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2. Effect of imazapic residues on photosynthetic traits and chlorophyll fluorescence of maize seedlings
- Creator:
- Su, W. C., Sun, L. L., Wu, R. H., Ma, Y. H., Wang, H. L., Xu, H. L., Yan, Z. L., and Lu, C. T.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fluorescence chlorofylu, výměna plynu, růstové charakteristiky, fotosystém II, chlorophyll fluorescence, gas exchange, growth characteristics, photosystem II, 2, and 581
- Language:
- Multiple languages
- Description:
- The influence of various concentrations of imazapic residues (0-800 μg kg-1) on the growth, chlorophyll content, and photosynthetic characteristics of maize seedlings was studied in a greenhouse pot experiment. Plant height, root length, shoot dry mass, root dry mass, and total dry mass of maize declined with the increase of imazapic residue concentrations. The root/shoot ratio initially decreased and then increased in presence of imazapic, which indicated that the effects of imazapic residues on plant height and root length might differ in maize seedlings. Lowered chlorophyll content and net photosynthetic rate were observed in leaves of maize seedlings in all treatments and indicated a dose-response relationship to imazapic concentrations. Intercellular carbon dioxide concentration, transpiration rate, and stomatal conductance also declined to varying extents, but the chlorophyll a/b ratio increased gradually together with the increase of imazapic residue concentrations. Generally, the maize seedlings were negatively affected by the imazapic residues in soil. Response of root length and biomass to imazapic residues could be the important index for maize variety selection., W. C. Su, L. L. Sun, R. H. Wu, Y. H. Ma, H. L. Wang, H. L. Xu, Z. L. Yan, C. T. Lu., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Effects of 5-aminolevulinic acid treatment on photosynthesis of strawberry
- Creator:
- Sun, Y. P., Liu, J., Cao, R. X., Huang, Y. J., Hall, A. M., Guo, C. B., and Wang, L. J.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- jahody, strawberries, fluorescence chlorofylu, výměna plynu, tepelná fáze, fotochemická fáze, fotosystém I, fotosystém II, jahodník velkoplodý, chlorophyll fluorescence, gas exchange, heat phase, photochemical phase, photosystem I, photosystem II, 2, and 581
- Language:
- Multiple languages
- Description:
- Effects of root treatment with 5-aminolevulinic acid (ALA) on leaf photosynthesis in strawberry (Fragaria ananassa Duch.) plants were investigated by rapid chlorophyll fluorescence and modulated 820 nm reflection using 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) and methyl viologen (MV). Our results showed that ALA treatments increased the net photosynthetic rate and decreased the intercelluar CO2 concentration in strawberry leaves. Under DCMU treatment, trapping energy for QA reduction per PSII reaction center increased greatly, indicating DCMU inhibited electron transfer from QA−. The maximum photochemical efficiency of PSII (Fv/Fm) decreased under the DCMU treatment, while a higher Fv/Fm remained in the ALA-pretreated plants. Not only the parameters related to a photochemical phase, but also that one related to a heat phase remained lower after the ALA pretreatment, compared to the sole DCMU treatment. The MV treatment decreased PSI photochemical capacity. The results of modulated 820 nm reflection analysis showed that DCMU and MV treatments had low re-reduction of P700 and plastocyanin (PSI). However, the strawberry leaf discs pretreated with ALA exhibited high re-reduction of PSI under DCMU and MV treatments. The results of this study suggest that the improvement of photosynthesis by ALA in strawberry was not only related to PSII, but also to PSI and electron transfer chain., Y. P. Sun, J. Liu, R. X. Cao, Y. J. Huang, A. M. Hall, C. B. Guo, L. J. Wang., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Foliar anthocyanins in Pelargonium × hortorum are unable to alleviate light stress under photoinhibitory conditions
- Creator:
- Liakopoulos, G. and Spanorigas, I.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, anthocyanins, chlorophyll fluorescence, photoprotection, photosynthesis, photosystem II, 2, and 58
- Language:
- Multiple languages
- Description:
- Photosynthetic organs are often characterized by anthocyanins being accumulated either in the epidermal or in the mesophyll cells making these tissues to turn reddish-brown in colour. It has been hypothesized that these pigments protect underlying chloroplasts from light-stress because they absorb photons of the photosynthetically active waveband. However, the photoprotective role of anthocyanins has not been undoubtedly shown on a broad range of species. In this study, green and anthocyanic areas of leaves of Pelargonium × hortorum, the latter possessing variable levels of anthocyanins, were compared using pigment analysis and pulse amplitude modulated in vivo chlorophyll (Chl) fluorescence. Quenching analysis of the induction and dark relaxation curves of slow Chl fluorescence kinetics showed that at photoinhibitory conditions [by applying above-saturation light intensity of 1,600 μmol(quantum) m-2 s-1 white light at low (4°C) temperature], anthocyanic areas were at least equally sensitive to photoinhibition as green leaf areas. In fact, the level of photoinhibition tended to be proportional to the level of anthocyanin accumulation suggesting that this characteristic was indicative of the photoinhibitory risk. The results of the present study clearly show that anthocyanins in leaf areas of Pelargonium do not afford a photoprotective advantage., G. Liakopoulos, I. Spanorigas., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
5. Photoinhibition of Suaeda salsa to chilling stress is related to energy dissipation and water-water cycle
- Creator:
- Sui, N.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, brakická rostlinná společenstva, photosynthesis, halophytes, Shan-tung (Čína : provincie), antioxidant enzyme, chlorophyll fluorescence, halophyte, photosystem I, photosystem II, Suaeda salsa, Yellow river, 2, and 581
- Language:
- Multiple languages
- Description:
- To investigate the photoprotection of energy dissipation and water-water cycle, a C3 euhalophytic herb, Suaeda salsa L., was exposed either to chilling temperature (4°C) accompanied by moderate irradiance (600 μmol m-2 s-1) (CM) and/or to chilling temperature (4°C) accompanied by low irradiance (100 μmol m-2 s-1) (CL). During chilling stress, both the maximal photochemical efficiency of PSII (Fv/Fm) and the oxidizable P700 decreased in S. salsa leaves either under CM or CL, which indicated the severe photoinhibition. Relative to Fv/Fm, the oxidizable P700 decreased markedly under CL, which indicated that PSI was more sensitive to CL treatment than PSII. Initial fluorescence, number of closed PSII centers, and nonphotochemical quenching increased under CM, but more markedly under CL in S. salsa leaves. Activity of superoxide dismutase and ascorbate peroxidase was higher under CM than that under CL. The production of reactive oxygen species (ROS) decreased first and then increased under both treatments, but the content of O2.- and H2O2 was higher under CL than that under CM after 12 h of chilling stress. These results suggested that photoinhibition in S. salsa might be related to the accumulation of reactive oxygen species (ROS) induced by excess energy. The water-water cycle could not dissipate energy efficiently under CL, which caused the great accumulation of ROS., N. Sui., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
6. Physiological characterization of photosynthesis, chloroplast ultrastructure, and nutrient content in bracts and rosette leaves from Glaucium flavum
- Creator:
- Redondo-Gómez, S., Mateos-Naranjo, E., and Moreno, F. J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, cartenoids, chlorophyll content, chlorophyll fluorescence, photosystem II, and stomatal conductance
- Language:
- Multiple languages
- Description:
- Glaucium flavum is a biennial plant that bears a rosette of leaves, producing a flower stalk, bracteate monochasium, in its second year. The aims of this work were both to investigate the contribution of bracts to gas-exchange activities in this species and to compare this contribution to that of rosette leaves. In addition, we investigated the extent to which its responses can be explained by chloroplast ultrastructure, as well as the possible role of nutrient concentrations in the physiological responses of both leaf types. Gas exchange and plant characteristics regarding chlorophyll fluorescence were examined in a field experiment; we also determined leaf relative water content, tissue concentrations of photosynthetic pigments, chloroplast ultrastructure and nutrient contents. Although bracts indeed contributed to gas-exchange activities of G. flavum, rosette leaves showed higher values of net photosynthetic rate and stomatal conductance to CO2 for photosynthetic photon flux density above 200 μmol m-2 s-1. The incongruities in photosynthetic rates between bracts and leaves may be explained by the bigger chloroplasts of rosette leaves, which results in a larger membrane surface area. This agrees with the higher pigment concentrations and quantum efficiency of photosystem II values recorded as well for rosette leaves. On the other hand, bracts showed higher sodium concentrations, which could be a mechanism for salt tolerance of G. flavum. and S. Redondo-Gómez, E. Mateos-Naranjo, F. J. Moreno.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public