Ozone Effects on Fruit Productivity and Photosynthetic Response of Two Tomato Cultivars in Relation to Stomatal Fluxes (original) (raw)
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Adverse effects of ambient ozone on watermelon yield and physiology at a rural site in Eastern Spain
New Phytologist, 1999
The study reported was conducted to establish the impacts of photochemical oxidants (primarily ambient ozone, O $ ) on the yield of watermelon (Citrullus lanatus) at a site on the east coast of Spain. Fruit yield and quality were monitored in plots established in a commercial watermelon field exposed, in open-top chambers (OTCs), to nonfiltered air (NFA ; near-ambient levels of ozone) or charcoal-filtered air (decreased levels of photochemical oxidants including O $ ; CFA), or to ambient air (AA), during the 1988 and 1989 growing seasons. Ambient levels of O $ were found to exceed present UN-ECE (United Nations Economic Commission for Europe ; Convention on Long-Range Transboundary Air Pollution) critical level guidelines for the protection of crop yield by approx. twofold in 1988 and by approx. fivefold in 1989. Plants exposed to NFA and AA developed visible O $ injury on the upper surface of sun-exposed older leaves, and fruit yield (annual marketable fruit weight and number) was found to be depressed in OTCs ventilated with NFA in comparison with those receiving CFA. Consistent with inter-annual variations in O $ exposure, greater yield losses were experienced in 1989 (39%) than in 1988 (19%), an effect mediated predominantly by a decline in fruit number rather than average fruit weight. Exposure to ambient levels of ozone also slightly decreased fruit quality (4-8% decline in soluble solids content). Leaf gas exchange measurements made in the field in 1988 revealed effects of O $ on fruit yield and quality to be associated with a decline in the net CO # assimilation rate per unit leaf area under light saturation (A sat ) and stomatal conductance to water vapour (g s ), and enhanced rates of dark respiration. A\c i curves (where A is the net CO # assimilation rate per unit leaf area and c i is the mole fraction of CO # in the leaf intercellular air space) constructed for plants grown in laboratory-based closed chambers, and exposed to an accumulated O $ exposure similar to that experienced by plants in the field, suggested that the likely cause of the decline in photosynthetic capacity was (1) a decrease in the amount and\or activity of Rubisco and (2) an impaired capacity for regeneration of ribulose 1,5bisphosphate, which was not mediated through changes in the photochemical efficiency of photosystem II (F v \F m , where F v is variable chlorophyll a fluorescence and F m is maximum chlorophyll a fluorescence). No shift in the relative stomatal limitation to photosynthesis was observed under the influence of O $ , suggesting that the decline in g s induced by the pollutant in both field and laboratory was the result, and not the cause, of the decrease in A sat . Ozone exposure also caused a decrease in C isotope discrimination (approx. 0.5=), a shift that revealed a departure from predicted theory based on supporting leaf gas exchange measurements. The study demonstrates that ambient levels of photochemical oxidants on the Spanish Mediterranean coast are high enough to adversely influence the yield and physiology of an economically important crop grown in the region, and the magnitude of the effects was
Photosynthetica, 2014
The crop sensitivity to ozone (O 3 ) is affected by the timing of the O 3 exposure, by the O 3 concentration, and by the crop age. To determine the physiological response to the acute ozone stress, tomato plants were exposed to O 3 at two growth stages. In Experiment I (Exp. I), O 3 (500 µg m -3 ) was applied to 30-d-old plants (PL30). In Experiment II (Exp. II), three O 3 concentrations (200, 350, and 500 µg m -3 ) were applied to 51-d-old plants (PL51). The time of the treatment was 4 h (7:30 -11:30 h). Photosynthesis and chlorophyll fluorescence measurements were done 4 times (before the exposure; 20 min, 20 h, and 2-3 weeks after the end of the treatment) using a LI-COR 6400 photosynthesis meter. The stomatal pore area and stomatal conductance were reduced as the O 3 concentration increased. Ozone induced the decrease in the photosynthetic parameters of tomato regardless of the plant age. Both the photosystem (PS) II operating efficiency and the maximum quantum efficiency of PSII photochemistry declined under the ozone stress suggesting that the PSII activity was inhibited by O 3 . The impaired PSII contributed to the reduced photosynthetic rate. The greater decline of photosynthetic parameters was found in the PL30 compared with the PL51. It proved the age-dependent ozone sensitivity of tomato, where the younger plants were more vulnerable. Ozone caused the degradation of photosynthetic apparatus, which affected the photosynthesis of tomato plants depending on the growth stage and the O 3 concentration. transport rate; F0 -minimal fluorescence of the dark-adapted leaf; F0' -minimal fluorescence of the light-adapted leaf; Fm -maximal fluorescence of the dark-adapted leaf; Fm' -maximal fluorescence of the light-adapted leaf; Fs -steady-state fluorescence; gs -stomatal conductance; Jmax -the maximum rate of carboxylation limited by electron transport rate for RuBP generation; NADPH -nicotinamide adenine dinucleotide phosphate; O200 -ozone treatment of 200 μg m -3 ; O350 -ozone treatment of 350 μg m -3 ; O500 -ozone treatment of 500 μg m -3 ; Pmax -light-saturated photosynthetic rate; PN -net photosynthetic rate; PL30 -30-d-old plants; PL51 -51-d-old plants; PPFD -photosynthetic photon flux density; PSphotosystem; qP -photochemical quenching coefficient; RD -dark-respiration rate; Rubisco -ribulose-1,5-bisphosphate carboxylase/ oxygenase; tb -before O3 treatment; t20m -20 min after O3 treatment; t20h -20 h after O3 treatment; t3w -2-3 weeks after O3 treatment; TPU -triose phosphate use; Vcmax -maximum carboxylation velocity of Rubisco; α -initial slope of the light curve at low PPFD; Θ -curve convexity; ΦCO2 -quantum yield of carboxylation rate; ФPSII -effective quantum yield of photosystem II photochemistry. Acknowledgements: The authors thank the Scholarship Foundation (French Embassy -Thailand International Cooperation Agency -Thailand Research Fund) for financial support.
Setting ozone critical levels for protecting horticultural Mediterranean crops: Case study of tomato
Environmental Pollution, 2014
Seven experiments carried out in Italy and Spain have been used to parameterising a stomatal conductance model and establishing exposuree and doseeresponse relationships for yield and quality of tomato with the main goal of setting O 3 critical levels (CLe). CLe with confidence intervals, between brackets, were set at an accumulated hourly O 3 exposure over 40 nl l À1 , AOT40 ¼ 8.4 (1.2, 15.6) ppm h and a phytotoxic ozone dose above a threshold of 6 nmol m À2 s À1 , POD6 ¼ 2.7 (0.8, 4.6) mmol m À2 for yield and AOT40 ¼ 18.7 (8.5, 28.8) ppm h and POD6 ¼ 4.1 (2.0, 6.2) mmol m À2 for quality, both indices performing equally well. CLe confidence intervals provide information on the quality of the dataset and should be included in future calculations of O 3 CLe for improving current methodologies.
Vegetable Crops Research Bulletin, 2010
Effect of ozone on three different growth phase of tomato (Lycopersicon esculentum cv. Pusa ruby) crop namely, Early Vegetative Phase (EVP), 30 days old plants; Late Vegetative Phase (LVP), 45 days old plants; and Fruiting Phase (FP), 60 days old plants were exposed to ozone concentrations (75 ppb and 150 ppb) in closed top dynamic chambers for 12 days period. Ozone exposed tomato plants of all the three growth stages exhibited visible injury symptoms as chlorotic spots in variable intensity. Effect of ozone exposure on tomato crop plants was examined with respect to isoprene emission, growth and yield parameters. Enhancement in isoprene emission was observed from ozone exposed tomato plants as compared to unexposed plants. In exposed plants of early vegetative phase isoprene emission was 127% and 187% higher immediately after (within 1 hr) 75 ppb and 150 ppb ozone exposure respectively as compared to unexposed plants. Significant (p≤0.001) reduction in ozone exposed plants shoot length (2 to 10.5%), chlorophyll content (7 to 39%), carotenoids contents (5 to 42%), shoot biomass (upto 44%) and root biomass (8 to 65%) were observed as compared to unexposed plant. It was found that ozone exposure was more detrimental to LVP in comparison to FP and EVP. The results of the study also showed that 150 ppb of ozone exerted more harmful effects on the growth of different growth phases of tomato plants than 75 ppb ozone.
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.
Physiological and Nutritional Responses to Ozone Application in Tomato Seedling Plants
Agriculture
Research on environmentally friendly techniques for the agroindustry is growing constantly. In this sense, the supply of ozone (O3) has been taken into consideration, especially for disinfection because of its high oxidizing power. However, there is not enough information about the application of dissolved O3 via fertigation in crops. For that reason, in this study, two trials were carried out simultaneously to determine the consequences of O3 application on plant growth and quality of tomato plants. The first trial aimed to assess the effects on tomato fertigated with the nutrient solution and the application of O3. The second trial was performed to establish the ideal O3 supply rate for tomato plants. In both experiments, we measured the biometric, physiological, and nutritional parameters of the tomato plant. The results obtained showed that the application of O3 treatment resulted in the highest overall dry weight gain, whereas O3 application decreased leaf proline and total sol...
Impact of atmospheric ozone-enrichment on quality-related attributes of tomato fruit
Postharvest Biology and Technology, 2007
Tomato fruit (Lycopersicon esculentum L. cv. Carousel) were exposed to ozone concentrations ranging between 0.005 (controls) and 1.0 mol mol −1 at 13 • C and 95% RH. Quality-related attributes and organoleptic characteristics were examined during and following ozone treatment. Levels of soluble sugars (glucose, fructose) were maintained in ozone-treated fruit following transfer to 'clean air', and a transient increase in -carotene, lutein and lycopene content was observed in ozone-treated fruit, though the effect was not sustained. Ozone-enrichment also maintained fruit firmness in comparison with fruit stored in 'clean air'. Ozone-treatment did not affect fruit weight loss, antioxidant status, CO 2 /H 2 O exchange, ethylene production or organic acid, vitamin C (pulp and seed) and total phenolic content. Panel trials (employing choice tests, based on both appearance and sensory evaluation) revealed an overwhelming preference for fruit subject to low-level ozone-enrichment (0.15 mol mol −1 ), with the effect persisting following packaging.
Environmental and Experimental Botany, 2005
In a 2-year study, fruiting plants of strawberry (Fragaria × ananassa Duch.) cv. 'Korona' and 'Elsanta' were exposed for 2 months to 78 ppb ozone on average or filtered air without ozone in controlled environment chambers. Plant growth, photosynthesis, carbohydrate accumulation, and macronutrient concentrations were investigated in order to demonstrate cultivar-specific differences in the ozone sensitivity of 'Korona' and 'Elsanta' on the whole plant level. Moreover, the hypothesis was tested whether properties of the root system in strawberry were involved in ozone tolerance, for example, the roots' ability to store or make available carbohydrates and their capacity to secure plants' supply with nitrogen during a stress situation. In strawberry, ozone reduced leaf area by reducing leaf number. Moreover, specific leaf area (SLA) and relative leaf water content were reduced. Net photosynthesis was only slightly impaired, but activity of Rubisco and chlorophyll content in older leaves of cv. 'Elsanta' were significantly reduced. The most important, indirect impairment of photosynthesis was the reduction of plants' total leaf area, which resulted in a decrease in plant biomass. The reduction of root biomass, the root/shoot ratio, and also the distribution of carbohydrates indicated a partitioning priority of the shoot at expense of the root system. Cultivar 'Elsanta' was characterized by significantly lower carbohydrate levels in ozone-exposed leaves, whereas levels remained fairly stable in 'Korona' leaves. In addition, nitrogen concentrations in leaves and roots decreased significantly in 'Elsanta', not in 'Korona'. The reduced nitrogen concentration in leaves may be related with the more distinct reduction in Rubisco activity and chlorophyll content in older leaves of 'Elsanta'.
Environmental Pollution, 1993
Two cultivars of watermelon (Citrullus lanatus) and muskmelon (Cucumis melo), which are widely grown in Spain, were exposed to ozone (70 nl litre -l, 6 h d 1) for 21 days. Ozone sensitivity was assessed by recording the extent of visible injury, changes in fast-fluorescence kinetics, the relative-growth rate (R) of root (RR) and shoot (~s), and effects on the number of flowers produced per plant. Leaf gas exchange was measured in order to provide some indication of the factors underlying differential response to ozone. After 9-10 days of fumigation, all the cultivars developed typical visible symptoms of ozone injury on the older leaves. However, significant (P < 0.05) changes in fast-fluorescence kinetics were detected prior to the development of visible foliar injury, indicating that detectable effects of ozone on primary photochemical processes supersede the appearance of visible symptoms. In both muskmelon and watermelon, there was a marked reduction in the rate of C02 assimilation as a result of exposure to ozone, and this was accompanied by a parallel decrease in stomatal conductance. Mean plant-relative-growth rate (R) was markedly (P < 0.01) suppressed by ozone in the two cultivars of watermelon, but there were no significant effects on R in muskmelon. Ozone reduced root growth relative to the shoot in three out off our cultivars---an effect that may be of considerable ecological significance. Moreover, exposure to ozone reduced flower production in both muskmelon and watermelon, which indicated effects on yield There was no correlation between a variety of methods used to assess ozone sensitivity and visible injury, and reasons for this are discussed. This observation draws clear attention to the dangers in ranking plants for ozone sensitivity purely on the basis of visible symptoms. It is concluded from this study that ozone-insensitive genotypes should be identified and considered for planting in the major areas of melon production concentrated on the Mediterranean coast of Spain.