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4772. The relationship between the soil water storage and water-use efficiency of seven energy crops
- Creator:
- Podlaski, S., Pietkiewicz, S., Chołuj, D., Horaczek, T., Wiśniewski, G., Gozdowski, D., and Kalaji, H. M.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- sucho, výměna plynu, výběrová kritéria, obsah vody v půdě, drought, gas exchange, selection criteria, soil water content, 2, and 581
- Language:
- Multiple languages
- Description:
- The aim of this work was to determine two types of photosynthetic water-use efficiency in order to examine their utility as selection criteria for tolerance of energy crops to soil water deficit. Furthermore, effects of crop cultivation on soil water content and storage were investigated. Seven energy crops were examined: miscanthus, prairie cordgrass, willow, thorn-free rose, Virginia mallow, Bohemian knotweed, and topinambour. The highest values of instantaneous (WUE) and intrinsic (WUEi) water-use efficiencies were found for miscanthus and prairie cordgrass. The reduction of WUE and/or WUEi was caused mainly by a rapid rise in the transpiration rate and a greater stomatal conductance, respectively. Principal component analysis showed that neither WUE nor WUEi could be recommended as universal selection criteria for the drought tolerance in different energy crops. The proper localization of soil with a good supply of water is most the important condition for energy crop plantations., S. Podlaski, S. Pietkiewicz, D. Chołuj, T. Horaczek, G. Wiśniewski, D. Gozdowski, H. M. Kalaji., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4773. The release of extrinsic polypeptides and manganese cluster from photosystem 2 membranes under high hydrostatic pressure
- Creator:
- Yu, Y., Tian, S.-M., Ruan, K.-C., and Xu, C.-H.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- oxygen evolution, spinach, and Spinacia oleracea
- Language:
- Multiple languages
- Description:
- Three extrinsic polypeptides and manganese cluster were sequentially released from the membrane when photosystem 2 (PS2) membranes were kept under high hydrostatic pressure. The 17 kDa polypeptide was the most sensitive, while the 33 kDa polypeptide was the most reluctant to the treatment with high pressure. The release of manganese was not simply correlated with the loss of 33 kDa polypeptide. The losing of oxygen-evolving activity of PS2 was synchronised with the releasing of extrinsic polypeptides and manganese. and Y. Yu ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4774. The residual effects of bensulfuron-methyl on growth and photosynthesis of soybean and peanut
- Creator:
- Su, W. C., Sun, L. L., Ge, Y. H., Wu, R. H., Xu, H. L., and Lu, C. T.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fytotoxicita, phytotoxicity, podzemnice olejná, chlorofylová fluorescence, výměna plynu, relativní obsah chlorofylu, Arachis hypogaea, chlorophyll fluorescence, gas exchange, Glycine max (Linn.) Merr., relative chlorophyll content, 2, and 581
- Language:
- Multiple languages
- Description:
- The effects of various concentrations of bensulfuron-methyl residues (BSM, 0-500 μg kg-1) on the growth and photosynthesis of soybean and peanut were studied. Shoot length, root length, root-to-shoot ratio, and biomass of soybean and peanut seedlings declined with the increase of BSM residue concentrations. As the concentration of BSM increased, SPAD value, net photosynthetic rate, stomatal limitation, stomatal conductance, and transpiration rate also declined with varying extent, but dark respiration rate and intercellular CO2 concentration increased gradually. PSII maximum quantum yield, actual quantum yield, and electron transport rate were significantly reduced by the BSM residues in soil, and the reduction was mostly attributed to the decrease in photochemical quenching coefficient. The results showed that photosynthesis in both crops was limited by nonstomatal factors. The residues of BSM caused reversible damage in PSII reaction centers and decrease the proportion of available excitation energy used for photochemistry., W. C. Su, L. L. Sun, Y. H. Ge, R. H. Wu, H. L. Xu, C. T. Lu., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4775. The response of spinach piants to excess of copper and cadmium
- Creator:
- Tukendorf, A.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Effects of excess Cd and Cu on the contents of total glutathione and phytochelatin (PC) were measured in roots and leaves of intact spinách piants. The total glutathione levels declined with the PCs synthesis. The kinetic data indicated that the shorter PCs were substrates for the longer PCs. PCs appear much earlier in roots than in leaves of intact spinách piants. The PC formation was stimulated most effectively by Cd, less so by Cu.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4776. The responses of photosynthetic rate and stomatal conductance of Fraxinus rhynchophylla to differences in CO2 concentration and soil moisture
- Creator:
- Zhang, S. Y., Zhang, G. C., Liu, X., and Xia, J. B.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, CO2 response, net photosynthetic rate, photorespiration, relative water content, soil moisture, 2, and 581
- Language:
- Multiple languages
- Description:
- The photosynthetic parameters in leaves of three-year-old seedlings of Fraxinus rhynchophylla L. were studied under different soil water conditions and CO2 concentrations ([CO2]) with a LI-COR 6400 portable photosynthesis system. The objective was to investigate the response of photosynthesis and stomatal conductance (gs) to various [CO2] and soil water conditions, and to understand the adaptability of F. rhynchophylla to such conditions. The results showed that the soil water content (RWC) required to maintain high photosynthetic productivity in F. rhynchophylla was 49.5-84.3%; in this range, net photosynthetic rate (PN) rose with [CO2] increasing from 500 to 1,400 μmol mol-1. Outside this RWC range, PN decreased significantly. The apparent maximum photosynthetic rate (Pmax,c) and carboxylation velocity (Vc) increased with increasing RWC and remained relatively high, when RWC was between 49.5 and 96.2%. CO2 compensation points and photorespiration rate exhibited a trend opposite to that of Pmax,c and Vc, indicating that moderate water stress was beneficial for increasing plant assimilation, decreasing photorespiration, and increasing production of photosynthates. gs declined significantly with increasing [CO2] under different water supplies, but the RWC range maintaining high gs increased. gs reached its maximum, when RWC was approximately 73% and then decreased with declining RWC. The maximal gs was found with increasing RWC. Thus, based on photosynthetic characteristics in artificial, vegetation construction in semiarid loess hill and gully area, F. rhynchophylla could be planted in habitats of low soil water content. and S. Y. Zhang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4777. The role of bicarbonate in the activity of photosystem 2
- Creator:
- van Rensen, J. J. S.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Photosystem 2 (PS 2) reaction centre can be considered as a water-plastoqninone oxido-reductase. Using four photons it transfers four electrons from two molecules of water to plastoquinone (PQ), producing the molecular oxygen and two molecules of double reduced PQ. PS 2 is the site of the antagonistic action of bicarbonate and formáte on PS 2 electron flow; incubation of isolated chloroplasts with formáte results in full inhibition of electron flow actívity, which can be restored by addition of bicarbonate. This bicarbonate effect is located at the Dl protein and affects the electron flow between the primary quinone and the PQ pool. Bicarbonate is probably involved in stabilizatíon of tíie semireduced secondary quinone Qb, and in the protonation reactions at this site. Under physiological conditions bicarbonate is boimd to thylakoid membranes. Addition of formáte to thylakoids appears to release CO2. The bicarbonate effect is not only observed in isolated chloroplasts, but also in intact organisms as green algae and leaves. Bicarbonate Controls PS 2 electron flow in order to cope with stress conditions leading to, for instance, photoinhibition or to the high rates of photorespiration.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4778. The role of oxygen in photosynthesis
- Creator:
- Vácha, F.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Oxygen can afFect the photosynthetic processes in two antagonistic (protective and destructive) ways. The protection is represented by draining off of the electron transport systém, by utilisation of NADPH and ATP, and production of carbon dioxide in the process of photorespiration, oxygen reduction in the Mehler reaction, and also by regeneration of monodehydroascorbate, one of the fmal products of the Mehler-peroxidase reaction. The subsequent building up of the proton gradient in the Mehler and Mehler-peroxidase reactions also helps protéct the photosynthetic apparatus. The production of harmful oxygen radicals is accompanied by the Mehler reaction. This is in contrast to the fact that the Mehler reaction can also protéct the photosynthetic apparatus. Nevertheless, the scavenging mechanisms in plants are efficient enough for protection against the active oxygen species. In some cases the disproportion between the production and scavenging of active oxygen can result in the destruction of thylakoid membrane. Singlet oxygen, another toxic form of oxygen, can also significantly increase the inhibition of photosynthesis in the presence of oxygen. None of these processes works alone or independently, they are in a dynamic equilibrium and each of them contributes to the regulation of photosynthesis.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4779. The role of photosynthetic activity in the regulation of flg22-induced local and systemic defence reaction in tomato
- Creator:
- Czékus, Z., Koprivanacz, P., Kukri, A., Iqbal, N., Ördög, A., and Poór, P.
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- assimilation, flagellin, mycotoxin, photosystem II, and stomatal conductance
- Language:
- Multiple languages
- Description:
- Flagellin (flg22) induces rapid and long-lasting defence responses. It may also affect the photosynthetic activity depending on several internal and external factors, such as the phytohormone ethylene or the day/night time. Based on the results, flg22 treatment, neither in the light phase nor in the evening, caused any significant change in chlorophyll fluorescence induction parameters in the leaves of wild-type and ethylene-receptor mutant Never ripe tomato plants measured the next morning. However, flg22 in the light phase decreased the effective quantum yield and the photochemical quenching both locally and systemically in guard cells. In parallel, the production of reactive oxygen species and nitric oxide increased, which contributed to the stomatal closure and a decrease in CO2 assimilation the next day. A decrease in sugar content and elevated hexokinase activity measured after flg22 exposure can also contribute to local defence responses in intact tomato plants.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4780. The salinity tolerance of freshwater cyanobacterium Synechococcus sp. PCC 7942 is determined by Its ability for osmotic adjustment and presence of osmolyte sucrose
- Creator:
- Ladas, N. P. and Papageorgiou, G. C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absorption spectra, cell doubling, chlorophyll content and fluorescence, cytoplasmic osmolality, glucose, NaCl, saccharose, and sugars
- Language:
- Multiple languages
- Description:
- We investigated the factors that impose an upper limit of salinity tolerance to the unicellular freshwater cyanobacterium Synechococcus sp. PCC 7942. Above approx. 0.4 M NaCl, Synechococcus cells cease to proliferate, after having accumulated 0.3 M sucrose. Cells that pre-accumulated sucrose could tolerate up to 0.5 M NaCl, but not 0.6 M NaCl. After exposure to 0.5 M NaCl or higher, the cells were irreversibly modified becoming unable for osmotic volume adjustments. and N. P. Ladas, G. C. Papageorgiou.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public