Micro-morphological and anatomical response of groundnut (Arachis hypogaea L.) cultivars to ground-level ozone (original) (raw)
Related papers
Physiological characteristics of tobacco cultivars with contrasting sensitivity to ozone
Environmental and Experimental Botany, 1997
Two cultivars of tobacco with contrasting sensitivity to ozone have similar photosynthesis at low light intensity, but at high light, photosynthesis of the sensitive cultivar Bel-W3 was lower than that of the resistant cultivar Havana. In contrast, the electron transport rate at photosynthesis saturated light intensity was higher in Bel-W3 than in Havana. This excess may require efficient mechanisms to dissipate energy and oxygen radicals. We found that the non-radiative dissipation was lower in Bel-W3 than in Havana and that the conversion between violaxanthin and antheraxanthin + zeaxanthin was not complete in the ozone sensitive cultivar. Violaxanthin may have been partly converted in ABA. The high content of ABA may have caused stomatal closure and explain why photosynthesis at high light was reduced in Bel-W3 in comparison to Havana. r-Carotene content was also lower in Bel-W3 than in Havana. A low rcarotene content coupled with an inefficient use of the xanthophyll mechanism may contribute to determine the ozone sensitivity of Bel-W3 leaves. © 1997 Published by Elsevier Science B.V.
The Journal of The University of Duhok
Tropospheric ozone is the most important atmospheric pollutant affecting agricultural crops due to its phytotoxicity. Wheat plant, as an important and dominant cereal crop has been found to be sensitive to elevated ozone levels leading to adverse effects on growth and productivity. The objective of this study is to assess the impact of the ambient air concentration and the future increase in tropospheric ozone concentration on some physiological and morphological traits of two wheat plant (Triticum durum) varieties, Semito and Creso. Open-top chamber (OTC) field experiments were conducted during two consecutive years 2016-2017 and 2017-2018 under environmental conditions of Kurdistan region of Iraq, accumulated exposure over threshold of 40 ppb (AOT40) was tested, the treatment were i) ambient air concentration (32-37) ppb, ii) 50 ppb and iii) 60 ppb. Elevated Ozone concentration show a significant negative effect on total chlorophyll content (SPAD), relative water content, leaf area, plant height and consequently reducing above ground biomass, while in the same time induced increase in proline content in flag leaves. The present study demonstrate that the elevated tropospheric Ozone concentration significantly affect a range of important physiological and morphological characteristics of both varieties of wheat plant (T. durum).
The open-top chamber method was employed to investigate the effects of ozone on 17 selected annual crops. Preparation of chambers and measurement of parameters in growth chambers were carried out according to recommended guidelines of the Agriculture Department, Sri Lanka. Responses of plants exposed to ambient air or ozone were detected by placing test plants in an artificially chambered area and controlling other environmental factors. Visible symptoms observed during the experiment can be categorized into seven symptom groups; stippling, yellowing, browning, reddening, malformation of leaves, stunting, elongation of stem and leaf abscission. Young plants of all species were more sensitive to ozone than mature plants. However, in all plants examined, mature leaves were first affected and further exposure to ozone resulted in leaf abscission followed by plant death.
Impact of Tropospheric Ozone on Crop Plants
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences, 2012
Tropospheric ozone (O 3 ) is the most important regional atmospheric pollutant causing risk to food production across the globe due to its phytotoxicity and prevalence over agricultural areas. Peak O 3 concentrations have declined in Europe and North America due to reductions in precursors during the last decades, however, emissions of O 3 precursors have increased in Asia. The current critical level of ozone is determined by the threshold for yield loss which is based on the seasonal sum of the external concentration above 40 ppb. In the present article, the impact of tropospheric O 3 on crop photosynthesis, defense mechanism, growth, reproductive processes and yield of crop plants have been documented. O 3 upon its entry into the leaf intercellular spaces rapidly forms reactive oxygen species and reacts with components of the leaf apoplast to initiate a complex set of responses that constitute variable countermeasures by antioxidative enzymes. Ozone affects photosynthetic process by influencing photosynthetic pigments, chlorophyll fluorescence kinetics and electron transport as well as carbon fixation in terms of decreased Rubisco activity and quantity. Translocation and allocation pattern of photosynthate also get influenced under O 3 , which affect reproductive processes and yield of crops. Plant species and cultivars exhibit a range of sensitivity to O 3 , which is identifiable in terms of biochemical, physiological, molecular and yield responses. Hence, understanding of cultivar sensitivity in context to O 3 would be helpful in development of potential O 3 biomarkers and O 3 tolerant variables.
Comparative ozone sensitivity of old and modern Greek cultivars of spring wheat
New Phytologist, 1990
Ten cultivars of spring wheat, hred and introduced in Greece hetween 1932 and 1980, were exposed to ozone (180/^g m"^) or to charcoal-filtered air (< 4/tg O3 m"^) for 21 d. Ozone sensitivity was assessed by recording the extent of visible injury, effects on mean relative growth rate {R) and changes in fast fluorescence kinetics. Ozone significantly (P<0-01) depressed the mean relative growth rate {R) and there were significant (P<0-01) differences in response hetween cultivars. Moreover, there was a highly significant (P < 0-002) negative relationship hetween the reduction in R and the year of introduction; the more modern the cultivar the greater its sensitivity to ozone. Ozone reduced root growth relative to the shoot, hut the effect varied with cultivar. Although all varieties developed typical visible symptoms of ozone damage, there was little relationship hetween the extent of this damage and effects on growth, or changes in fluorescence.
Differences in morpho-anatomical structure of ozone-sensitive and ozone-resistant tobacco cultivars
Acta Biologica Hungarica, 2010
Tropospheric ozone causes visible injuries in selected plants. Some plant species have been recognized as resistant and sensitive to ozone. Differences in the response to ozone of two kinds of plants are interesting because of practical implications. Resistant cultivars (without visible symptoms) will be more valuable for agriculture, forestry and horticulture. It is, however, necessary to find out the reason of the occurrence of the visible symptoms. The presented studies focused on selected morphological and anatomical differences between well-known ozone-sensitive (Bel W3) and -resistant (Bel B) cultivars of tobacco plants. Daily growth of the sensitive cultivar was higher than that of the resistant one. This tendency was also valid for the leaf growth which might have been the response of the sensitive cultivar to decreased photosynthetic leaf area (necrosis) caused by ozone. Morphological investigations revealed thinner upper epidermal cells in the sensitive cultivar. Moreover, a decrease of spongy mesophyll cell layers was observed. The obtained results suggest that it is the anatomical structure that may be partly responsible for ozone resistance -wider epidermal cells, more spongy mesophyll cell layers.
Tropospheric ozone is one of the most important constituent of photochemical smog. In Hungary, the bioindication of ozone has started in June 2007, using the ozone bioindicator clover clones (Trifolium repens NC-S and NC-R) and bean strains (Phaseolus vulgaris S156 and R123) according to the ICP Vegetation Protocol. Besides collecting ozone and meteorological data, ozone injuries, dry weight and number of flowers of clover plants, and dry weight and number of pods of bean clones were assessed. Stomatal conductance and chlorophyll fluorescence of experimental plants were also measured. The typical symptoms of ozone injury were observed on sensitive clones of both plant species, and the extent of symptoms proved to be directly proportional to the ozone pollution expressed as the cumulative daily AOT40 values. Besides the typical symptoms, number of flowers of clover clones could also be a useful indicator of tropospheric ozone load. In addition, the measured physiological parameters s...
Physiological and biochemical responses of cowpea (Vigna unguiculata (L.) Walp) to ozone
Songklanakarin Journal of Science and Technology
The aim of this research was to investigate physiological and biochemical responses of cowpea (Vigna unguiculata (L.) Walp) to ozone. There were two main factors of the experiment; level of ozone concentration at 40 and 70 ppb and plant ages at 7 and 21 days. Plants were grown in fumigation chambers in which inlet air was filtered by a charcoal filter. Additional ozone was given 8 hours/day for 7 days in ozone fumigating chambers. The ozone concentration in the control chambers was less than 10 ppb. The results showed the biomass of ozone-fumigated plants was significantly lower and leaf injury of ozone fumigated plants was significantly greater compared to the control group. The major visible-injury symptom appeared as chlorosis on the upper surface of the leaves. Antioxidant levels in the charcoal filtered (CF) plants and ozoned plants had significant differences because of their detoxification role in removing ozone and its derivatives. The ozone treatment of 7-day-old plants sho...
Impacts of increasing ozone on Indian plants
Increasing anthropogenic and biogenic emissions of precursor compounds have led to high tropospheric ozone concentrations in India particularly in Indo-Gangetic Plains, which is the most fertile and cultivated area of this rapidly developing country. Current ozone risk models, based on European and North American data, provide inaccurate estimations for crop losses in India. During the past decade, several ozone experiments have been conducted with the most important Indian crop species (e.g. wheat, rice, mustard, mung bean). Experimental work started in natural field conditions around Varanasi area in early 2000's, and the use of open top chambers and EDU (ethylene diurea) applications has now facilitated more advanced studies e.g. for intra-species sensitivity screening and mechanisms of tolerance. In this review, we identify and discuss the most important gaps of knowledge and future needs of action, e.g. more systematic nationwide monitoring for precursor and ozone formation over Indian region.
1998
A field study was conducted from May to October 1995 to assess ozone (O3) phytotoxicity in Catalonia (NE Spain) by determining a percentage value of leaf area injured by ozone on three tobacco cultivars, Bel-W3, Bel-C and Bel-B as bioindicators. Colorimetric parameters were also determined in an effort to have an objective assessment of ozone injury. The study was conducted simultaneously on eight sites where ozone levels and several meteorological parameters were continuosly monitored. Two sets of plants were used at each site. The first one was composed of six plants of each cultivar which were changed every two weeks while the second one involved two plants of each cultivar which were kept in the plots throughout the whole experimental period. Open Top Chambers were also used to test the response of the three cultivars to ozone under controlled conditions. The ozone levels correlated well with ozone injury on the Bel-W3 cultivar but not as well on the other two cultivars. The ozone levels did not fully account for all the observed injury. The response of tobacco plants to ozone concentrations and therefore its biomonitoring capacity depended also on different environmental conditions linked to stomatal behaviour such as temperature, humidity, wind or altitude. These environmental conditions had some effects on the intensity of Ozone injury. Ozone concentrations accumulated over a threshold of 60 ppb (AOT60) when VPD was below 1 KPa. Correlated well with the ozone injury and best explained the intensity tobacco injury symptoms. For large plants growing throughout the whole period of study, Bel-C was the best indicator cultivar for AOT60 over the 3 days prior to the last ozone injury assessment. The colorimetric parameters were indicators of seasonal changes but they were not good ozone damage indicators. It is concluded that tobacco cultivars were good bioindicators but meteorological and other environmental factors need to be considered in there use as biomonitors.