Effects of Enhanced UV-B Radiation on the Drought Semi-deciduous Mediterranean Shrub Phlomis fruticosa under Field Conditions are Season-specific

1995 ◽  
Vol 22 (5) ◽  
pp. 737 ◽  
Author(s):  
D Nikolopoulos ◽  
Y Petropoulou ◽  
A Kyparissis ◽  
Y Manetas
Keyword(s):  
Developmental Stages ◽  
Stratospheric Ozone ◽  
Photochemical Efficiency ◽  
Net Photosynthesis ◽  
Experimental Period ◽  
Dry Mass ◽  
Photosynthetic Performance ◽  
Photosynthetic Parameters ◽  
Summer Drought ◽  
Total Carotenoids

The effects of enhanced UV-B radiation on Phlomis fruticosa L. were recorded during a 1- year field study. Plants received ambient or ambient plus supplemental UV-B radiation (simulating a 15% stratospheric ozone depletion over Patras, 38.3�N, 29.1�E) and only natural precipitation, i.e. they were simultaneously exposed to other natural stresses, particularly water stress during summer. Actual, biologically equivalent UV-B doses were 8.55 and 11.21 kJ m-2 day-1 during the summer maximum (14 July) and 0.85 and 1.12 kJ m-2 day-1 during the winter minimum (27 December) for control and W-B plants respectively, while intermediate values were received for the rest of the year. lho seasonally separated effects could be distinguished. The first was a growth response, observed at late spring, in the absence of any simultaneous stress and at the period most favourable for this shrub, during which it shows maximum photosynthetic performance. The effect was an inhibition of new leaf development and premature falling of old leaves, leading to lower leaf numbers and total leaf areas for the rest of the experimental period. The second effect coincided with the summer drought, during which net photosynthesis, chlorophyll content and photochemical efficiency of photosystem II decreased in the controls, but a trend towards a further decrease in W-B irradiated plants was also evident. Changes in total carotenoids were negligible, leading to higher carotenoid to chlorophyll ratios under enhanced W-B radiation. Photosynthetic parameters recovered to the same levels in control and UV-B irradiated plants after the first heavy rains in autumn. At final harvest, considerable decreases in total dry mass were evident for UV-B irradiated plants, while plant height, UV-B-absorbing compounds, relative water content and leaf specific mass were unaffected during the whole experimental period. UV-B effects may depend not only on co-occumng natural stresses, but on the specific sensitivity of individual developmental stages as well, i.e. they may be season-specific.

scholarly journals Photosynthetic performance in Eucalyptus clones cultivated in saline soil

2019 ◽  
pp. 368
Author(s):  
Jailma Ribeiro de Andrade ◽  
Sebastião de Oliveira Maia Júnior ◽  
Andrea Francisca da Silva Santos ◽  
Vicente Mota da Silva ◽  
L.T. Bezerra, J.R.R. da Silva, C.M. Santos, V.M. Ferreira, L. Endres
Keyword(s):  
Salt Stress ◽  
Block Design ◽  
Photosynthetic Pigment ◽  
Photochemical Efficiency ◽  
Dry Mass ◽  
Photosynthetic Performance ◽  
Saline Stress ◽  
Physiological Indicators ◽  
Photochemical Efficiency Of Psii ◽  
Randomized Block Design

The aim of this study was to evaluate the photosynthetic performance of Eucalyptus clones with the aim of identifying their tolerance to soil saline stress conditions. The experiment was arranged in a randomized block design with a 3 × 4 factorial arrangement: in five replications, totaling 60 plots, three Eucalyptus clones were used, VC865, I224, and I144, which were exposed to four concentrations of NaCl (0, 1, 2 and 3 g NaCl kg-1 of soil). Clone I144 shows mechanisms of salinity tolerance as smaller reductions in the stomatal conductance, transpiration, photosynthesis, photochemical efficiency of PSII, photosynthetic pigment content and total dry mass. On the other hand, clone I224 presents greater physiological damage, indicating high susceptibility to salt stress, while VC865 shows moderate sensitivity to salinity. Variables related to photosynthetic performance, such as gas exchange, photochemical efficiency of PSII and photosynthetic pigments are potentially reliable physiological indicators for selecting of tolerant Eucalyptus clones to salt stress.

scholarly journals EFFECT OF CHILLING STRESS ON THE PHOTOSYNTHETIC PERFORMANCE OF YOUNG PLANTS FROM TWO MAIZE (ZEA MAYS) HYBRIDS

2017 ◽  
Vol 5 ◽  
pp. 1118-1123 ◽  
Author(s):  
Rositsa Cholakova-Bimbalova ◽  
Andon Vassilev
Keyword(s):  
Lipid Peroxidation ◽  
Transition Period ◽  
Chilling Stress ◽  
Experimental Period ◽  
Photosynthetic Performance ◽  
Photochemical Quenching ◽  
Photosynthetic Parameters ◽  
Climate Conditions ◽  
Maize Plants ◽  
Non Photochemical Quenching

: In the climate conditions of Bulgaria, early stages of maize plants development often go under suboptimal temperatures. Chilling stress is known to cause different physiological disturbances in young maize plants during the transition period from heterotrophic to autotrophic nutrition. However, the effect of chilling may differ among maize hybrids. Photosynthetic performance could be a good indicator for the hybrid tolerance to chilling. The aim of our study was to evaluate the tolerance of young maize plants from two hybrids – the new Bulgarian hybrid - Kneza 307 and the hybrid P9528 using as criteria the changes in their photosynthetic performance.Plants at the third leaf stage were exposed for seven days to chilling stress. At the end of the experimental period, growth, leaf lipid peroxidation, and several photosynthetic parameters were measured. We found that chilling stress reduced the fresh mass accumulation, increased lipid peroxidation, diminished net photosynthetic rate and chlorophyll content, and enhanced non-photochemical quenching of chlorophyll fluorescence. Although the responses of both hybrids were similar, some specificity were observed and discussed.

Do volatile organic compound emissions of Tunisian cork oak populations originating from contrasting climatic conditions differ in their responses to summer drought?

2008 ◽  
Vol 38 (12) ◽  
pp. 2965-2975 ◽  
Author(s):  
Michael Staudt ◽  
Amel Ennajah ◽  
Florent Mouillot ◽  
Richard Joffre
Keyword(s):  
Organic Compound ◽  
Gas Exchange ◽  
Volatile Organic Compound ◽  
Photochemical Efficiency ◽  
Photosynthetic Parameters ◽  
Severe Drought ◽  
Summer Drought ◽  
Partial Recovery ◽  
Volatile Organic ◽  
Volatile Organic Compound Emissions

The intrinsic variability of volatile organic compound emissions and photosynthetic parameters in response to two drying cycles was investigated on Quercus suber L. saplings originating from three Tunisian populations native to contrasting climates. Emissions mainly included monoterpenes plus traces of sesquiterpenes and methylsalicylate that steadily decreased during the experiment unrelated to treatments. Instead, monoterpene emissions increased by 30% during a first moderate drought and remained enhanced after rewatering, while CO2–H2O gas exchange was reduced by 30%. A second severe drought decreased monoterpene emissions to about two third of controls, strongly inhibited gas exchange and photochemical efficiency, and caused a partial loss of chlorophyll. Rewatering led to only partial recovery of emissions and photosynthetic parameters of stressed plants whose biomasses and leaf nitrogen and chlorophyll contents were lower than in control plants. There was no clear difference among populations in volatile organic compound emissions or photosynthetic parameters. However, the population inhabiting the most arid region had intrinsically smaller leaves with lower specific leaf masses and higher drought-related leaf losses than populations native to less arid climates. These results indicate an adaptive shift from stress-tolerating towards stress-avoiding ecotypes under arid climates involving mainly morphological adaptations without apparent differentiation in volatile organic compound production, probably because of its high phenological plasticity.

Salinity effects on chloroplast PSII performance in glycophytes and halophytes

2016 ◽  
Vol 43 (11) ◽  
pp. 1003 ◽  
Author(s):  
William J. Percey ◽  
Andrew McMinn ◽  
Jayakumar Bose ◽  
Michael C. Breadmore ◽  
Rosanne M. Guijt ◽  
...  
Keyword(s):  
Critical Role ◽  
Photochemical Efficiency ◽  
Chenopodium Quinoa ◽  
Nacl Stress ◽  
Photosynthetic Performance ◽  
K Channel ◽  
Photosynthetic Parameters ◽  
Atpase Inhibitor ◽  
Mesophyll Cells ◽  
Isolated Chloroplasts

The effects of NaCl stress and K+ nutrition on photosynthetic parameters of isolated chloroplasts were investigated using PAM fluorescence. Intact mesophyll cells were able to maintain optimal photosynthetic performance when exposed to salinity for more than 24 h whereas isolated chloroplasts showed declines in both the relative electron transport rate (rETR) and the maximal photochemical efficiency of PSII (Fv/Fm) within the first hour of treatment. The rETR was much more sensitive to salt stress compared with Fv/Fm, with 40% inhibition of rETR observed at apoplastic NaCl concentration as low as 20 mM. In isolated chloroplasts, absolute K+ concentrations were more essential for the maintenance of the optimal photochemical performance (Fv/Fm values) rather than sodium concentrations per se. Chloroplasts from halophyte species of quinoa (Chenopodium quinoa Willd.) and pigface (Carpobrotus rosii (Haw.) Schwantes) showed less than 18% decline in Fv/Fm under salinity, whereas the Fv/Fm decline in chloroplasts from glycophyte pea (Pisum sativum L.) and bean (Vicia faba L.) species was much stronger (31 and 47% respectively). Vanadate (a P-type ATPase inhibitor) significantly reduced Fv/Fm in both control and salinity treated chloroplasts (by 7 and 25% respectively), whereas no significant effects of gadolinium (blocker of non-selective cation channels) were observed in salt-treated chloroplasts. Tetraethyl ammonium (TEA) (K+ channel inhibitor) and amiloride (inhibitor of the Na+/H+ antiporter) increased the Fv/Fm of salinity treated chloroplasts by 16 and 17% respectively. These results suggest that chloroplasts’ ability to regulate ion transport across the envelope and thylakoid membranes play a critical role in leaf photosynthetic performance under salinity.

scholarly journals THE EFFECTS OF ALUMINIUM ON THE PHOTOSYNTHETIC APPARATUS OF TWO RICE CULTIVARS

2013 ◽  
Vol 50 (3) ◽  
pp. 343-352 ◽  
Author(s):  
E. M. FONSECA JÚNIOR ◽  
J. CAMBRAIA ◽  
C. RIBEIRO ◽  
M. A. OLIVA ◽  
J. A. OLIVEIRA ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photochemical Efficiency ◽  
Photosynthetic Apparatus ◽  
Carbon Assimilation ◽  
Biomass Accumulation ◽  
Dry Mass ◽  
Photochemical Quenching ◽  
Photosynthetic Parameters ◽  
Rice Cultivars

SUMMARYWe aimed to evaluate aluminium (Al) effects on the photosynthetic apparatus of two rice cultivars with contrasting tolerances to Al. Nine-days-old seedlings were exposed to 0 or 1 mM Al for 10 days, and then dry mass, Al and chloroplastidic pigment contents and photosynthetic parameters were determined. Al accumulated mainly in the roots of the Al-treated plants. In the leaves, Al increased only in the sensitive cultivar, but there was no difference between the cultivars in Al-treated plants. The root and leaf dry mass, the net carbon assimilation rate, stomatal conductance and internal CO2 concentration were all reduced in response to Al application, but only in the sensitive cultivar. Both the initial fluorescence and potential photochemical efficiency of photosystem II were unresponsive to the Al treatments, regardless of the cultivar. In the Al-sensitive cultivar, Al provoked significant decreases in the photochemical quenching coefficient, quantum yield of photosystem II electron transport and apparent electron transport rate, in parallel to an unaltered non-photochemical quenching coefficient. All of these parameters remained at the control levels in the tolerant cultivar. The chloroplastidic pigment content increased only in the Al-tolerant cultivar, whereas it remained unaltered after Al treatment in the sensitive cultivar. In conclusion, Al induced stomatal and (most likely) photochemical constraints on photosynthesis but with no apparent signs of photoinhibition in the Al-sensitive cultivar. Despite the similar Al levels of the cultivars, unchanging biomass accumulation or photosynthetic performance in the tolerant cultivar challenged with Al highlights its higher intrinsic ability to cope with Al stress.

scholarly journals Uniform Water Potential Induced by Salt, Alkali, and Drought Stresses Has Different Impacts on the Seedling of Hordeum jubatum: From Growth, Photosynthesis, and Chlorophyll Fluorescence

2021 ◽  
Vol 12 ◽  
Author(s):  
Congcong Shi ◽  
Fan Yang ◽  
Zihao Liu ◽  
Yueming Li ◽  
Xiaolin Di ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Water Potential ◽  
Photochemical Efficiency ◽  
Photosynthetic Performance ◽  
Photochemical Quenching ◽  
Photosynthetic Parameters ◽  
Alkali Stress ◽  
Gas Exchange Parameters ◽  
Hordeum Jubatum ◽  
Damaging Effects

Hordeum jubatum is a halophyte ornamental plant wildly distributed in the Northeast of China, where the low water potential induced by various abiotic stresses is a major factor limiting plant growth and development. However, little is known about the comparative effects of salt, alkali, and drought stresses at uniform water potential on the plants. In the present study, the growth, gas exchange parameters, photosynthetic pigments, and chlorophyll fluorescence in the seedlings of H. jubatum under three low water potentials were measured. The results showed that the growth and photosynthetic parameters under these stresses were all decreased except for carotenoid (Car) with the increasing of stress concentration, and alkali stress caused the most damaging effects on the seedlings. The decreased net photosynthetic rate (Pn), stomatal conductance (Gs), and intercellular CO2 concentrations (Ci) values under salt stress were mainly attributed to stomatal factors, while non-stomatal factors were dominate under drought and alkali stresses. The reduced chlorophyll and slightly increased Car contents occurred under these stresses, and most significant changed under alkali stress. In addition, the maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII), and photochemical quenching coefficient (qP) under the stresses were all decreased, indicating that salt, alkali, and drought stresses all increased susceptibility of PSII to photoinhibition, reduced the photosynthetic activity by the declined absorption of light for photochemistry, and increased PSII active reaction centers. Moreover, the non-photochemical quenching coefficient (NPQ) of alkali stress was different from salt and drought stresses, showing that the high pH of alkali stress caused more damaging effects on the photoprotection mechanism depending on the xanthophyll cycle. The above results suggest that the H. jubatum has stronger tolerance of salt than drought and alkali stresses, and the negative effects of alkali stress on the growth and photosynthetic performance of this species was most serious.

scholarly journals Heat Stress at Early Reproductive Stage Differentially Alters Several Physiological and Biochemical Traits of Three Tomato Cultivars

Horticulturae ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 330
Author(s):  
Md. Sabibul Haque ◽  
Mst. Tanziatul Husna ◽  
Md. Nesar Uddin ◽  
Md. Alamgir Hossain ◽  
Abul Khayer Mohammad Golam Sarwar ◽  
...  
Keyword(s):  
Heat Stress ◽  
Ascorbate Peroxidase ◽  
Heat Tolerance ◽  
Photochemical Efficiency ◽  
Dry Mass ◽  
Carotenoid Content ◽  
Biochemical Traits ◽  
Total Carotenoids ◽  
Tomato Cultivars ◽  
Physiological And Biochemical

Global warming is predicted to be increased in the upcoming years, resulting in frequent heatwaves or hot days worldwide, which can seriously affect crop growth and productivity. The responses of heat stress to several photophysiological and biochemical traits in three tomato cultivars were investigated in a pot experiment, and the heat tolerance capability of these cultivars was evaluated based on the investigated traits. The experiment was followed by a factorial completely randomized design, and the factors were (i) tomato cultivars (BARI Hybrid Tomato-5, BARI Tomato-14, and BARI Tomato-15) and (ii) heat stress (control and heat). The plants of three tomato cultivars were exposed to short-term heat stress (four days at 38/25 °C day/night temperature) at the flowering stage. The measured traits such as dry mass, leaf greenness (SPAD), maximum photochemical efficiency of photosystem II (Fv/Fm), photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), leaf chlorophyll, and carotenoid content were significantly declined, while the catalase and ascorbate peroxidase activities were increased by heat stress in all three tomato cultivars except BARI Tomato-15, which showed unaltered gs, E, and carotenoids. The percent reduction (over control) in SPAD, Fv/Fm, A, total chlorophyll, and total carotenoids was significantly lower (11, 06, 25, 34, and 19%, respectively), whereas the percent increase in catalase and ascorbate peroxidase activities was substantially higher (70 and 72%, respectively) in BARI Tomato-15 than in other cultivars. Based on the measured physiological and biochemical traits, the cultivar BARI Tomato-15 showed better heat tolerance than the other cultivars.

scholarly journals THE GROWTH, PHOTOSYNTHETIC PARAMETERS AND NITROGEN STATUS OF BASIL, CORIANDER AND OREGANO GROWN UNDER DIFFERENT LED LIGHT SPECTRA

2021 ◽  
Vol 20 (2) ◽  
pp. 13-22
Author(s):  
Bożena Matysiak ◽  
Artur Kowalski
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Photochemical Efficiency ◽  
Photosynthetic Performance ◽  
Photosynthetic Parameters ◽  
Nitrogen Status ◽  
White Leds ◽  
Light Spectra ◽  
Plant Level ◽  
Led Lights

Growth, morphological parameters, photosynthetic performance and nitrogen status were investigated in leafy herbs grown in light-limited time in a greenhouse under different light spectra emitted by LEDs. Fluorescence-based sensors that detect crop N status and maximum photochemical efficiency of photosystem II were used in this study. Four light treatments with the ratio of Red, Blue and White LEDs including 1) R40 + B50 + W10, 2) R70 + B20 + W10, 3) R70 + B20 + W10 + Far-Red and 4) White LEDs as control were used in this study. Dominant red light and/or white LED lights at 200 µmol m–2 s–1 at plant level and a 12 h photoperiod provided the most favourable conditions for plant growth and development compared to a high proportion of blue light (R40 + B50 + W10). However, plants grown under a high proportion of blue light had a higher chlorophyll index and nitrogen balance index (NBI) than under dominant red light treatments. Our study indicates the significant potential of fluorescence-based sensors in photobiology research as well as in the production of leafy herbs under LED lights.

scholarly journals Growth analysis of Fafia in relation to the propagation method used

2008 ◽  
Vol 26 (3) ◽  
pp. 375-378 ◽  
Author(s):  
André May ◽  
Odair A Bovi ◽  
Nilson B Maia ◽  
Andrea RA de Moraes ◽  
Mariane Q Pinheiro
Keyword(s):  
Experimental Design ◽  
Aerial Part ◽  
Growth Analysis ◽  
Experimental Period ◽  
Dry Mass ◽  
Plant Propagation ◽  
Pfaffia Glomerata ◽  
Accumulation Curves ◽  
Propagation Methods ◽  
Mass Accumulation

A trial was carried out in Campinas, Brazil, from August 2005 to August 2006, in order to analyze the effect of two propagation methods (seeds and cuttings) on the development of Pfaffia glomerata (Spreng.) Pedersen. The experimental design was a completely randomized block, with five replications, and two methods of plant propagation. Plant height, aerial part dry mass and root dry mass were evaluated. Plants propagated from cuttings showed greater accumulation of dry mass on the aerial part. Root dry mass accumulation curves showed an exponential pattern, and at the end of the experimental period, the average of roots dry mass for both treatments were similar, up to 349,65 g plant-1.

scholarly journals Drought reduced monoterpene emissions from the evergreen Mediterranean oak <i>Quercus ilex</i>: results from a throughfall displacement experiment

2009 ◽  
Vol 6 (7) ◽  
pp. 1167-1180 ◽  
Author(s):  
A.-V. Lavoir ◽  
M. Staudt ◽  
J. P. Schnitzler ◽  
D. Landais ◽  
F. Massol ◽  
...  
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Quercus Ilex ◽  
Photochemical Efficiency ◽  
Leaf Water ◽  
Control Treatment ◽  
Summer Drought ◽  
Drought Period ◽  
Significant Difference ◽  
Monoterpene Emission

Abstract. The effects of water limitations on the emission of biogenic volatile organic compounds are not well understood. Experimental approaches studying drought effects in natural conditions are still missing. To address this question, a throughfall displacement experiment was set up in a natural forest of Quercus ilex, an evergreen Mediterranean oak emitting monoterpenes. Mature trees were exposed in 2005 and 2006 either to an additional drought, to irrigation or to natural drought (untreated control). In both years, absolute monoterpene emission rates as well as the respective standard factors of the trees exposed to normal and additional drought strongly declined during the drought periods. Monoterpene emissions were lower in year 2006 than in year 2005 (factor 2) due to a more pronounced summer drought period in this respective year. We observed a significant difference between the irrigation and additional drought or control treatment: irrigated trees emitted 82% more monoterpenes during the drought period 2006 than the trees of the other treatments. However, no significant effect on monoterpene emission was observed between normal and additional drought treatments, despite a significant effect on leaf water potential and photochemical efficiency. During the development of drought, monoterpene emissions responded exponentially rather than linearly to decreasing leaf water potential. Emissions rapidly declined when the water potential dropped below −2 MPa and photosynthesis was persistently inhibited. Monoterpene synthase activities measured in vitro showed no clear reduction during the same period. From our results we conclude that drought significantly reduces monoterpene fluxes of Mediterranean Holm oak forest into the atmosphere due to a lack of primary substrates coming from photosynthetic processes.

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