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2. Comparison of effects of salt and alkali stresses on the growth and photosynthesis of wheat
- Creator:
- Yang, C. W., Wang, P., Li, C. Y., Shi, D. C., and Wang, D. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- cartenoids, chlorophyll, NaCl, Na2CO3, NaHCO3, Na2SO4, stomatal conductance, transpiration rate, Triticum, and water use efficiency
- Language:
- Multiple languages
- Description:
- The seedlings of wheat were treated by salt-stress (SS, molar ratio of NaCl: Na2SO4 = 1:1) and alkali-stress (AS, molar ratio of NaHCO3: Na2CO3 = 1:1). Relative growth rate (RGR), leaf area, and water content decreased with increasing salinity, and the extents of the reduction under AS were greater than those under SS. The contents of photosynthetic pigments did not decrease under SS, but increased at low salinity. On the contrary, the contents of photosynthetic pigments decreased sharply under AS with increasing salinity. Under SS, the changes of net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) were similar and all varied in a single-peak curve with increasing salinity, and they were lower than those of control only at salinity over 150 mM. Under AS, PN, gs, and E decreased sharply with rising salinity. The decrease of gs might cause the obvious decreases of E and intercellular CO2 concentration, and the increase of water use efficiency under both stresses. The Na+ content and Na+/K+ ratio in shoot increased and the K+ content in shoot decreased under both stresses, and the changing extents under AS were greater than those under SS. Thus SS and AS are two distinctive stresses with different characters; the destructive effects of AS on the growth and photosynthesis of wheat are more severe than those under SS. High pH is the key feature of the AS that is different from SS. The buffer capacity is essentially the measure of high pH action on plant. The deposition of mineral elements and the intracellular unbalance of Na+ and K+ caused by the high pH at AS might be the reason of the decrease of PN and gs and of the destruction of photosynthetic pigments. and C. W. Yang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Dissipation of excess energy in Mehler-peroxidase reaction in Rumex leaves during salt shock
- Creator:
- Chen, H.-X., Gao, H.-Y., An, S.-Z., and Li, W.-J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, NaCl, net photosynthetic rate, non-photochemical quenching, oxygen concentration, quantum yield of photosystem 2, and stomatal conductance
- Language:
- Multiple languages
- Description:
- By measurement of gas exchange and chlorophyll fluorescence, the effects of salt shock on photosynthesis and the mechanisms to protect photosynthetic machinery against photodamage during salt shock were investigated in leaves of Rumex seedlings. Salt shock induced significant decrease in photosynthesis both in 21 and 2 % O2. In 21 % O2, quantum yield of photosystem 2 (PS2) electron transport (ΦPS2) decreased slightly and qP remained constant, suggesting that the excitation pressure on PS2 did not increase during salt shock. In 2 % O2, however, both ΦPS2 and qP decreased significantly, suggesting that the excitation pressure on PS2 increased during salt shock. NPQ increased slightly in 21 % O2 whereas it increased significantly in 2 % O2. The data demonstrated that during salt shock a considerable electron flow was allocated to oxygen reduction in the Mehler-peroxidase reaction (MPR). Under high irradiance and in the presence of saturating CO2, the susceptibility of PS2 to photoinhibition in salt-shocked leaves was increased when the electron flow to oxygen in MPR was inhibited in 2 % O2. Hence, MPR is important in photoprotection of Rumex seedlings during salt shock. and H.-X. Chen ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Effects of NaCl stress on the growth and photosynthetic characteristics of Ulmus pumila L. seedlings in sand culture
- Creator:
- Feng, Z. T., Deng, Y. Q., Fan, H., Sun, Q. J., Sui, N., and Wang, B. S.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, jilm, chlorid sodný, photosynthesis, Ulmus, sodium chloride, chlorophyll fluorescence, gas exchange, elm, growth, salt stress, sodium ion, NaCl, Ulmus pumila, 2, and 581
- Language:
- Multiple languages
- Description:
- The effects of NaCl stress on the growth and photosynthetic characters of Ulmus pumila L. seedlings were investigated under sand culture condition. With increasing NaCl concentration, main stem height, branch number, leaf number, and leaf area declined, while Na+ content and the Na+/K+ ratio in both expanded and expanding leaves increased. Na+ content was significantly higher in expanded leaves than in those just expanding. Chlorophyll (Chl) a and Chl b contents declined as NaCl concentration increased. The net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, and transpiration rate also declined, but stomatal limitation value increased as NaCl concentration increased. Both the maximal quantum yield of PSII photochemistry and the effective quantum yield of PSII photochemistry declined as NaCl concentration rose. These results suggest that the accumulation of Na+ in already expanded leaves might reduce damage to the expanding leaves and help U. pumila endure high salinity. The reduced photosynthesis in response to salt stress was mainly caused by stomatal limitation., Z. T. Feng, Y. Q. Deng, H. Fan, Q. J. Sun, N. Sui, B. S. Wang., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
5. Effects of salt stress on basic processes of photosynthesis
- Creator:
- Sudhir, P. and Murthy, S. D. S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carboxylases, carotenoids, chlorophyll, cyanobacteria, electron transport, eukaryotic algae, NaCl, photophosphorylation, photosynthetic rate, photosystems, phycobiliproteins, and salt tolerance
- Language:
- Multiple languages
- Description:
- Salt stress causes decrease in plant growth and productivity by disrupting physiological processes, especially photosynthesis. The accumulation of intracellular sodium ions at salt stress changes the ratio of K : Na, which seems to affect the bioenergetic processes of photosynthesis. Both multiple inhibitory effects of salt stress on photosynthesis and possible salt stress tolerance mechanisms in cyanobacteria and plants are reviewed. and P. Sudhir, S. D. S. Murthy.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
6. Induction of cyclic electron flow around photosystem 1 and state transition are correlated with salt tolerance in soybean
- Creator:
- Lu, K. X., Yang, Y., He, Y., and Jiang, D. A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence induction, DBMIB, DCMU, electron flow inhibitors, light-harvesting complex, maximum photochemical efficiency, NaCl, phosphorylation, species differences, and Western blot
- Language:
- Multiple languages
- Description:
- We investigated the role of cyclic electron flow around photosystem 1 (CEF1) and state transition (ST) in two soybean cultivars that differed in salt tolerance. The CEF1 and maximum photochemical efficiency (Fv/Fm) were determined under control and NaCl (50 mM) stress and the NaCl-induced light-harvesting complex 2 (LHC2) phosphorylation in vitro was analysed in light and dark. NaCl induced the increase of CEF1 more greatly in wild soybean Glycine cyrtoloba (cv. ACC547) than in cultivated soybean Glycine max (cv. Melrose). The Fv/Fm was reduced less in G. cyrtoloba than in G. max after 10-d NaCl stress. In G. cyrtoloba, the increase of CEF1 was associated with enhancement of LHC2 phosphorylation in thylakoid membrane under both dark and light. However, in G. max the NaCl treatment decreased the LHC2 phosphorylation. Treatment with photosynthetic electron flow inhibitors (DCMU, DBMIB) inhibited LHC2 phosphorylation more in G. max than in G. cyrtoloba. Thus the NaCl-induced up-regulation in CEF1 and ST might contribute to salt resistance of G. cyrtoloba. and K. X. Lu ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
7. Interaction of anions and cations in regulating energy distribution between the two photosystems
- Creator:
- Jajoo, Anjana and Bharti, Sudhakar
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence induction, MgCl2, NaCl, Na2HPO4, Na2PO4, Na2SO4, spinach, Spinacia oleracea, state change, and thylakoids
- Language:
- Multiple languages
- Description:
- Cations such as Mg2+ regulate spillover of absorbed excitation energy mainly in favour of photosystem (PS) 2. Effect of low concentration (<10 mM) of the monovalent cation Na+ on chlorophyll (Chl) a fluorescence was completely overridden by divalent cation Mg2+ (5 mM). Based on Chl a fluorescence yield and 77 K emission measurements, we revealed the role and effectiveness of anions (Cl-, SO42-, PO43-) in lowering the Mg2+-induced PS2 fluorescence. The higher the valency of the anion, the lesser was the expression of Mg2+ effect. Anions may thus overcome Mg2+ effects up to certain extent in a valency dependent manner, thereby diverting more energy to PS1 even in the presence of MgCl2. They may do so by reversing Mg2+-induced changes. and Anjana Jajoo, Sudhakar Bharti.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8. Interactive effects of salinity and ozone pollution on photosynthesis, stomatal conductance, growth, and assimilate partioning of wheat (Triticum aestivum L.)
- Creator:
- Hassan, I. A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll, ear, NaCl, O3, relative growth rate, shoot/root ratio, and 1 000 grain mass
- Language:
- Multiple languages
- Description:
- Plants of an Egyptian cultivar of wheat (Triticum aestivum L. cv. Giza 63) were exposed in open-top chambers (OTCs) for 8 h d-1 for up to 75 d to a factorial combination of two levels of salinity (0 and 50 mM NaCl) and two levels of O3 (filtered air and 50 mm3 m-3). Exposure to 50 mm3 m-3 O3 significantly decreased stomatal conductance (gs), net photosynthetic rate (PN), and chlorophyll (Chl) content by 20, 25, and 21 %, respectively. This reduction resulted in a change in assimilate allocation in favour of shoot growth leading to a decrease in root to shoot ratio and eventually to a decrease in relative growth rate (RGR) of both root and shoot. There was a very large reduction in yield parameters, especially in the number of ears/plant and 1 000-grain mass. Soil salinity significantly reduced PN and gs by 17 and 15 %, respectively, while Chl content was increased by 17 %. Root growth was decreased leading to an increase in root/shoot ratio. Yield parameters were decreased due to salt stress. There was antagonistic interaction between salinity (50 mM NaCl) and O3 (50 mm3 m-3) showing that salinity effectively protects against the adverse effects of O3 by increasing gs during O3 fumigation.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
9. Modular response to salinity in the annual halophyte, Salicornia ramosissima
- Creator:
- Redondo-Gómez, S., Mateos-Naranjo, E., Parra, R., and Figueroa, M. E.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, chlorophyll fluorescence, halophyte, modular response, and NaCl
- Language:
- Multiple languages
- Description:
- Chlorophyll fluorescence measurements showed that plasticity to salinity in stems of Salicornia ramosissima is expressed at a modular level, so intraplant variation should be considered in further studies. and S. Redondo-Gómez ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
10. Osmotic and atmospheric dehydration effects in the lichens Hypogymnia physodes, Lobaria pulmonaria, and Peltigera aphthosa: an in vivo study of the chlorophyll fluorescence induction
- Creator:
- Jensen, M., Chakir, Samira, and Feige, G. B.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- green algae, NaCl, sucrose, water potential, and water stress
- Language:
- Multiple languages
- Description:
- Inactivation of photosynthesis during atmospheric and osmotic (highly concentrated NaCl or sucrose solutions) dehydration was monitored by measurement of chlorophyll fluorescence induction (OIP-phase, Kautsky-curves) in three lichen species. The induction curves were changed in a very similar way by all three treatments. All dehydration effects were rapidly reversible after rehydration. At relatively mild water stress, the rise time to the transient peak Fp was prolonged, and the variable part of fluorescence was diminished. In addition, at severe water stress, a considerable decline of the F0 value was observed. For NaCl treatment this effect started at water potentials <-8.5 MPa in P. aphthosa, <-12 MPa in H. physodes, and <-21 MPa in L. pulmonaria. Above these water potentials, our observations are in agreement with values from desiccation-tolerant algae, higher plants, and lichens, where an inactivation on the photosystem 2 (PS2) donor side has been postulated. At very low water potentials, the decrease in F0 probably monitors changes in the organization of the antenna apparatus of PS2. and M. Jensen, Samira Chakir, G. B. Feige.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public