Ozone sensitivity of Phaseolus vulgaris in relation to cultivar differences,growth stage and growing conditions

Exposure of Phaseolus vulgaris cv. Lit to ambient ozone caused a 14% pod yield reduction in 1994. This yield loss was assessed by comparing plants that were protected against ozone by treatment with EDU (ethylenediurea) with unprotected plants, both cultivated in pots with a continuous water supply. The plants had experienced an AOT40 of 8135 ppb.h during their growth. However, plant response to ozone depends on a large number of environmental and plant-specific conditions. Visible injury increased mainly after flowering and was much less severe on soil-grown bean cultivars (Lit, Stella and Groffy) not receiving additional water. Ozone fumigations in closed chambers before or after flowering proved that the growth stage during which the plants are exposed also plays a very important role with regard to injury development. Plants seem to be more susceptible during the generative growth stage and the relative cultivar sensitivity was related to the developmental stage during fumigation. However with regard to yield effects the timing of the ozone exposure seems to be less important.     

Responses of Young Trees (Five Species in a Chamber Exposure) to Near-Ambient Ozone Concentrations

This investigation is intended to add to the quantitative information about the sensitivity of European deciduous tree species to environmentally realistic ozone (O₃) exposure in respect to the established critical level of an AOT40 of 10 ppm.h (6-month growing season, daylight hours). Cuttings (without leaves) of Fagus sylvatica L., Sorbus aucuparia, L., Carpinus betulus L., Fraxinus excelsior L., and cuttings and seedlings of Prunus serotina Ehrh. were exposed during one growing season either to filtered air, to which 50 % of ambient O₃ concentration was added, or to 50 % + 30 ppb O3, resulting in a final AOT40 of 0.3 and 20.7 ppm.h, respectively. The foliage formed per tree varied between and within the species, but was not significantly modified by O₃, whereas the number of symptomatic leaves per tree significantly increased in the 50 % + 30 ppb O₃ regime. By mid July light-green spots appeared in the leaves (except C. betulus), which developed into stippling (F. excelsior), red (P. serotina) or necrotic spots by September. The CO₃-assimilation rate decreased more with increasing visual symptoms (earliest in 20- day-old leaves) than with age-dependent leaf discoloration in F. sylvatica, F. excelsior, and P. serotina (not in C. betulus). The dark-adapted photosystem II quantum yield (Fv/Fm) slightly declined with leaf age, but a considerable reduction became apparent in 107-day-old leaves with O₃-symptoms only. By late morning yield reduction in light-adapted leaves were exaggerated in such leaves from the 50 % + 30 ppb O₃ regime. The above mentioned responses were not reflected in significant changes of the net biomass production during the experiment. The critical level, therefore, is based on visual and functional symptoms rather than on production.     

Effects of ambient gaseous pollutants on photosynthesis,growth, yield and grain quality of selected crops grown at different sites varying in pollution levels

In recent decades, ambient gaseous pollution has increased due to anthropogenic activities worldwide. The studies to evaluate the adverse effects of ambient pollutants on commonly grown food crops are still limited, especially in Asian countries like Pakistan. The present study was conducted to measure the ambient pollutants in different sites of Faisalabad and their impact on growth and yield of wheat, mung bean and peas. Plants were grown in pots and placed at three sites named as control (Wire house of Government College University, Faisalabad), low pollution (LP) (Farm Area of Ayub Agricultural Research Institute) and high pollution (HP) (GT Chowk, Faisalabad) sites. Results showed that ambient ozone (O₃) concentration was highest at HP site followed by LP site and was below AOT40 in control site. Ambient pollutants caused foliar injury in crops and decreased plant height, leaf area, biomass and grain yield. Pollutants caused a reduction in photosynthetic pigments, stomatal conductance and net photosynthetic rate and grain protein contents in all three crops. In conclusion, the ambient O₃ level was highest at HP site, this current O₃ level and other pollutants decreased the growth and yield of important food crops.     

Physiological Effects of Exposure to Arsenic,Mercury, Antimony and Selenium in the Aquatic Moss Fontinalis antipyretica Hedw.

This study assessed the effect of ambient air pollution on leaf characteristics of white willow, northern red oak, and Scots pine. Willow, oak, and pine saplings were planted at sixteen locations in Belgium, where nitrogen dioxide (NO₂), ozone (O₃), sulfur dioxide (SO₂), and particulate matter (PM₁₀) concentrations were continuously measured. The trees were exposed to ambient air during 6 months (April–September 2010), and, thereafter, specific leaf area (SLA), stomatal resistance (R _s), leaf fluctuating asymmetry (FA), drop contact angle (CA), relative chlorophyll content, and chlorophyll fluorescence (F _v/F _m) were measured. Leaf characteristics of willow, oak, and pine were differently related to the ambient air pollution, indicating a species-dependent response. Willow and pine had a higher SLA at measuring stations with higher NO₂ and lower O₃ concentrations. Willow had a higher R _s and pine had a higher F _v/F _m at measuring stations with a higher NO₂ and lower O₃ concentrations, while oak had a higher F _v/F _m and a lower FA at measuring stations with a higher NO₂ and lower O₃ concentrations. FA and R _s of willow, oak, and pine, SLA of oak, and CA of willow were rather an indicator for local adaptation to the micro-environment than an indicator for the ambient air pollution.     

Inter- and Intra-specific Differences in the Response of Chinese Leafy Vegetables to Ozone

The response to ozone (O₃) of a range of Chinese leafy vegetables was investigated with respect to both inter- and intra-specific differences in sensitivity. In the interspecific experiment local Chinese cultivars of pak choi, rape, leaf mustard, leaf lettuce and coriander were fumigated with 90?ppb O₃ for 9?h daily for 22?C30?days. A similar fumigation was carried out using four different cultivars of pak choi. Sequential measurements were made of leaf injury, photosynthetic rate, stomatal conductance and chlorophyll fluorescence, together with dry weights at a final harvest. O₃ injury appeared as white or yellow blemishes on the leaf surface of all species. The first signs of injury were seen following only 3-days?? O₃ exposure (pak choi); the extent of injured leaf area increased over time for all species and cultivars, with 44.6% of the leaf area visibly injured for leaf mustard, the species with the greatest extent of injury, following 30-days?? exposure. Significant reductions in photosynthetic rate (22.7?C40.7%) and stomatal conductance (19.1?C33.1%) were found for all species and cultivars following O₃ exposure. Plant productivity was also reduced in O₃ compared to filtered air, with significant yield reductions for all species (11.1?C50.8% above-ground dry weight) as well as for all cultivars of pak choi (15.8?C28.1% above-ground dry weight). The mechanisms for observed impacts are discussed, together with the implications for current and future production of vegetables in the southern China province of Guangdong.     

Effects of Ozone and/or Soil Water Stress on Growth and Photosynthesis of Fagaus Crenata Seedlings

The effects of ozone (O₃) and soil water stress, singly and in combination, on the growth and photosynthesis of Fagus crenata seedlings were investigated. Four-year-old seedlings were exposed to charcoal-filtered air (< 5 nmol mol^?1 O₃) or 60 nmol mol^?1 O₃, 7 hours per day (11:00–18:00), for 156 days from 10 May to 11 October 1999 in naturally-lit growth chambers at 20/15 °C (6:00–18:00/18:00–6:00). During the same period, half of the seedlings in each gas treatment received 250 mL of water at the 3-day intervals (well-watered treatment), while the rest received 175 mL of water at the 3-day intervals (water-stressed treatment). The exposure of the seedlings to O₃ caused reductions in the leaf, stem, root and whole-plant dry weights. The net photosynthetic rate at 350 µmol mol^?1 CO₂, the maximum net photosynthetic rate at saturated CO₂-concentration, carboxylation efficiency of photosynthesis and Rubisco content were significantly reduced by the exposure to O₃. The soil water stress induced reductions in the stem, bud and whole-plant dry weights, transpiration rate and leaf water potential during the midday. The additive effects of O₃ and soil water stress were observed on the dry matter production, leaf gas exchange rates and leaf water potential. As a result, the whole-plant dry weight of the seedlings exposed to both stresses was markedly reduced compared with that of the seedlings exposed to charcoal-filtered air and grown in the well-watered treatment.     

Carbon Isotope Composition, Macronutrient Concentrations, and Carboxylating Enzymes in Relation to the Growth of Pinus halepensis Mill. When Subject to Ozone Stress

We present here the effects of ambient ozone (O₃)-induced decline in carbon availability, accelerated foliar senescence, and a decrease in aboveground biomass accumulation in the Aleppo pine (Pinus halepensis Mill.). Aleppo pine seedlings were continuously exposed in open-top chambers for 39 months to three different types of O₃ treatments, which are as follows: charcoal-filtered air, nonfiltered air (NFA), and nonfiltered air supplemented with 40 ppb O₃ (NFA+). Stable carbon isotope discrimination (??) and derived time-integrated c _i/c _a ratios were reduced after an accumulated ozone exposure over a threshold of 40 ppb (AOT40) value from April to September of around 20,000 ppb·h. An AOT40 of above 67,000 ppb·h induced reductions in ribulose-1,5-biphosphate carboxylase/oxygenase activity, aboveground C and needle N and K concentrations, the C/N ratio, Ca concentrations in twigs under 3 mm, and the aerial biomass, as well as increases in needle P concentrations and phosphoenolpyruvate carboxylase (PEPC) activity and the N and K concentrations in twigs under 3 mm. Macronutrients losses, the limitations placed on carbon uptake, and increases in catabolic processes may be the causes of carbon gain diminution in leaves which was reflected as a reduction in aboveground biomass at tree level. Stimulation of PEPC activity, the consequent decreased ??, and compensation processes in nutrient distribution may increase O₃ tolerance and might be interpreted as part of Aleppo pine acclimation response to O₃.     

Critical levels of O3 for wood production of European beech (Fagus sylvatica L.)

During recent decades, ozone (O₃) has gained much attention as a possible contributor to forest decline. Attempts have been made to set critical levels for O₃ in order to protect vegetation. Damage to vegetation seems to depend on the pattern of exposure. Episodic peaks followed by periods with low concentrations are more phytotoxic than exposures with generally elevated concentrations but without peaks. The present experiment aims to examine whether O₃ affects the wood production of beech seedlings. The seedlings were exposed to three different air pollution regimes: charcoal-filtered ambient air (CF), non-filtered ambient air (NF), and NF+30nl^1?l^?1 O₃ 8 hours day¹ during summer periods (NFO). Basal stem diameter was measured regularly during three growing seasons. The relative diameter increase was significantly reduced with increased O₃ concentration. AOT40 is calculated for all treatments and evaluated in relation to the relative diameter growth.     

The Determination of Ozone in Ambient Air with Free Hanging Filters as Passive Samplers

This paper describes the use of dry free hanging filters, as passive samplers to determine ozone in the ambient air. The filters, with a diameter of 25?mm, were impregnated with 5,5??-disodium indigo disulphonate (IDS), a reagent for ozone. From the amount of reacted indigo compound, found on the filter, and the ozone concentration in the ambient air, a pseudo rate constant k ₁, of the reaction between ozone (O₃) and IDS on the filter, is calculated. The range of measurement is between 9 and 205???g/m³ ambient ozone. The dry filter method is specific for ozone, while the Dutch standard method NEN2789, based on an aqueous solution of IDS, has to be corrected for the presence of NO _x . From wind tunnel and field experiments, k ₁ proved to vary between 0.7 and 1.5?×?10^?6?m³?s^?1 (??g O₃)^?1 at wind velocities between 1 and 3?m/s and at an exposure time of 60?min. Within these conditions, ozone concentrations have been determined with free hanging filters in four busy streets in Yogyakarta, Indonesia and at two background sites using an average value of k ₁ of 1.2?×?10^?6. Subsequently, the traffic NO emission was estimated from the difference of the O₃ concentrations at both sides of a road. For an arbitrary situation, an NO emission of 255???g/s per metre road length was calculated. The filter method is inexpensive and practical, needs no electricity, is easily assembled and can be used to perform measurements in remote areas. It is shown here that this simple measurement technique may support air quality studies, e.g., in developing countries.     

Spatial and Temporal Ozone Pattern Concentrations in a NW Region of Spain

Measurements of ozone were carried out at two different sites in the area surrounding a thermal power plant located in the Northwest of Spain during 1993–1995. The concentration of O₃ in the ambient air varied from 6 to 257 μg m^-3 exhibiting a wide temporal, seasonal and spatial variation. On a few occasions 1-hr ozone concentration was more than 180 μg m^-3, which represents the maximum 1-hr limit of ozone in ambient air as prescribed by the European Commission.     

外源抗坏血酸对臭氧胁迫下水稻光合及生长参数的影响

为研究臭氧浓度变化对水稻生长的影响及外源抗坏血酸的防护作用,在田间原位条件下,利用开顶式气室(OTCs)研究了外源抗坏血酸对O3胁迫下水稻光合及生长参数的影响.结果表明:在O3胁迫下,叶片的光合色素含量、气体交换参数、净同化率、相对生长速率及粒/叶面积(cm2)均显著下降;喷施外源抗坏血酸后,叶绿素a含量、叶绿素a/叶绿素b以及水稻叶片的光合速率、蒸腾速率显著升高,而叶绿素b含量和气孔导度变化不显著;外源抗坏血酸对O3胁迫下水稻的净同化率、相对生长速率及粒/叶面积(cm2)影响比较显著,特别是粒/叶面积(cm2)的提高有利于水稻源、库协调发展,为提高水稻产量和改进品质奠定了物质基础.     

Modification of ozone effects on photosynthetic capacity of winter wheat (Triticum aestivum L. CV. perlo) at different levels of water availability

Attached leaves were used for the determination of the photochemical capacity by means of a portable fluorimeter. Repeated fluorescence measurements showed the negative effects of ozone on photochemical capacity and these negative effects increased with increasing ozone doses. But impairments of photochemical capacity were smallest if severe water stress co-occurred with ozone exposures. The upper leaf sides experienced more reduction of photochemical capacity in well-watered plants than the lower leaf sides, possibly by the additional effect of light stress on the upper leaf sides. In diurnal studies, a decline of F _v/F _m was observed at noontime and a recovery at evening in both control and ozone-fumigated leaves at two extreme water capacities (w.c.) (75% and 35% of w.c.). The extent of depression and recovery of F _v/F _m was not significantly varying. The oscillations of F _v/F _m could be due to short-term disturbances in the photosynthetic capacity, due to oxidative stress.     

地表臭氧浓度升高对麦田水热通量的影响

臭氧(O₃)浓度升高危害小麦生长,现有研究尚不清楚推广新的小麦品种能否减缓O₃对籽粒产量、农田蒸散和水分利用效率的负面效应,且研究O₃浓度升高对麦田水分利用效率的影响对农业用水管理具有重要意义。本研究利用完全开放式O₃浓度升高平台（O₃-FACE）,通过连续观测农田小气候特征,结合能量平衡法分析O₃浓度升高对麦田水热通量、小麦籽粒产量和田间水分利用效率的影响。结果表明：O₃浓度升高显著降低了开花后第32天小麦旗叶的叶绿素含量,降低了乳熟–成熟期的麦田潜热通量平均值和正午峰值,但影响幅度较小。O₃浓度升高对麦田平均水热通量及其分配无显著影响,也未影响籽粒产量、产量组成和田间水分利用效率。不同于10年前江淮地区主推的扬辐麦2号、烟农19和嘉兴002等品种,当前推广的农麦88表现出极强的O₃抗性。在O₃浓度不断升高背景下,种植农麦88有助于减缓O₃浓度升高对田间蒸散和水分利用效率的影响。     

Effects of Elevated Ozone Concentrations on Thai Jasmine Rice Cultivars (Oryza Sativa L.)

This study investigated the effects of O₃ on growth, yields and physiological characteristics of Thai Jasmine rice cultivars. Rice was exposed to O₃ for 7 h day^?1 in a closed chamber for 113 days, beginning from seedling until harvest. O₃ concentration in each chambers was controlled at 0 ppb, 50 ppb, 100 ppb, 150 ppb and at the ambient level. Effects of O₃ on leaf area index (LAI) became obvious at maturity when LAI significantly decreased in the treatments under elevated O₃ concentrations. Results in shoot biomass indicated that shoot length was more affected by O₃ than shoot dry weight. Root length rather than dry weight was significantly reduced in all cultivars. The most severe damage of O₃ was found in photosynthetic components, namely chlorophyll and carotenoid contents, and rate of net photosynthesis. Yield components were also strongly affected by O₃. The highest reduction in filled seed per ear was found in the Pathumthani 1 cultivar by 78% when it was exposed to 150 ppb O₃ compared to the control (0 ppb). Similarly, 100-grain weight was also reduced as much as 12.3% in this cultivar.     

Effects of Two Different Ozone Exposure Regimes on Chlorophyll and Sucrose Content of Leaves and Yield Parameters of Sugar Beet (Beta Vulgaris L.) and Rape (Brassica Napus L.)

Sugar beet (Beta vulgaris cv. Loretta) and rape (Brassica napus cv. Licolly) plants were exposed under equaldose conditions in closed fumigation chambers under twodifferent ozone (O₃) pattern: Var₁₃₀ (17:00–09:00 h: 40 μg O₃ m^-3; 09:00–17:00 h: 130μgO₃ m^-3) and Var₂₂₀ (16:00-12:00 h: 40 μgO₃ m^-3; 12:00–16:00 h: 220μg O₃ m^-3).Control plants were exposed under carbon filtered airconditions (ozone free, CF-control). Sugar beet plants wereexposed four weeks each during 6-leaf-stage and lateralgrowth respectively. Rape plants were exposed for 14 daysduring flowering (f) or as young plants (y). In between andafter the end of exposure, plants were kept in carbonfiltered air (CF; < 10 μg O₃ m^-3). With respect to sucrose and chlorophyll content of leaves andseed weight, rape plants were most sensitive duringflowering. Under equal dose conditions, the most pronouncedeffects on chlorophyll and sucrose content of leaves as wellas fresh weight of taproots (CF: 100%; Var₁₃₀: 97%;Var₂₂₀: 83%) and of rape seeds (CF: 100%; y:Var₁₃₀: 122%; Var₂₂₀: 99%; f: Var₁₃₀: 84%;Var₂₂₀: 78%) were detected after exposure under shorttime high ozone peak conditions (Var₂₂₀). Howeverglucose content in taproots (CF: 100%; Var₁₃₀: 43%;Var₂₂₀: 79%) and fatty acid content in rape seeds wasaffected most after exposure to moderate ozone peaks(Var₁₃₀). Var₁₃₀-plants seem to recover better fromozone stress than Var₂₂₀-plants, but glucose content oftaproots and fatty acid content of rape seeds indicate long-lastingeffects especially in Var₁₃₀-plants.Although experiments were conducted in a closed chambersystem it can be concluded, that current ozone concentrationscan induce adverse effects on these crops.     

Pigment Concentrations and Ratios of Aleppo Pine Seedlings Exposed to Ozone

Two-year-old Aleppo pine (Pinus halepensis Mill.) seedlings were exposed to ambient air+50 ppb O₃ in open-top chambers (24 hours/day, 7 days/week) during May-October 1997 and to ambient air+70 ppb O₃ from May 1998 onwards. One growing season fumigation with ozone did not affect the pigment concentrations of the current-year (c) needles, nor were there any differences in photosynthesis or stomatal conductance. In May 1998, however, a marked carry-over effect was seen in the chlorophyll a and b and total carotenoid concentrations of the O₃-fumigated one-year-old (c+1) needles. The chlorophyll a and b and total carotenoid concentrations of newly flushed needles of the O₃-fumigated seedlings also seemed to be slightly decreased, as was their net photosynthesis when compared to the values of the filtered-air control needles. The chlorotic mottle and the changes in chloroplast pigments and photosynthesis of the c and/or c+1 needles of the NFA+O₃3 seedlings in May 1998 indicate that frequent episodes of ozone concentrations of ≥100 ppb, especially when they also occur during the evening and night hours, as in some areas in southern Europe, may result in visible needle damage on Aleppo pine.     

Quantifying the fine scale (1km × 1km) exposure and effects of ozone. Part 1. Methodology and application for effects on forests

Surface ozone concentrations show very large local variability. This, in rural areas, is largely a consequence of the degree to which the surface air is decoupled from the bulk of the atmosphere by nocturnal and winter stability effects and of the aerodynamic roughness and topography of the countryside. Procedures have been developed to simulate these effects and have been used with O₃ data from a regional monitoring network to quantify exposure of vegetation to mean and peak O₃ concentrations. The index of exposure to potentially phytotoxic O₃ concentrations is the AOT40 (accumulated exposure over a threshold of 40 ppb) expressed in ppb.h. The accumulated exposure of crop and forest surfaces to ozone is shown to increase approximately linearly with altitude and along a gradient from 3000 ppb.h in north west Scotland to 7000 ppb.h in the south of England. The area of UK forest which exceeds the critical level for ozone effects (10⁴ ppb.h above 40 ppb) totals 2.0 × 10⁴ km² and represents 47% of afforested land. The areas affected include most of southern and central England and Wales and large plantation forests of Northumberland and the Scottish borders.     

Cultivar-Specific Response of Soybean (Glycine max L.) to Ambient and Elevated Concentrations of Ozone Under Open Top Chambers

Two cultivars of soybean (Pusa 9814 and Pusa 9712) were investigated to evaluate the impact of ambient and elevated concentrations of ozone (O₃) in a suburban site of India with and without application of 400 ppm ethylenediurea (EDU) in open top chambers having filtered air (FCs), non-filtered air (NFCs), and non-filtered plus 20 ppb O₃ (NFCs?+?20 ppb). Significant reductions were observed in various growth parameters, biomass accumulation, and yield attributes of soybean cultivars due to ambient O₃ in NFCs and elevated concentration of O₃ in NFCs?+?20 ppb. Reductions in all parameters were of lower magnitude in plants treated with EDU as compared to non-EDU treated plants. Yield (weight of seeds plant^?1) increased by 29.8% and 33% in Pusa 9712 and by 28.2% and 29.0% in Pusa 9814 due to EDU treatment in plants grown at ambient and elevated levels of O₃, respectively. The results clearly showed that (a) EDU can be effectively used to assess phytotoxicity of O₃ by providing protection against its deleterious effects, (b) EDU can be used for biomonitoring of O₃ in areas experiencing its higher concentrations, and (3) EDU is more effective against higher concentrations of O₃.     

Oxidant effects on forest tree seedling growth in the Appalachian mountains

Long range transport of episodic concentrations of O₃ into the Appalachian Mountains of Virginia was recorded in the summer season of 1979 and 1980. Continuous monitoring of O₃ indicated monthly averages of ? 0.05 ppm O₃ and several periods averaged ? 0.08 ppm O₃. Open-top chambers were used to test the effect of ambient doses of the pollutant on the growth of 8 planted forest tree species native to the area. Height growth was suppressed for all species at the end of the second growing season when grown in open plots (no chamber) and ambient chambers compared to those grown in charcoal-filtered air supplied chambers. Height growth trends of open < ambient chamber < filtered air chamber were consistent. Virginia pine and green ash were significantly taller (p=0.10) when grown within filtered air chambers. Tulip poplar and green ash manifested purple stippling on the adaxial leaf surface and sweetgum developed purple coloration under open or ambient chamber conditions; other species exhibited no visible injury.     

Tropospheric Ozone in Alpine Forest Sites: Air Quality Monitoring and Statistical Data Analysis

Plants represent one of the major sinks for tropospheric ozone that, at high concentrations, can affect plants' physiological activity with consequent serious damage. A research project has been promoted by the Lombardy Foundation for the Environment to investigate the effects of air pollution on forest ecosystems. The areas of study are located on the southern slopes of the Italian Alps in two valleys, only 10 km apart, selected because of their different plant injury: Val Gerola and Val Masino. Air quality (O₃, NO_x, SO_x, VOC) and meteorological parameters were monitored during four summer seasons (1994-97) using automatic sampling devices providing hourly mean values for each variable. Data analysis showed very different ambient ozone concentrations at the two sites, with average concentration values observed in the more damaged valley (Val Gerola) twice those measured at the other site. Multivariate data analyses have been used to interpret the observed differences in long-term O₃ exposure between the two sites and to identify possible underlying processes.