Influence of soil substrate and ozone plus acid mist on the pigment content and composition of needles from young Norway spruce trees

Photosynthetic rate and chlorophyll fluorescence of barley exposed to simulated acid rain

Acid rain is considered one of the most serious plant abiotic stresses. Photosynthesis is the basis of crop growth and development. The effect of acid rain on barley photosynthesis remains unclear. A glasshouse experiment was conducted, and the photosynthetic rate, chlorophyll (Chl) fluorescence, and pigment content of barley were measured in simulated acid rain (SAR) under pH 6.5, 5.5, 4.5, and 3.5. The results showed that net photosynthetic rate, maximal photosynthetic rate, and light saturation point decreased and the light compensation point, and dark respiration rate increased with increasing acidity. The results suggested that photosynthesis in barley plants was inhibited by SAR stress. The Chl content and stomatal conductance declined in parallel with the reduced net photosynthetic rate when barley plants were under SAR stress conditions. This indicated that non-stomatal factors may contribute to reduced photosynthesis under acid rain stress. Acid rain had greater effects on the photosynthesis of the acid rain-sensitive plant Zhepi 33 than on non-sensitive Kunlun 12. A significant difference in parameters such as the maximal fluorescence, variable fluorescence, and active PSII reaction centers was found among the SAR treatments and may be used to evaluate the sensitivity of plants to acid rain stress. The visualization model showed that the photosynthetic reaction centers were inactivated in acid rain stressed barley plants. These findings are valuable for the evaluation of the plant sensitivity to acid rain stress and may be used for the detection and monitoring of acid rain effects on plants in the future.

Investigation of metal concentrations in roadside soils and plants in urban areas of Amritsar, Punjab, India, under different traffic densities

Vehicular emissions containing traces of different heavy metals are known to cause significant contamination of roadside soils and plants. The present study was conducted to investigate the heavy metal concentrations in roadside soil and plant samples (Alstonia scholaris, Nerium oleander, Tabernaemontana divaricata, and Thevetia peruviana) collected from urban areas of Amritsar city of Punjab, India, under different traffic densities. The soil and plant samples were collected in pre- and post-monsoon seasons from seven roadside sites under varying levels of traffic density and analyzed for four heavy metals (Cd, Cu, Pb, and Zn). In addition to that, total protein and carotenoid contents in plant samples were also determined. pH and electrical conductivity analysis of roadside soil samples revealed slight to strongly alkaline and non-saline nature of soil. Significant reduction in contents of total proteins and carotenoids was observed in plants collected from sites with moderate to high traffic density. The trend of heavy metal contents in plants and their corresponding soil samples was observed to be Zn > Cu > Pb > Cd for both the seasons. Index of geo-accumulation indicated moderate contamination of soil with metals analyzed, while bio-accumulation factor (BAF) showed both absorption and accumulation of metals in plants under study. The study revealed significant contamination of roadside soil and plants of Amritsar city which was linked to vehicular emissions posing potential risk to human health.

Morphophysiological variation and metal concentration in the thallus of Parmotrema tinctorum (Despr. ex Nyl.) Hale between urban and forest areas in the subtropical region of Brazil

Anthropic activities such as the emission of pollutants resulting from industrial and agropastoral activities promote several changes in urban and forest areas. Lichens are organisms that are used in air quality evaluations due to their sensitivity to these changes. The aim of this study is to analyze the presence of morphophysiological damages and the metal concentration in samples of the lichen Parmotrema tinctorum, in urban and forest areas, checking for possible parameter variations between these areas, in the different matrices and seasons in the Southern region of Brazil. Six areas were selected (urban and forest), assigned to the rural/urban and urban/industrial matrices belonging to the watershed of the Rio dos Sinos, Brazil. The following parameters were analyzed: Index of photobiont vitality (IPV), photosynthetic pigments (chlorophyll, carotene, and pheophytin) and metals (Cu, Cr, Zn, Pb, and Ni) in the thallus of the lichen. The data were analyzed by an ANOVA one way, Pearson correlation test, and principal component analysis (PCA). Variations in the morphophysiological parameters were recorded in all the areas revealing significant differences. The lowest IPV values and highest concentration of metals were recorded in the urban environment, while low chlorophyll levels were found in the forest areas. The PCA showed a distinction between the areas and the season. The level of urbanization, vehicle traffic, and the weather conditions might have influenced the results. The use of P. tinctorum, the index of photobiont vitality and chlorophyll and pheophytin content, has proved to be an efficient tool to diagnose the air quality in the areas analyzed, allowing its use as a model in air monitoring studies, both in urban and forest areas, as well as in distinct matrices in the subtropical region.

Impacts of particulate matter pollution on plants: Implications for environmental biomonitoring

Air pollution is one of the serious problems world is facing in recent Anthropocene era of rapid industrialization and urbanization. Specifically particulate matter (PM) pollution represents a threat to both the environment and human health. The changed ambient environment due to the PM pollutant in urban areas has exerted a profound influence on the morphological, biochemical and physiological status of plants and its responses. Taking into account the characteristics of the vegetation (wide distribution, greater contact area etc.) it turns out to be an effective indicator of the overall impact of PM pollution and harmful effects of PM pollution on vegetation have been reviewed in the present paper, covering an extensive span of 1960 to March 2016. The present review critically describes the impact of PM pollution and its constituents (e.g. heavy metals and poly-aromatic hydrocarbons) on the morphological attributes such as leaf area, leaf number, stomata structure, flowering, growth and reproduction as well as biochemical parameters such as pigment content, enzymes, ascorbic acid, protein, sugar and physiological aspect such as pH and Relative water content. Further, the paper provides a brief overview on the impact of PM on biodiversity and climate change. Moreover, the review emphasizes the genotoxic impacts of PM on plants. Finally, on the basis of such studies tolerant plants as potent biomonitors with high Air Pollution Tolerance Index (APTI) and Air Pollution Index (API) can be screened and may be recommended for green belt development.

Assessment of the variability in response of radish and brinjal at biochemical and physiological levels under similar ozone exposure conditions

The present investigation was done to evaluate the effects of ambient air pollutants on physiological and biochemical characteristics of radish (Raphnus sativa L. var. Pusa Reshmi) and brinjal (Solanum melongena L. var. Pusa hybrid-6) plants grown in open-top chambers with filtered (FCs) and non-filtered (NFCs) treatments at a suburban site in Varanasi, India. Eight hourly mean concentrations of 11.8, 20.8, and 40.8 ppb for SO2, NO2, and O3, respectively, were recorded. O3 was the most significant pollutant affecting the plant performance. Photosynthetic rate and stomatal conductance declined in both the test plants in NFCs as compared to FCs. Lipid peroxidation was higher in NFCs, but the increase was more in radish compared to brinjal. The constitutive levels of the antioxidants as well as their increments upon O3 exposure were of higher magnitude in brinjal as compared to radish. Reduction in Fv/Fm ratio of the plants in NFCs was a regulatory mechanism to cope with the inefficiency of Calvin cycle. The data indicate that O3 triggered the protective mechanisms in plants which resulted in increments in enzymatic and non-enzymatic antioxidants of O3-exposed plants. The variability of the magnitude of responses in radish and brinjal due to O3 stress suggests that radish is more susceptible to ambient O3 injury compared to brinjal.

Biochemical responses in tree foliage exposed to coal-fired power plant emission in seasonally dry tropical environment

A biomonitoring study was conducted to investigate the responses of plants exposed to power plant emission in a dry tropical environment. For this purpose, five sampling sites were selected in the prevailing wind direction (NE) at different distance to thermal power plant (TPP) within 8.0 km range and a reference site was selected in eastern direction at a distance of 22.0 km. The two most common tree species, Ficus benghalensis L. (Evergreen tree) and Dalbergia sisso Roxb. (deciduous tree) were selected as test plants. Ambient sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), suspended particulate matter (SPM), respirable suspended particulate matter (RSPM), dust-fall rate (DFR) and plant responses such as leaf pigments (chlorophyll a, chlorophyll b and carotenoids), ascorbic acid, sugar and sulphate-sulphur (SO4(2-)-S) contents were measured. Ambient SO(2), NO(2), SPM, RSPM and DFR showed significant spatial and temporal variation at different sites. Considerable reduction in pigment (chlorophyll a, chlorophyll b and carotenoids) and sugar contents were observed at sites receiving higher pollution load. Ascorbic acid exhibited significant positive correlation with pollution load. Accumulation of SO4(2-)-S in leaf tissue showed significant positive correlation with ambient SO(2) concentration at all the sites. At the same time, SO4(2-)-S showed significant negative correlation with pigment and sugar content. D. sisso Roxb. tree was found to be more sensitive as compared to F. benghalensis L. tree.

Biochemical and ultrastructural changes in plant foliage exposed to auto-pollution

Auto-pollution is the by-product of our mechanized mobility, which adversely affects both plant and human life. However, plants growing in the urban locations provide a great respite to us from the brunt of auto-pollution by absorbing the pollutants at their foliar surface. Foliar surface configuration and biochemical changes in two selected plant species, namely Ficus religiosa L. and Thevetia nerifolia L., growing at IT crossing (highly polluted sites), Picup bhawan crossing (moderately polluted site) and Kukrail Forest Picnic Spot (Low polluted site) were investigated. It was observed that auto-exhaust pollution showed marked alterations in photosynthetic pigments, protein and cysteine contents and also in leaf area and foliar surface architecture of plants growing at HP site as compared to LP site. The changes in the foliar configuration reveal that these plants can be used as biomarkers of auto-pollution.

Response to ozone in two lettuce varieties on chlorophyll a fluorescence, photosynthetic pigments and lipid peroxidation

The effect of different O3 concentrations on two lettuce (Lactuca sativa L.) varieties (Valladolid and Morella) was investigated through chlorophyll (Chl) a fluorescence parameters, photosynthetic pigments (Chl a, b and total carotenoid), lipid peroxidation and crop yield. Ozone fumigation caused: a decrease in maximum quantum yield of photosystem II (PSII) photochemistry (Fv/Fm) in mature leaves, a reduction in the non-cyclic electron flow (phiPSII) and a lower capacity to reoxidize the QA pool (qP). These reductions were significant in the Valladolid var. but not in the Morella var. A significant decrease in Chl a, b and in the total carotenoids was observed in the Valladolid var. but not in the Morella var. mainly under O3 fumigation conditions. We observed that the NPQ parameter did not increase in parallel to the qP reduction seen in the Valladolid var. O3 fumigation with respect to air charcoal filtered air conditions. This fact could be associated with a lower capacity for dissipation of non-radiative excess energy and it may be closely correlated with significant decreases in photosynthetic pigment concentration. A decrease in NPQ from air ozone-free to ozone fumigation in the Morella var. can be explained by the need to maintain the photochemical quenching under O3 stress. It may also be associated with a slight increase in photosynthetic pigments. The differences between the two varieties may indicate that the Valladolid var. is more susceptible to O3 damage.

Changes in pigment concentration and composition in Norway spruce induced by long-term exposure to low levels of ozone

Rametes of Norway spruce were fumigated with 30 ppb (nl litre(-1)) ozone above ambient level for 4 years in open-top chambers. They were grown under different light conditions, because some of the chambers received approximately 10% less light than the others. Samples from three age classes were analyzed for nitrogen and pigments using HPLC. It could be demonstrated that the ozone treatment reduced the concentration of chlorophyll (a) and (b), alpha- and beta-carotene, but increased the concentration of antheraxanthin. A significant decrease was found for the violaxanthin/antheraxanthin ratio following the ozone treatment. The concentration of all the pigments and of nitrogen were significantly related to the age classes, and a similar relationship was found for the light levels, except for antheraxanthin and total carotenoids. The ratio of chlorophyll a/b was only significantly related to the age classes.

Exposure of Norway spruce to ozone increases the sensitivity of current year needles to photoinhibition and desiccation

Physiological effects of ozone exposure over three consecutive growing seasons on current year needles of Norway spruce were studied in open-top chambers, during daily Fumigation cycles in the summer, and after the termination of ozone fumigation in autumn 1990. The trees were exposed to two levels of ozone: charcoal filtered air and non-filtered air to which 30 nl I^-1 of ozone was added in three consecutive years from 1988 to 1990, daily from May to September (8 hours a day). Photosynthesis, stomatal conductance, transpiration and chlorophyll fluorescence were studied on selected days. Significant decreases in net photosynthesis and chlorophyll fluorescence (F_N /F_M ) were found during periods with co-occurrence of high ozone concentrations And high light intensities, indicating interactions between effects of ozone and photoinhibition. After termination of fumigation enhanced rates of photosynthesis were seen in the trees which had been exposed to ozone. A significant decrease in F_N /F_M was found for twigs from ozone treated trees when exposed to severe desiccation.

Investigations on the photosynthetic system of spruce affected by forest decline and ozone fumigation in closed chambers

Investigations using chlorophyll fluorescence induction kinetics provide the parameters Rfd, L, and Ap to characterize different specifications of the photosynthetic system (PS). The application of ozone, with concentrations between 100 microg m(-3) and 2000 microg m(-3) to spruce in closed chambers yields a reduction of Rfd between 6% and 23% for the current year's needles, which indicates a reduced potential photosynthetic capacity. Further measurements on the current year's needles of spruce of the damage classes S0/S1, S2 and S3 show also a reduction of Rfd of between 7% and 14% in 2 successive years. In addition, the parameter L increases for damaged trees by between 11% and 49%, indicating a change of the chlorophyll content and of the internal energy distribution between PSI and PSII. As no effect of L can be observed with ozone fumigation, it is concluded that the change of some specifications of the PS can be simulated well by ozone fumigation (e.g. Rfd) while other specifications cannot (e.g. L).