Effect of thioglycerol capping on morphology and structure of chemically deposited CdS:NaF,La films

This paper reports the  effect of thioglycerol as capping agent for synthesis of lanthanum (La) doped nanocrystalline CdS semiconducting films on the glass substrate by means of chemical bath deposition (CBD), with Cd(CH3COO)2 as Cadmium (Cd) ion source, and (NH2)2CS as sulphur (S) ion source. Long, rod like structures is observed in SEM micrographs of the films. XRD studies show the existence of both hexagonal and cubic phases. Increase in FWHM is observed for smaller particle due to nanocrystalline effect. UV-VIS absorption studies show shift of absorption edge towards lower wavelength side.&nbsp

Implications of Foliar Particulate Matter Deposition on the Physiology and Nutrient Allocation of Dominant Perennial Species of the Indo-Gangetic Plains

The ramifications of different concentrations of foliar particulate matter on the physiology, nutrient stoichiometry, allocation pattern, and their corresponding re-translocation rates were investigated for evergreen (Mangifera indica and Psidium guajava), semi-evergreen (Ficus religiosa and Azadirachta indica), and deciduous (Dalbergia sissoo) tree species in a simulation experiment over an exposure period of 2 years. Physiological parameters (Pn, gs, Ci, E, and WUE), nutrient stoichiometry (C: N) in different plant parts, and their allocation pattern for five macro- (C, N, K, Mg, Ca) and five (Zn, Ni, Mn, Cu, Fe) micro-elements at two different concentrations of particulate matter (ambient and elevated) with respect to control (no particulate load) were assessed. Significant differences in nutrient concentrations and their re-translocation rates were observed between the treatments in evergreen species compared to deciduous species. The photosynthetic rate significantly declined with an increase in foliar deposition of particulate matter. Higher variations in C, N, K, Mg, and Zn levels were found compared to other elements under particulate matter stress and the ratio of C/N showed a slight decline in mature leaves except in deciduous tree species. The nutrient stoichiometry revealed that the deciduous species were more tolerant whereas the re-translocation efficiency was maximum for the semi-evergreen tree species. The nutrient allocation was found greater in foliage compared to branch in evergreen and was opposite in semi-evergreen and deciduous tree species. The element re-translocation rate indicated an inconsistent behavior in nutrient recycling under the particulate matter load depending upon the tree species. The study entrenched a critical change in nutrient re-translocation and allocation pattern under the particulate stress in different parts of the tree, suggesting a novel approach for screening the tree species for sustainable plantation and planning of urban areas

Role of gamma radiation in changing phytotoxic effect of elevated level of ozone in Trifolium alexandrinum L. (Clover)

AbstractThe present study was conducted on clover (Trifolium alexandrinum L. cv Wardan), to investigate the effect of ambient and elevated (ambient +10 ppb O3) ozone (O3) on plants grown in open top chambers (OTCs) germinated from gamma (γ) irradiated seeds. Dry seeds were subjected to irradiation with 0, 5, 10 and 20 krad doses of γ rays from 60Co source. Dose dependent differential responses were observed on growth and biomass, photosynthetic pigments, metabolites, antioxidative defense system of plant. Growth parameters and biomass of plants were severely affected under elevated O3 with increasing radiation doses, except, 5 krad which showed a reverse trend of response. Photosynthetic pigments and total soluble proteins were also reduced with higher dose of γ radiation and elevated O3. Reactive oxygen species formation and membrane damage increased significantly to different extents. Plants grown from seeds irradiated with low dose (5 krad) of γ irradiation depicted more induction of antioxidants (enzymatic and non–enzymatic) than higher doses suggesting their high ameliorative capability against elevated O3. Principal component analysis has also confirmed that plants grown from 5 krad γ irradiated seeds performed better against O3 depicting reduction in negative effect against elevated O3. The experimental findings evidently showed that 5 krad γ radiations altered the O3 induced stress and thus minimized the loss in biomass of the test plant

Assessment of the Reverberations Caused by Predominant Air Pollutants on Urban Vegetation: A Multi-Site Study in Varanasi Located in Indo-Gangetic Plains

Plant responses to air pollution have been extensively studied in urban environments. Nevertheless, detailed and holistic studies assessing their retaliation to air contaminants are still limited. The present study evaluates the effect of criteria pollutants (SO2, NO2, PM10 and O3) on the overall biochemistry and resource allocation strategy of plants in order to categorize the dominant roadside species (Mangifera indica, Psidium guajava, Ficus religiosa, Azadirachta indica, Dalbergia sissoo, Cascabela thevetia and Bougainvillea spectabilis) of the Indo-Gangetic Plains (IGP), with different morphologies and habits, into species that are tolerant and sensitive to the prevailing air pollutants. This study was performed at three different land-use sites (industrial, commercial and reference) in Varanasi for two seasons (summer and winter). It was inferred that NO2 and PM10 consistently violated the air quality standards at all the sites. The fifteen assessed parameters reflected significant variations depending upon the site, season and plant species whereupon the enzymatic antioxidants (superoxide dismutase and catalase) and resource utilization parameters (leaf area and leaf dry matter content) were remarkably affected. Based on the studied parameters, it was entrenched that deciduous tree species with compound leaves (D. sissoo > A. indica) were identified as the less sensitive, followed by a shrub (C. thevetia > B. spectabilis), while evergreen species with simple leaves were the most sensitive. It was also substantiated that the morphology of the foliage contributed more toward the differential response of the plants to air pollutants than its habit

Diurnal Variations in Physiological Characteristics, Photoassimilates, and Total Ascorbate in Early and Late Sown Indian Wheat Cultivars under Exposure to Elevated Ozone

Rising tropospheric ozone (O3) in the atmosphere is detrimental to crop’s productivity and is one of the reasons for a warmer climate. The present study describes diurnal changes in gaseous exchange, chlorophyll fluorescence, ascorbic acid, and photoassimilate parameters in flag leaves of four Indian wheat (Triticum aestivum L.) cultivars (two early sown and two late sown cultivars) under ambient and elevated O3 treatments, using the open-top chambers (OTCs). Results showed that the diurnal pattern of photosynthetic rate (Ps), sucrose, and ascorbic acid content varied according to changes in photosynthetically active radiation (PAR) and O3 concentrations during the daytime and were maximum between 10:00 to 12:00. The present study suggested that elevated O3 caused more negative effects on photosystem II in early sown compared to late sown cultivars. The greater loss of photosynthesis led to lower production of photoassimilates in early sown cultivars, which utilized more assimilates in ascorbic acid formation for detoxification of ROS formed due to elevated O3. This work will also help to identify the robustness of physiological machinery in different wheat cultivars under elevated levels of O3, and may be used for selection of suitable cultivars during future breeding programs

Assessment of Ozone Sensitivity in Three Wheat Cultivars Using Ethylenediurea

Three wheat (Triticum aestivum L.) cultivars [HD 2987 (ozone (O3) sensitive), PBW 502 (intermediately sensitive) and Kharchiya 65 (O3 tolerant)] with known sensitivity to O3 were re-evaluated using ethylenediurea (EDU; 400 ppm) to ascertain the use of EDU in determiningO3 sensitivity under highly O3-polluted tropical environments. EDU treatment helped in improving the growth, biomass, photosynthetic pigments and the antioxidative defense system of all the wheat cultivars. Under EDU treatment, PBW 502 retained more biomass, while HD 2987 showed better performance and ultimately the greatest increment in yield. Cultivar Kharchiya 65 also showed a positive response to EDU as manifested with an increase in pigment contents, total biomass and enzymatic antioxidants; however, this increment was comparatively lower compared to the other two cultivars. The results indicated that EDU did not have many physiological effects on cultivars but helped in counteracting O3 primarily by scavenging reactive oxygen species and enhancing the antioxidative defense system where superoxide dismutase emerged as the major responsive biochemical parameter against ambient O3. The observed results clearly indicated that differential O3 sensitivity in three wheat cultivars established by the previous study is in accordance with the present study using EDU as a sensitivity tool, which is an easy and efficient technology in comparison to chamber and Free-Air Carbon dioxide Enrichment (FACE) experiments although its mechanistic understanding needs to be further validated

Secluding the vegetation of India in retaliation to tropospheric ozone: a mechanistic approach

Abstract Rapid urban development and population outbursts in India have led to a tremendous increase in pollutant emissions and their transboundary dispersion. Hence, the increase in tropospheric ozone (O3) formation is further amplified depending on the meteorology of the area. This review attempts to compile the studies reporting tropospheric O3-induced loss of yield and biomass in the vegetation of the Indian sub-continent from 2012 to 2023, with a mechanistic approach. The response of vegetation (agricultural, horticultural, perennial, medicinal and grassland) to O3 have been collated and their order of sensitivity has been established. The vegetation displayed two significant strategies to cope with the O3 induced stress- stomatal flux regulation and shifting the photoassimilates towards either defense or reproduction (trade-off), which decides the plant's ability to respond towards O3. Considering the varying responses of plants, it was observed that plants that adopted both stomatal regulation and trade-off strategies to endure the stress were least sensitive to O3 than those focusing on one of them