhexyl)phthalate,DEHP)对土壤动物的生态毒理效应,以赤子爱胜蚓为指示生物,暴露于DEHP浓度为CK、0.1、1、10、50 mg kg~(-1)人工土壤中,并于染毒后的7、14、21、28d取样测定。通过蚯蚓体内的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物(POD)、谷胱甘肽转移酶(GST)等指标反映DEHP对蚯蚓的氧化激活程度,通过活性氧自由基(ROS)的含量反映DEHP对蚯蚓的细胞毒性,通过丙二醛(MDA)含量和Olive尾矩反映DEHP对蚯蚓的遗传毒性,从多个角度评价DEHP对蚯蚓的生态毒理效应。结果表明:(1)在DEHP的刺激下,各浓度组蚯蚓的SOD、CAT、POD、GST活性均呈激活状态,表明DEHP对蚯蚓的抗氧化酶有诱导作用;(2)DEHP影响蚯蚓的ROS含量,各染毒处理组与对照组相比均升高且差异性明显,表现出明显的剂量—效应关系;(3)对比各染毒处理组之间的数据,DEHP对蚯蚓MDA含量的影响无明显规律;(4)DEHP可使蚯蚓GST呈激活状态,表明中高浓度的DEHP对蚯蚓GST具有诱导作用;(5)DEHP能够引起蚯蚓体腔细胞DNA的损伤,且随着浓度的增加,Olive尾矩值随之增加,说明DNA损伤程度与DEHP浓度之间具有剂量-效应关系。从实验结果可以看出,DEHP可以对蚯蚓机体和DNA造成一定程度的损伤,表现出较强的生态毒理效应。 相似文献
3.
Four-year old Norway spruce (Picea abies (L.) Karst.) trees were pretreated at low and high water supply, and then placed into a growth chamber containing four compartments so that two levels of ozone exposure, 0.02 and 0.4 Μl l?1, could be replicated. They were exposed to ozone and drought stress for 59 days, and water use was determined by periodic weighing. Small effects of ozone treatment were detected on new shoot dry weight, and water use by trees receiving the high ozone treatment appeared higher. Both visual symptoms and ethylene biosynthesis showed that drought stress reduced damage to trees exposed to high ozone. Ethylene emission and 1-aminocyclopropane-1-carboxylic acid (ACC) levels increased after 18 days of exposure to 0.4 Μl l?1 ozone, while visual symptoms were seen at 30 days. After 59 days of exposure to the combined stresses, ethylene and ACC levels were lower, but showed an ozone x water interaction. Most ethylene and ACC were produced by wet trees at high ozone concentration, but dry trees also had high ethylene and ACC levels at low ozone. Levels of needle malonyl-ACC (MACC) were not significantly affected by treatment, and did not change with time, but root MACC levels, which were twice needle levels, were high in wet trees at high ozone concentration, but also high in dry trees at low ozone concentration. These results suggest that drought stress occurring during ozone exposure could be expected to reduce damage to young Norway spruce, and that this damage may be related to ethylene biosynthesis. 相似文献
4.
Three bush bean cultivars (Lit, Groffy and Stella) were grown under four levels of ozone exposure (ambient air+50 ppb O3 ambient air+25 ppb O3, ambient air and charcoal filtered air) in open- top chambers. Number and leaf injury statistics showed significant reduction in the number of healthy leaves as the level of O3 increased. The area based leaf injury percentages of the cvs. Lit, Groffy and Stella were 69.8, 57.9 and 71.1% at the highest O3 level, 24.1, 19.6 and 30.3% at the 2nd highest O3 level, and 4.5, 0.7 and 5.6% at the ambient air, respectively. The plants grown in the filtered air revealed no injury symptoms. The stomatal conductances were found to decrease gradually in each cultivar as the O3 level increased. At the highest O3 level, Chlorophyll fluorescence measurements on the 2nd leaf from the top on 24th day of exposure resulted in significantly the highest Fv/Fm values, the lowest f0 and the highest Fm values whereas the 4th leaf showed the smallest Fm and correspondingly the smallest Fv/Fm values. This is an indication of photosystem II damage after accumulation of a high ozone dose in the 4th leaf. The photosynthetic rate of the 2nd leaf measured on 30th day of exposure was comparatively higher at the highest exposure but the data taken from the same leaf on 40th day of exposure showed significantly lower photosynthetic rate than the plants in ambient air. Both chlorophyll fluorescence and photosynthetic measurements indicated that ozone stressed leaves experience a stimulation of photosynthesis (possibly due to increased assimilate demand) prior to irreversible damage. Bush bean leaves need to accumulate a critical ozone dose(an AOT40 of presumably > 18 ppm-h) for reduction of the photosynthetic capacitys. 相似文献
5.
Environmental stresses present major challenges in our quest to achieve sustainable food production. The reactions of plants to environmental stresses are complex and involve many kinds of physiological and biochemical responses. Stress causes multifarious adverse effects in plants. Production of a family of reactive oxygen species (ROS) is a common phenomenon. When plants are subjected to environmental stress, the balance between the production of ROS and the quenching activity of antioxidants is upset, often resulting in an oxidative damage. Plants with high levels of antioxidant enzyme activity are reported to have greater resistance to this oxidative damage. The activities of component enzymes or the antioxidant levels are usually only double in response to many stress situations. This rather moderate response might be understood if we consider that the system is geared to self-destruction when it comes under threat. Understanding the mechanisms by which plants perceive environmental signals and transmit the signals to cellular machinery to activate adaptive responses is of fundamental importance to biology. The present review is focusing on ROS generation and plant defenses to them. 相似文献
6.
An H Zhai Z Yin S Luo Y Han B Hao Y 《Journal of agricultural and food chemistry》2011,59(8):3851-3856
Lactic acid bacteria (LAB) are generally sensitive to oxidative stress caused by reactive oxygen species (ROS). Antioxidant enzymes, especially superoxide dismutase (SOD) and catalase (CAT), can protect against ROS by eliminating superoxide and H(2)O(2), respectively. Lactobacillus rhamnosus is a valuable probiotic starter culture but is deficient in both SOD and CAT, and is thus likely to suffer from oxidative stress in industrial fermentation. To confer high level of oxidative resistance on L. rhamnosus , the SOD gene sodA from Streptococcus thermophilus and CAT gene katA from L. sakei were coexpressed in L. rhamnosus AS 1.2466. The enzyme activities of SOD and CAT were 147.80 ± 1.08 U/mg protein and 2.53 μmol of H(2)O(2) /min/10(8) cfu, respectively, in the recombinant L. rhamnosus CS. After incubation with 10 mM H(2)O(2), the survival ratio of L. rhamnosus CS was 400-fold higher than that of L. rhamnosus CAT. In long-term aerated conditions, viable cells of L. rhamnosus CS remained ～10(6) cfu/mL after incubation for 7 days, while no living cells of the control were detected. These results showed that the cooperation between SOD and CAT could significantly enhance oxidative resistance in L. rhamnosus . To our best knowledge, this is the first report of two synergistic antioxidant genes being coexpressed in the same Lactobacilli. 相似文献
7.
Crop productivity is impaired by stress factors, biotic or abiotic. The main are pathogens, diseases, insects, cold, heat, salinity, drought, radiation and others. Among these unfavorable conditions, drought is one of the main occurrences and negatively affects crop development. This environmental adversity generally induces the accumulation of reactive oxygen species (ROS). These molecules lead to oxidative stress, and at high levels cause cell effects, like loss of organelle functions, electrolyte leakage, and reduction in metabolic efficiency. High concentration of ROS in cells can still cause molecular damage that include damage in proteins, amino acids, and lipids, and even lead to cell death. To neutralize these damages, plants increase enzymatic antioxidant activity and non-enzymatic antioxidant contents. ROS are essential to life in plants, and at basal levels performs cellular functions, such as signaling and defense responses. Here, we focus on the ROS production, the involvement and damages of these species in water deficit condition, changes in activity of antioxidant enzymes and non-enzymatic antioxidant contents in plants under drought stress. In addition, the signaling reactions of ROS under stress water restriction, changes on yield components of species under water deficit and the antioxidant genes involved in plant responses to stress were also addressed. 相似文献
8.
为了探究低温等离子体活化水 (cold plasma activated water, PAW) 对丁香假单胞杆菌猕猴桃致病变种 (Pseudomonas syringae pv. actinidiae, PSA) 的抗菌活性和潜在机制。该研究通过介质阻挡放电(dielectric barrier discharge, DBD) 低温等离子体发生装置制备不同激活时间的PAW,考察放电时间与杀菌效果之间的关系。此外,通过评估PSA形态特征,细胞粒径、DNA、细胞膜损伤情况和胞内活性氧积累 (reactive oxygen species,ROS) 情况探究PAW对PSA的杀菌机制。结果表明：PAW对PSA的杀灭效果与PAW激活时间呈依赖性,与对照相比PAW处理120 s后,PSA显著 (P<0.05) 减少了4.38 lg (CFU/mL)。扫描电子显微镜 (field emission scanning electron microscope, FESEM) 结果清楚地表明,由于PAW处理,PSA细胞发生了明显的质壁分离。荧光染色结果显示,PSA细胞DNA、膜渗透屏障被破坏程度、内容物泄漏量和ROS积累量与PAW激活时间表现为正相关关系。因此,推测PAW由于自身酸性、较高的氧化还原电位 (oxidation-reduction potential, ORP),以及水性活性物质导致细胞的氧化损伤,而且这可能是杀灭PSA的主要原因。研究结果可为PAW控制猕猴桃细菌性溃疡病提供参考。 相似文献
9.
Experiments were conducted in which sugarbeet plants (Beta vulgaris L. cv. Saxon) with 2 to 3 leaves were exposed to a simulated 2 day ozone episode (100 nl l?1, 7 h d?1). Three days later, the plants were sprayed with field rate phenmedipham (1.14 kg a.i. ha?1) and growth analysis conducted 7 days later indicated an antagonistic interaction was occurring. Physiological and biochemical studies were undertaken to determine the nature of this antagonism. Treatment with phenmedipham increased the ratio of transpiration to photosynthetic rates within 2 days of spraying, whilst exposure to ozone had no effect. When the two treatments were combined, water use efficiency was not significantly different from that when phenmedipham was applied alone. In contrast, trends in the membrane permeability after treatment, indicated that the response of plants exposed to ozone followed by treatment with the herbicide, was intermediate between that of the herbicide (high permeability) and ozone (low permeability). Furthermore, when the two treatments were combined the results of antioxidant enzyme assays indicated greater than expected activities of enzymes which are mainly cytosolic, eg. guaiacol peroxidase, as well as a similar increase in the activity of the mainly chloroplastic superoxide dismutase. Treatment with ozone alone and phenmedipham alone only slightly increased superoxide dismutase. Ozone may therefore induce the activities of these protective enzymes. Thus, when another oxidative stress, such as the photosystem II inhibitor phenmedipham, was applied the plants could then respond more quickly and showed less herbicide visible damage. 相似文献
10.
土霉素（Oxytetrac ycline,简称OTC）是养殖业中广泛使用的药物之一,由于大量使用,已在水环境中不断被检出,其对水生生物及人类可能产生的影响已经引起人们广泛关注。采用室内染毒实验方法,研究了土霉素对典型淡水鱼类日本锦鲫肝脏抗氧化防御系统的影响,分析暴露于不同浓度（0、0.01、0.05、0.1、0.5、1.0、5.0、10mg·L-1）的OTC溶液15d后鱼体肝脏中ROS、MDA、SOD、CAT和谷胱甘肽等指标,探讨其潜在的致毒机制。结果表明,ROS信号强度在高浓度组（5mg·L-1和10mg·L-1）与对照相比分别减少44.2%和32.5%,呈显著性差异;MDA含量在0.1mg·L-1和5mg·L-1下显著减少,分别减少41.7%和52.3%;SOD活性在0.01mg·L-1下显著性增加32.4%,CAT和GST活性呈低浓度被诱导、高浓度被抑制的趋势;GSH和GSSG含量的变化趋势相似,呈先减少后增加的趋势（P〈0.05）。上述结果表明低浓度OTC对日本锦鲫产生氧化应激,诱导了肝脏抗氧化防御系统,但高浓度下清除氧自由基的作用大于其氧化应激毒性,从而使得鱼体氧化应激程度减轻。抗氧化防御系统酶活性的变化只能间接反映污染物对生物造成应激效应的程度,要弄清楚OTC的致毒机制仍需进一步研究。 相似文献
11.
以重金属超富集植物龙葵为试验材料,分析了油菜素内酯(BR)对幼苗镉(Cd)毒害耐受性影响的生理机制。Cd毒害导致龙葵幼苗出现氧化伤害,同时降低了幼苗超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性。表油菜素内酯(eBL,人工合成的BR)处理增加了龙葵幼苗对Cd毒害的敏感性,与eBL处理的结果相反,施用油菜素唑(Brz,BR合成的特异性抑制剂)增加了Cd毒害下龙葵幼苗的抗氧化酶活性,降低了ROS的累积,减少了幼苗的氧化伤害。Brz处理后幼苗株高和根长较Cd处理的对照分别增加29%和28%,MDA水平和Evans blue染色程度较Cd处理的对照分别降低37%和20%,进一步证明BR增加了Cd毒害下龙葵幼苗的氧化伤害,从而加重了Cd胁迫对幼苗生长的抑制作用。表明BR通过降低龙葵幼苗的抗氧化能力,增加了幼苗对Cd毒害的敏感性。 相似文献
12.
Bellion P Hofmann T Pool-Zobel BL Will F Dietrich H Knaup B Richling E Baum M Eisenbrand G Janzowski C 《Journal of agricultural and food chemistry》2008,56(15):6310-6317
Apples represent a major dietary source of antioxidative polyphenols. Their metabolic conversion by the gut microflora might generate products that protect the intestine against oxidative damage. We studied the antioxidant effectiveness of supernatants of fermented apple juice extracts (F-AEs, 6 and 24 h fermentation) and of selected phenolic degradation products, identified by HPLC-DAD-ESI-MS. Cell free antioxidant capacity of unfermented apple juice extracts (AEs) was decreased after fermentation by 30-50%. In the human colon carcinoma cell line Caco-2, F-AEs (containing <0.5% of original AE-phenolics) decreased the reactive oxygen species (ROS) level more efficiently than the F-blank (fermented without AE) but were less effective than the respective AEs. Similarly, antioxidant effectiveness of individual degradation products was lower compared to respective AE constituents. Glutathione level was slightly increased and oxidative DNA damage slightly decreased by fermented AE03, rich in quercetin glycosides. In conclusion, F-AEs/degradation products exhibit antioxidant activity in colon cells but to a lesser extent than the respective unfermented AEs/constituents. 相似文献
13.
Esteban Alcántara Manuel D. de la Guardia Inmaculada Montilla Francisco J. Romera 《Journal of plant nutrition》2013,36(12):2245-2255
The initial objective was to confirm evidence, obtained from field grown plants, for iron (Fe) accumulation in leaves under ozone exposure. Tobacco plants were grown in pots under either open air or growth chamber conditions. The ozone-sensitive cultivar Bel W3 showed symptoms of ozone injury only when grown outside, while the cultivar Virginia never developed symptoms. In both cultivars, basal leaves of plants grown outside had higher concentration of Fe, but not of manganese (Mn) or zinc (Zn), than those from the growth chamber. Results suggest an interference of the oxidative stress with the mechanisms regulating Fe homeostasis. A second objective was to test whether differences in tolerance to ozone correspond with differences in tolerance to Fe toxicity. Iron toxicity was induced by supplying an excess of Fe-EDTA to plants, grown hydroponically in a growth chamber, upon partial root cutting. Symptoms in leaves were more severe in Bel W3 than in Virginia, which suggested that mechanisms of tolerance to ozone were also effective against Fe toxicity. In both cultivars, a good correlation was determined between Fe accumulation and ethylene production in the leaves. 相似文献
14.
Mechanisms of exogenous nitric oxide and 24-epibrassinolide alleviating chlorosis of peanut plants under iron deficiency 总被引：1，自引：1，他引：0
Iron(Fe) is a crucial transition metal for all living organisms including plants; however, Fe deficiency frequently occurs in plant because only a small portion of Fe is bioavailable in soil in recent years. To cope with Fe deficiency, plants have evolved a wide range of adaptive responses from changes in morphology to altered physiology. To understand the role of nitric oxide(NO) and 24-epibrassinolide(EBR) in alleviating chlorosis induced by Fe deficiency in peanut(Arachis hypogaea L.) plants, we determined the concentration of chlorophylls, the activation, uptake, and translocation of Fe, the activities of key enzymes, such as ferric-chelate reductase(FCR),proton-translocating adenosine triphosphatase(H~+-ATPase), and antioxidant enzymes, and the accumulation of reactive oxygen species(ROS) and malondialdehyde(MDA) of peanut plants under Fe sufficiency(100 μmol L~(-1)ethylenediaminetetraacetic acid(EDTA)-Fe) and Fe deficiency(0 μmol L~(-1)EDTA-Fe). We also investigated the production of NO in peanut plants subjected to Fe deficiency with foliar application of sodium nitroprusside(SNP), a donor of NO, and/or EBR. The results showed that Fe deficiency resulted in severe chlorosis and oxidative stress, significantly decreased the concentration of chlorophylls and active Fe, and significantly increased NO production. Foliar application of NO and/or EBR increased the activity of antioxidant enzymes, superoxide dismutase,peroxidase, and catalase, and decreased the ROS and MDA concentrations, thus enhancing the resistance of plants to oxidative stress.Application of NO also significantly increased Fe translocation from the roots to the shoots and enhanced the transfer of Fe from the cell wall fraction to the cell organelle and soluble fractions. Consequently, the concentrations of available Fe and chlorophylls in the leaves were elevated. Furthermore, the activities of H~+-ATPase and FCR were enhanced in the Fe-deficient plants. Simultaneously,there was a significant increase in NO production, especially in the plants that received NO, regardless of Fe supply. These suggest that NO or EBR, and, especially, their combination are effective in alleviating plant chlorosis induced by Fe deficiency. 相似文献
15.
Over a period of two years greenhouse experiments were carried out to quantify the interaction ozone exposure × water stress in winter wheat (Triticum aestivum L. cv. Perlo). Assessment of effects carried out on various yield parameters showed that abundant water supply made the plants most sensitive to ozone exposure. In well-watered plants (75%) of soil water capacity, s.w.c.), the AOT40 ozone exposure doses of 26.8 and 24.9 μmol mol-1 hr-1 (ppm.h) caused grain yield reductions by 35 and 39%. No reductions of yields were observed at severe water stress (35% of s.w.c.) condition. The decrease in ozone responsiveness under drought can be explained by a distinct reduction in ozone uptake (18 vs. 2 mmol m-2 in well-watered vs. severely stressed plants at the same ozone exposure). The calculations of ozone uptake were based onrepeated measurements of leaf conductance. Generally curvi-linear regression functions explained the dependence of relative yield on ozone and on water stress better than multiple simple linear regression functions. The consideration of ozone uptake instead of ozone exposure improved the performances of the models further. For explaining grain yield, 96.8% of the variances could be explained by a model resulting from curvi-linear regression fitting. A suggestion for calculating correction factors to modify critical levels in the case of limited water supply is presented. 相似文献
16.
Cosson Richard P. Amiard-Triquet Claude Amiard Jean-Claude 《Water, air, and soil pollution》1991,(1):555-567
Our own results and a literature review led us to reconsider the detoxifying function of MTs in living organisms. Despite the fact that many authors have observed a synthesis or a level increase of MTs as a response to toxic metal uptake, arguments exist which tend us to give to MTs a strict zinc homeostasic function. Many experiments have been conducted using non-natural routes of exposure and/or concentrations far from those observed even in heavily polluted environments. Zinc is the only metal for which a primary induction has been established. Correlations between zinc and MTs levels are frequently observed, specially at the early stages of life. Our knowledge about metallic cluster structure and our experimental results about inter-metallic competition for binding-sites on the apoprotein, support the idea of substitution processes instead of de novo synthesis in most cases of contamination, leading frequently to acclimation. 相似文献
17.
Critical levels of tropospheric ozone, established for the protection of crops and other plants, are now reported as being exceeded over large forested areas, giving rise to the need for an extensive monitoring program to confirm ambient levels within the forest and to detect related forest health effects. The requirement for an inexpensive monitor that can be used in remote locations prompted the development of the Can Oxy PlateTM passive ozone monitor and a monitoring protocol by the air pollution research group of the Canadian Forest Service, Forest Health Network. The monitors underwent initial trials in 1996 and operational trials during 1997 that involved two 2-3 week mid summer exposures in the canopy at selected forest health monitoring plots across Canada, and at adjacent forest openings. In both trials monitors were also co-located with the nearest instrumental ozone monitor. This allowed for the production of a field calibration for quality assurance assessment under field conditions. Results from 1996 indicate highly significant correlations with accumulated ambient ozone concentrations from the instrumental monitors at the co-located sites (r=0.88, p=0.0002). However, no such relationship was found between these sites and the forest plots which were up to 200 kilometres away. This may indicate spatial heterogeneity in ozone exposure between the continuous air quality monitoring sites and the forest plots. This information, together with our knowledge that strong gradients of ozone exposure are found within the canopy, underlines the importance of in situ monitoring of ozone exposure of forest health plots at risk to ozone effects. 相似文献
18.
Pereira-Caro G Sarriá B Madrona A Espartero JL Goya L Bravo L Mateos R 《Journal of agricultural and food chemistry》2011,59(11):5964-5976
Alkyl hydroxytyrosyl ethers (methyl, ethyl, propyl, and butyl ethers) have been synthesized from hydroxytyrosol (HTy) in response to the increasing food industry demand of new lipophilic antioxidants. Having confirmed that these compounds reach portal blood partially unconjugated and thus are effectively absorbed, their potential antioxidant activity was evaluated in the human hepatocarcinoma cell line (HepG2). The effects of 0.5-10 μM alkyl hydroxytyrosyl ethers on HepG2 cell integrity and redox status were assessed as well as the protective effect against oxidative stress induced by tert-butylhydroperoxide (t-BOOH). Cell viability (Crystal violet) and cell proliferation (BrdU assay) were measured as markers of cell integrity, concentration of reduced glutathione (GSH), generation of reactive oxygen species (ROS), and activity of antioxidant enzymes glutathione peroxidase (GPx) and glutathione reductase (GR) as markers of redox status and determination of malondialdehyde (MDA) as a marker of lipid peroxidation. Direct treatment of HepG2 with alkyl hydroxytyrosyl ethers induced slight changes in cellular intrinsic antioxidants status, reducing ROS generation and inducing changes in GPx and GR activities. Pretreatment of HepG2 cells with alkyl hydroxytyrosyl ethers counteracted cell damage induced by t-BOOH, partially after 2 h and completely after 20 h, by increasing GSH and decreasing ROS generation, MDA levels, and antioxidant enzyme (GPx and GR) activity. According to these results the alkyl hydroxytyrosyl ethers show clear protective effects against oxidative stress, related to their lipophilic nature, that are similar to or even higher than those of their precursor, HTy. 相似文献
19.
M. Brown R. Cox K. R. Bull H. Dyke G. Sanders D. Fowler R. Smith M. R. Ashmore 《Water, air, and soil pollution》1995,85(3):1485-1490
In Britain wheat is an important crop accounting for 41% of the total cereal production. In this study ozone concentrations for 1989 estimated as described in Part 1 of the paper are integrated with the estimated wheat distribution to derive a detailed estimate of the impact of ozone on wheat yields at a fine spatial scale (1km × 1km). These data provide estimates for calculating regional and national yield losses. The methodology can be applied to other crop species. Recent research on a range of crops has established relationships between the economic yield loss for certain crops, including wheat, and ozone exposure. Exposure is described as the accumulated exposure above a threshold experienced during the daylight hours (AOT). Critical AOT values are derived from yield exposure relationships which show linear reductions of yield loss with increasing ozone concentrations. This study has made use of land cover data from remotely sensed imagery at 25m resolution and nationally collected agricultural statistics for counties. These data were combined using an areal interpolation technique to provide more spatially articulate estimates of the location and intensity of wheat production. The results demonstrate the economic importance of ozone as a pollutant. Wheat yield losses attributed to ozone vary between different parts of the country but, for years when ozone levels are high, yield losses are likely to be significant in some areas. 相似文献
20.
Field fumigation studies conducted in grassland, oak, aspen, and conifer, communities established the injury threshold of prevalent plant species to ozone. Several important species, including Bromus tectorum, Quercus gambelii, and Populus tremuloides, were injured by a single 2-hours exposure to 15 pphm ozone. Over half the perennial forbs and woody species studied were visibly injured at concentrations of 30 pphm ozone or less. It is postulated that lower concentrations at prolonged or repeated exposures to ozone may impair growth and affect community vigour and stability. Continued exposure of natural plant communities to ozone is expected to initiate major shifts in the plant composition of communities. 相似文献