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4402. Seznam použitých zkratek
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- Multiple languages
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
4403. Shade effect alters leaf pigments and photosynthetic responses in Norway spruce (Picea abies L.) grown under field conditions
- Creator:
- Bertamini, M., Muthuchelian, K., and Nedunchezhian, N.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, diphenyl carbazide, donor side, electron transport, NH2OH, photosystems 1 and 2, polypeptides, and ribulose-1,5-bisphosphate carboxylase
- Language:
- Multiple languages
- Description:
- The contents of chlorophyll (Chl) and carotenoids (Car) per fresh mass were lower in shade needles than in sun needles. Ribulose-1,5-bisphosphate carboxylase (RuBPC) activity and contents of soluble proteins were also significantly lower in shade needles. In isolated thylakoids, a marked lower rate of whole chain and photosystem (PS) 2 activities were observed in shade needles. Smaller lower rate of PS1 activity was also observed in shade needles. The artificial exogenous electron donors, diphenyl carbazide (DPC) and NH2OH, significantly restored the loss of PS2 activity in shade needles. Similar results were obtained when Fv/Fm was evaluated by Chl fluorescence measurements. The marked lower rate of PS2 activity in shade needles was due to the lower contents of 47, 33, 28-25, 23, and 17 kDa polypeptides. This conclusion was confirmed by immunological studies showing that the content of the 33 kDa protein of the watersplitting complex was diminished significantly in shade needles. and M. Bertamini, K. Muthuchelian, N. Nedunchezhian.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4404. Shade mitigates photoinhibition and enhances water use efficiency in kiwifruit under drought
- Creator:
- Montanaro, G., Dichio, B., and Xiloyannis, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carbon gain, excessive radiation, photosynthesis, semi-arid condition, shade, stomatal limitation, and water use efficiency
- Language:
- Multiple languages
- Description:
- We tested the hypotheses that a reduction of incident light of 50 % over sun-acclimated leaves of water stressed kiwifruit (Actinidia deliciosa var. deliciosa) would (1) reduce stomatal limitations to carbon supply and (2) mitigate the inactivation of the primary photochemistry associated with photosystem (PS) II, thereby this increases carbon gain and water-use efficiency (WUE). Groups of field-grown vines were either shaded or left naturally exposed and subjected to progressive water stress in order to study moderately and severely droughted vines, while other groups were well irrigated. Daily variations in leaf gas exchange and midday chlorophyll (Chl) a fluorescence were determined once plants had -0.6 MPa (moderate stress) and -1.0 MPa pre-down leaf water potential (severe stress). Variations in Chl pigment content and specific leaf area (SLA) are also discussed. Results reveal that 50 % shade application maintained efficiency of PSII close to 0.8 even under severe drought so that to prevent its large decline (0.65) recorded in sunlit leaves. Under moderate stress level stomata behaviour dominated upon metabolic impairments of PSII. Reduction of irradiance increased WUE (15-20 %) in droughted vines, representing a valuable intervention to save photosynthetic apparatus and improve WUE in vines experiencing typical Mediterranean summer stresses. and G. Montanaro, B. Dichio, C. Xiloyannis.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4405. Shifts in photosynthetic responses to írradiance and temperature in Viola species
- Creator:
- Mishio, M.
- Format:
- Type:
- model:internalpart and TEXT
- Subject:
- chlorophyll, Viola keiskei, Viola hondoensis-, specific leaf mass, seasonal course of gas exchange, and dark respiration rate
- Language:
- Multiple languages
- Description:
- The steady-state photosynthetic irradiance and temperature responses of Viola hondoensis and V. keiskei (Violaceae) growing in proximity in their nati ve environment and under three levels of artificial shade of relative irradiance (RI) of 7, 20 and 50 % were investigated. The maximum photosynthetic rates and temperature optima under natural conditions were much higher in V. keiskei than in V. hondoensis, except when in leaves of V. keiskei chlorophyll was degraded due to autumn frosts. When grown under artificial shade, both species had higher temperature optima as RI decreased. Since leaves under the three RI conditions experienced a similar leaf temperature, it was concluded that the shifts in the temperature responses with RI resulted from acclimation to the varying irradiance. The higher temperature optima observed in V. keiskei under natural conditions were probably due to the fact that V. keiskei grew in more shady microhabitats than V. hondoensis.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4406. Shilov, A. E.: Metal complexes in biomimetic chemical reactions. N2 fixation in solution, activation and oxidation of alkanes, chemical models of photosynthesis
- Creator:
- Prášil, O.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- biochemical physics
- Language:
- Multiple languages
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4407. Shima, A., Ichahashi, M., Fujiwara, Y., Takebe, H. (ed ): Frontiers of photobiology
- Creator:
- Šesták, Z.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4408. Short- versus long-term effects of elevated CO2 on night-time respiration of needles of Scots pine (Pinus sylvestris L.)
- Creator:
- Jach, M. E. and Ceulemans, R.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carbon, C/N, direct and indirect effects, nitrogen, soluble sugars, starch, and specific leaf area
- Language:
- Multiple languages
- Description:
- Dark respiration rate in the night (R D) was measured in five-year-old Scots pine (Pinus sylvestris L.) trees grown for two years under ambient (AC) and elevated (AC + 400 µmol mol-1 = EC) CO2 concentrations in open top chambers. Two needle age classes (i.e., current-year and one-year-old) were measured at AC and EC in both AC- and EC-grown pines. Additionally different chemical characteristics were determined on the needles, such as nitrogen (N), carbon (C), starch, and soluble sugar concentrations as well as specific leaf area. The direct, short-term and indirect, long-term effects of EC on R D for the two needle age classes were examined. R D was expressed on a per needle area, needle mass, N, C, and C/N bases. Direct effects were only pronounced in the AC treatment where inhibition of R D was found at EC in both current- and one-year-old needles. Indirect effects were only significant in one-year-old needles where a decrease was found in the EC grown trees as compared with AC ones when R D was expressed per unit needle mass, C, or C/N. R D per unit needle area and needle N were not sensitive to long-term EC, in any needle age class. Long-term EC treatment also influenced the response of the two needle age classes. One-year-old needles from the EC treatment had significantly lower R D than current-year needles, but no such response was observed in the AC treatment. Our experiment re-emphasised the importance of expressing R D on different bases for a correct interpretation of the responses to EC. Moreover, we showed that different needle age classes can respond differently to a CO2 enrichment. and M. E. Jach, R. Ceulemans.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4409. Short-term chromium(VI) stress induces different photosynthetic responses in two duckweed species, Lemna gibba L. and Lemna minor L.
- Creator:
- Oláh, V., Lakatos, G., Bertók, C., Kanalas, P., Szöllösi, E., Kis, J., and Mészáros, I.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, chlorophyll fluorescence, Cr(VI), duckweed, electron transport rate, Lemna gibba, Lemna minor, nonphotochemical quenching, and rapid light curves
- Language:
- Multiple languages
- Description:
- Physiological responses of two duckweed species, Lemna gibba and Lemna minor, to hexavalent chromium [Cr(VI)] were studied in axenic cultures using short-term (48 h) treatments by K2Cr2O7 (0-200 μM). Chlorophyll (Chl) fluorescence parameters and photosynthetic pigment composition of plants were screened to determine the effects of Cr(VI) exposures. The two duckweed species exhibited different sensitivity in the applied Cr(VI) concentration range. Chl fluorescence parameters of dark-adapted and light-adapted plants and electron transport inducibility were more sensitive to Cr(VI) in L. minor than in L. gibba. We also found fundamental differences in quantum yield of regulated, Y(NPQ), and nonregulated, Y(NO), non-photochemical quenching between the two species. As Cr(VI) concentration increased in the growth medium, L. minor responded with considerable increase of Y(NPQ) with a parallel significant increase of Y(NO). By contrast, in L. gibba only 200 μM Cr(VI) in the growth medium resulted in elevation of Y(NPQ) while Y(NO) remained more or less constant within the regarding Cr(VI) concentration range during 48 h. Photosynthetic pigment content did not change considerably during the short-term Cr(VI) treatment but decrease of Chl a/b and increase of Car/Chl ratios were observed in good accordance with the changes in Chl fluorescence parameters. The data suggest that various duckweed species respond with different sensitivity to the same ambient concentrations of Cr(VI) in the growth medium, and presumably to other environmental stresses too, which may have an influence on their competitive relations when heavy metal pollution occurs in aquatic ecosystem. and V. Oláh ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4410. Short-term dynamics of stomatal response to sudden increase in CO2 concentration in maize supplied with different amounts of water
- Creator:
- Hladnik, J., Eler, K., Kržan, K., Pintar, M., and Vodnik, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- curve fitting, elevated CO2, stomatal dynamics, water potential, water vapour pressure deficit, and Zea mays
- Language:
- Multiple languages
- Description:
- Environmental factors that influence stomatal conductance (gs) interact through a complex network of signal transduction and have therefore highly interdependent effect. In the present study we examined how plant water status affects stomatal sensitivity to the change of CO2 concentration ([CO2]). We investigated the short-term dynamic of stomatal response to a sudden [CO2] increase (from 400 to 700 µmol(CO2) mol-1) in maize supplied with different amounts of water (resulting ψw = -0.35, -0.52 and -0.75 MPa). Gas exchange measurements were performed in short logging intervals and the response was monitored under two different levels of water vapour pressure deficit (VPD) of 1 and 2 kPa in order to observe the impact of air humidity. Generalized logistic curves were fitted to standardized stomatal response data, which enabled us to objectively estimate the level (relative decrease of g s) and the dynamics of the response. Soil water stress and high VPD significantly decreased relative stomatal closure in response to [CO2] rise, but simultaneously accelerated stomatal response to [CO2], as revealed by shorter half life (t1/2). VPD significantly affected the response of well-watered plants. In contrast, a fast stomatal reaction of water-deprived plants was predetermined by a low xylem water potential (ψw) of the leaf and the influence of air humidity was minor. and J. Hladnik ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public