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2. Comparative anatomical, morphological, and physiological parameters controlling photosynthesis in two Populusxeuramericana clones during short-term osmotic treatment
- Creator:
- Courtois, M., Boudouresque, E., and Guerrier, G.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- active oxygen species, aminolevulinate dehydratase, antioxidants, carboxylation, carotenoids, chlorophyll, chlorophyllase, poplar, ribulose-1,5-bisphosphate carboxylase, oxygenase, and stomatal conductance
- Language:
- Multiple languages
- Description:
- The relationships between drought response and anatomical/physiological properties were assessed in two poplar clones belonging to the Aigeros section: Populusxeuramericana clone Dorskamp (drought-tolerant) and clone Luisa Avanzo (drought-sensitive). Cuttings of both clones were exposed for 12 h to 0 mM (control). 50 mM (osmotic potential -0.112 MPa), and 150 mM (-0.336 MPa) mannitol. In control, Dorskamp had smaller stomata than Luisa Avanzo, one or two layers of palisade cells, a spongy mesophyll, and high concentrations of antioxidative compounds (ascorbate, glutathione). After exposure to 50 or 150 mM mannitol, both clones closed their stomata: leaf conductance and opening of stomata decreased. When exposed to 50 mM mannitol, net photosynthetic rate (PN) and chlorophyll (Chl) and total solute contents remained stable; ribulose-1,5-bisphosphate carboxylase/-oxygenase activity, Chl synthesis and turn-over, ascorbate peroxidase and glutathione reductase activities were less affected in Dorskamp than in Luisa Avanzo. Following an exposure to 150 mM mannitol, Dorskamp exhibited higher PN and higher contents of antioxidants (ascorbate, glutathione) and antioxidative enzymes (ascorbate peroxidase, glutathione reductase) than Luisa Avanzo. Hence the drought-tolerant poplar was able to better avoid and tolerate osmotic stress. and M. Courtois, E. Boudouresque, G. Guerrier.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Comparison of the effects of salt-stress and alkali-stress on photosynthesis and energy storage of an alkali-resistant halophyte Chloris virgata
- Creator:
- Yang, C. W., Jianaer, A., Li, C. Y., Shi, D. C., and Wang, D. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll, leaf area, photosynthetic rate, relative growth rate, stomatal conductance, transpiration rate, and water content
- Language:
- Multiple languages
- Description:
- Seedlings of Chloris virgata were treated with varying (0-160 mM) salt-stress (SS; 1 : 1 molar ratio of NaCl to Na2SO4) or alkali-stress (AS; 1 : 1 molar ratio of NaHCO3 to Na2CO3). To compare these effects, relative growth rates (RGR), stored energy, photosynthetic pigment contents, net photosynthetic rates, stomatal conductance, and transpiration rates were determined. Both stresses did not change significantly the photosynthetic parameters of C. virgata under moderate stress (below 120 mM). Photosynthetic ability decreased significantly only at high stress (160 mM). Thus C. virgata, a natural alkali-resistant halophyte, adapts better to both kinds of stress. The inhibition effects of AS on RGR and energy storage of C. virgata were significantly greater than that of SS of the same intensity. The energy consumption of C. virgata was considerably greater while resisting AS than while resisting SS. and C. W. Yang ... [et al.]
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Drought tolerance in the Mediterranean species Quercus coccifera, Quercus ilex, Pinus halepensis, and Juniperus phoenicea
- Creator:
- Baquedano, F. J. and Castillo, F. J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll fluorescence, field conditions, net photosynthetic rate, photosystem 2, precipitation, quantum yield, stomatal conductance, transpiration, and water potential
- Language:
- Multiple languages
- Description:
- We investigated the strategies of four co-occurring evergreen woody species Quercus ilex, Quercus coccifera, Pinus halepensis, and Juniperus phoenicea to cope with Mediterranean field conditions. For that purpose, stem water potential, gas exchange, chlorophyll (Chl) fluorescence, and Chl and carotenoid (Car) contents were examined. We recognized two stress periods along the year, winter with low precipitation and low temperatures that led to chronic photoinhibition, and summer, when drought coincided with high radiation, leading to an increase of dynamic photoinhibition and a decrease of pigment content. Summer photoprotection was related to non-photochemical energy dissipation, electron flow to alternative sinks other than photosynthesis, decrease of Chl content, and proportional increase of Car content. Water potential of trees with deep vertical roots (Q. coccifera, Q. ilex, and P. halepensis) mainly depended on precipitation, whereas water potential of trees with shallow roots (J. phoenicea) depended not only on precipitation but also on ambient temperature. and F. J. Baquedano, F. J. Castillo.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
5. Effects of buffer capacity on growth, photosynthesis, and solute accumulation of a glycophyte (wheat) and a halophyte (Chloris virgata)
- Creator:
- Yang, C.-W., Zhang, M.-L., Liu, J., Shi, D.-C., and Wang, D.-L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- alkali-stress, carotenoids, Chloris virgata, chlorophyll, K+, Na+, organic acids, proline, salt stress, stomatal conductance, transpiration rate, and wheat
- Language:
- Multiple languages
- Description:
- Two species with different resistances to alkaline pH, the glycophylic Triticum aestivum (wheat) and the halophilic Chloris virgata, were chosen as test organisms. The salt-alkaline (SA) mixed stress conditions with different buffer capacities (BC) but with the same salt molarities and pH were established by mixing neutral (NaCl, Na2SO4), and alkaline salts (NaHCO3 and Na2CO3) in various proportions. Growth, photosynthetic characteristics, and solute accumulation of the seedlings were monitored to test the validity of BC as a decisive index of alkali-stress (AS) intensity in SA mixed stress. At the same salinities and pHs, the relative growth rate, the content of photosynthetic pigments, and net photosynthetic rates of wheat and C. virgata decreased, while Na+ content and Na+/K+ ratios in shoots increased with increasing BC. Hence BC was a true measure of AS intensity at mixed SA stress and the alkali-resistance mechanism of plants was easy to interpret. BC of soil solution is an important parameter for estimating the alkalization degree of salt-alkalized soil. and C.-W. Yang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
6. Effects of rhizobia inoculation and nitrogen fertilization on photosynthetic physiology of soybean
- Creator:
- Zhou, X.-J., Liang, Y., Chen, H., Shen, S.-H., and Jing, Y.-X.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- biological nitrogen fixation, biomass, carboxylation efficiency, carotenoids, chlorophyll fluorescence, Glycine max, intercellular CO2 concentration, leaf area, stomatal conductance, and quantum yield
- Language:
- Multiple languages
- Description:
- Plant growth, contents of photosynthetic pigments, photosynthetic gas exchange, and chlorophyll (Chl) fluorescence in soybean [Glycine max (L.) Merr. cv. Heinong37] were investigated after it was inoculated with Sinorhizobium fredii USDA191 or treated with 5 mM (NH4)2SO4 (N5) and 30 mM (NH4)2SO4 (N30), respectively. In the plants following N5 fertilization, not only plant biomass, leaf area, and Chl content, but also net photosynthetic rate (PN), stomatal conductance (gs), carboxylation efficiency (CE), maximum photochemical efficiency (Fv/Fm) of photosystem 2 (PS2), and quantum yield of PS2 (ΦPS2) were markedly improved as compared with the control plants. There were also positive effects on plant growth and plant photosynthesis after rhizobia inoculation, but the effects were much less than those of N5 fertilization. For N30 plants there were no significant positive effects on plant growth and photosynthetic capacity. Plant biomass, PN, and gs were similar to those of N-limited (control) plants. ΦPS2 and photochemical quenching (qP) were obviously declined while content of carotenoids and non-photochemical quenching (qN) were significantly enhanced in N30 treated plants. This indicated that excess N supply may cause some negative effects on soybean plants. and X.-J. Zhou ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7. Gas exchange and water relations of three Vitis vinifera L. cultivars growing under Mediterranean climate
- Creator:
- Moutinho-Pereira, J., Magalhães, N., Gonçalves, B., Bacelar, E., Brito, M., and Correia, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll, internal CO2 concentration, leaf water potential, net photosynthetic rate, optical characteristics, stomatal conductance, starch and sugars, transpiration rate, and water use efficiency
- Language:
- Multiple languages
- Description:
- Optical characteristics, contents of photosynthetic pigments, total soluble sugars, and starch, rates of gas exchange, chlorophyll (Chl) a fluorescence, and leaf water relations were analysed in three Vitis vinifera L. cultivars, Tinto Cão (TC), Touriga Nacional (TN), and Tinta Roriz (TR), grown in Mediterranean climate. Chl content was significantly lower in TC than in TN and TR leaves, while the Chl a/b ratio was higher. TR had the lowest net photosynthetic rate, stomatal conductance, and contents of soluble sugars and starch than TN and TC. In spite of low Chl content, TC showed the lowest photon absorbance and the highest photochemical efficiency of photosystem 2. TC had the lowest predawn and midday leaf water potential. The capability for osmotic adjustment was similar among cultivars and the calculated modulus of elasticity was higher in TC leaves. The typical lighter green leaves of TC seemed to be an adaptive strategy to high irradiance and air temperature associated to water stress. and J. Moutinho-Pereira ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8. Gas exchange in senescing leaves of Olea europaea L.
- Creator:
- Proietti, P.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll, detachment force, nitrogen content, olive, respiration rate, saccharides, stomatal conductance, and transpiration rate
- Language:
- Multiple languages
- Description:
- From the beginning of olive leaf yellowing to leaf fall (1/3 months), there was a general trend from anabolism to catabolism. Rates of net photosynthesis (PN) and respiration, areal dry mass, and contents of pigments, particularly of chlorophyll (Chl) a, starch, and above all nitrogen (N) decreased. The detachment force decreased dramatically only in completely chlorotic leaves. Chl a : b ratio only declined in the last 10-20 d of senescence, when the total Chl contents diminished by about 70 %, after which the N content, PN, and efficiency of the photochemical energy conversion of the remaining Chl and N dramatically declined. Consequently, for most of the natural course of senescence PN remained relatively high. The reduction in PN was associated with the decreases in transpiration rate (E) and stomatal conductance (gs), but these probably did not cause the decline of PN. The recycling of saccharide compounds was low, while 50 % of the total N on a leaf area basis was relocated back before leaf abscission, changing the leaf from a carbon source to a mineral source. Therefore, considering that senescing leaves in olive trees contribute to carbon gain and allow the recycling of resources, it is essential to prevent the premature leaf abscission by avoiding deficits of water and mineral nutrients and by using pruning and training systems that allow good irradiation of all leaves in the crown.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
9. Influence of water stress and low irradiance on morphological and physiological characteristics of Picea asperata seedlings
- Creator:
- Yang, Y., Liu, Q., Han, C., Qiao, Y. Z., Yao, X. Q., and Yin, H. J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll fluorescence, growth, photosynthesis, photosystem 2, quantum yield, root/shoot raton, specific leaf area, stomatal conductance, and transpiration
- Language:
- Multiple languages
- Description:
- The combined effects of water stress (WS) and low irradiance (LI) on growth, photosynthesis, osmotic adjustment, and lipid peroxidation were studied in dragon spruce (Picea asperata Mast.) seedlings grown under two water treatments (well watered, 100 % of field capacity, and water stressed, 30 % of field capacity) and two irradiances (HI, 100 % of full sunlight and LI, 15 % of full sunlight). WS reduced growth, chlorophyll (Chl) a and b contents, net photosynthetic rate, transpiration rate, stomatal conductance, and effective quantum yield of photosystem 2 (Y) but increased free proline and malondialdehyde contents. LI increased Chl contents and decreased Y, photochemical quenching (qP), and non-photochemical quenching (qN) under both water treatments. Hence the seedlings in the understory were more sensitive to drought than to LI. and Y. Yang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
10. Photosynthesis and photosystem 2 efficiency of two salt-adapted halophytic seashore Cakile maritima ecotypes
- Creator:
- Megdiche, W., Hessini, K., Gharbi, F., Jaleel, C. A., Ksouri, R., and Abdelly, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophylls, fluorescence, intracellular CO2 concentration, quenching, relative growth rate, salt tolerance, stomatal conductance, iranspiration rate, and water use efficiency
- Language:
- Multiple languages
- Description:
- The effects of salinity (0-400 mM NaCl, marked S0, S100, S200, and S400) on growth, photosynthesis, photosystem 2 (PS2) efficiency, ion relations, and pigment contents were studied in two seashore Cakile maritima ecotypes (Tabarka and Jerba, respectively, sampled from humid and arid bioclimatic areas). Growth of Jerba plants was improved at S100 as compared to S0. Tabarka growth was inhibited by salinity at all NaCl concentrations. Leaf sodium and chloride concentrations increased with medium salinity and were higher in Jerba than in Tabarka plants. Chlorophyll content, net photosynthetic rate, stomatal conductance (gs), and intracellular CO2 concentration were stimulated at moderate salinity (S100) in Jerba plants and inhibited at higher salt concentrations in both ecotypes: gs was the most reduced parameter. The maximum quantum efficiency of PS2 (Fv/Fm), quantum yield, linear electron transport rate, and efficiency of excitation energy capture by open PS2 reaction centres showed no significant changes with increasing salt concentration in Jerba plant and were decreased in Tabarka subjected to S400. However, the efficiency of dissipation of excess photon energy in the PS2 antenna was maintained in Jerba and was increased in Tabarka plants challenged with S400. Hence the relative salt tolerance of Jerba was associated with a better ability to use Na+ and Cl- for osmotic adjustment, the absence of pigment degradation, and the concomitant PS2 protection from photodamage. and W. Megdiche ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public