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2382. Effects of high temperature on chlorophyll fluorescence induction and the kinetics of far red radiation-induced relaxation of apparent F0 in maize leaves
- Creator:
- Jin, Ming-Xian, Li, De-Yao, and Mi, Hualing
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- heat stress and Zea mays L.
- Language:
- Multiple languages
- Description:
- Temperature dependence (25-50 °C) of chlorophyll (Chl) fluorescence induction, far-red radiation (FR)-induced relaxation of the post-irradiation transient increase in apparent F0, and the trans-thylakoid proton gradients (ΔpH) was examined in maize leaves. Temperatures above 30 °C caused an elevation of F0 level and an enhancement of F0 quenching during actinic irradiation. Millisecond delayed light emission (ms-DLE), which reflects the magnitude of ΔpH, decreased strikingly above 35 °C, and almost disappeared at 50 °C. It indicates that the heat-enhanced quenching of F0 under actinic irradiation could not be attributed mainly to the mechanism of ΔpH-dependent quenching. The relaxation of the post-irradiation transient increase in apparent F0 upon FR irradiation could be decomposed into two exponential components (τ1 = 0.7-1.8 s, τ2 = 2.0-9.9 s). Decay times of both components increased with temperature increasing from 25 to 40-45 °C. The bi-phasic kinetics of FR-induced relaxation of the post-irradiation transient increase in apparent F0 and its temperature dependence may be related to plastoquinone (PQ) compartmentation in the thylakoid membranes and its re-organisation at elevated temperature. and Ming-Xian Jin, De-Yao Li, Hualing Mi.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2383. Effects of humic acid on photosynthetic efficiency of rapeseed plants growing under different watering conditions
- Creator:
- Lotfi, R., Kalaji, H. M., Valizadeh, G. R., Khalilvand Behrozyar, E., Hemati, A., Gharavi-Kochebagh, P., and Ghassemi, A.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorofyl, fluorescence, fotosyntéza, chlorophyll, photosynthesis, water stress, 2, and 581
- Language:
- Multiple languages
- Description:
- Water is a limited resource and is likely to become even more restricted with climate change. The aim of this study was to evaluate the effect of humic acid (HA) applications on photosynthesis efficiency of rapeseed plants under different watering conditions. Water stress strongly increased electron transport flux, probability that trapped excitation can move an electron into the electron transport chain beyond QA, and quantum yield of reduction of end electron acceptors at the PSI acceptor side. Application of HA decreased the values of these parameters to be similar to those of non-stress conditions. We found that, the application of HA improved plants net photosynthesis under water stress via increasing the rate of gas exchange and electron transport flux in plants., R. Lotfi, H. M. Kalaji, G. R. Valizadeh, E. Khalilvand Behrozyar, A. Hemati, P. Gharavi-Kochebagh, A. Ghassemi., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2384. Effects of hypo- and hypersalinity on photosynthetic performance of Sargassum fusiforme (Fucales, Heterokontophyta)
- Creator:
- Xie, X. J., Wang, X. L., Lin, L. D., He, L. W., Gu, W. H., Gao, S., Yan, X. F., Pan, G. H., Wu, M. J., and Wang, G. C.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- photosynthesis, aquaculture, chlorophyll a fluorescence, dithiothreitol, rapid light curve, violaxanthin, 2, and 581
- Language:
- Multiple languages
- Description:
- Photoprotection mechanisms protect photosynthetic organisms, especially under stress conditions, against photodamage that may inhibit photosynthesis. We investigated the effects of short-term immersion in hypo- and hypersalinity sea water on the photosynthesis and xanthophyll cycle in Sargassum fusiforme (Harvey) Setchell. The results indicated that under moderate light [110 μmol(photon) m-2 s-1], the effective quantum yield of PSII was not reduced in S. fusiforme fronds after 1 h in hyposalinity conditions, even in fresh water, but it was significantly affected by extreme hypersalinity treatment (90‰ sea water). Under high light [HL, 800 μmol(photon) m-2 s-1], photoprotective mechanisms operated efficiently in fronds immersed in fresh water as indicated by high reversible nonphotochemical quenching of chlorophyll fluorescence (NPQ) and de-epoxidation state; the quantum yield of PSII recovered during the subsequent relaxation period. In contrast, fronds immersed in 90‰ sea water did not withstand HL, barely developed reversible NPQ, and accumulated little antheraxanthin and zeaxanthin during HL, while recovery of the quantum yield of PSII was severely inhibited during the subsequent relaxation period. The data provided concrete evidence supporting the short-term tolerance of S. fusiforme to immersion in fresh water compared to hypersalinity conditions. The potential practical implications of these results were also discussed., X. J. Xie, X. L. Wang, L. D. Lin, L. W. He, W. H. Gu, S. Gao, X. F. Yan, G. H. Pan, M. J. Wu, G. C. Wang., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2385. Effects of inorganic nitrogen availability on the sporophytes of Acrostichum aureum L.
- Creator:
- Pillai, R. S. and Ong, B.-L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, fern, fertilization, growth, and photosynthesis
- Language:
- Multiple languages
- Description:
- Plants grown at low irradiance were fertilized with 0, 60, and 600 g m-3 NH4NO3 once every fortnight. Plants treated with high N concentrations showed an increased growth, producing longer and broader fronds with larger areas, and were darker green in colour. Nitrogen also increased the content of chlorophyll (Chl) and carotenoids per leaf area unit. Different N treatments did not affect the photosynthetic efficiency of photosystem 2, as reflected by the high values of Chl fluorescence kinetics Fv/Fm, ranging between 0.81 to 0.84, and Fv/F0 of 4.30 to 5.10. An increase in photochemical quenching (qP), accompanied by a decrease in non-photochemical quenching (qN), was observed in sporophytes fertilized with increased concentrations of NH4NO3. Nitrogen availability allowed sporophytes of Acrostichum aureum to become more established under natural conditions. and R. S. Pillai, B.-L. Ong.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2386. Effects of irradiance on growth, photosynthetic characteristics, and artemisinin content of Artemisia annua L.
- Creator:
- Wang, M. L., Jiang, Y. S., Wei, J. Q., Wei, X., Qi, X. X., Jiang, S. Y. , and Wang, Z. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- biomass allocation, diameter, growth, root, and seasonal course
- Language:
- Multiple languages
- Description:
- With an increase in growth irradiance (from 15 to 100 % of full sunlight, I15 to I100), the maximum net photosynthetic rate (Pmax), compensation (CI) and saturation irradiances of A. annua increased. At full sunlight, A. annua had a high capacity of photosynthesis, while at low irradiance it maintained a relatively high Pmax with a low CI. The height and diameter growth, total and leaf biomass, and artemisinin content of A. annua decreased with the decrease in irradiance, which might be connected with lower photosynthesis at lower than at higher irradiance. Irradiances changed biomass allocations of A. annua. The leaf/total mass ratio of A. annua increased with decreasing irradiance, but the root/total mass ratio and root/above-ground mass generally increased with increasing irradiance. Thus A. annua can grow in both weak and full sunlight. However, high yield of biomass and artemisinin require cultivation in an open habitat with adequate sunshine. and M. L. Wang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2387. Effects of irradiance on photosynthetic characteristics and growth of Mosla chinensis and M. scabra
- Creator:
- Liao, J.-X., Ge, Y., Huang, C.-C., Zhang, J., Liu, Q.-X., and Chang, J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- biomass accumulation, compensation and saturation irradiance, concomitant species, leaf area ratio, net photosynthetic rate, plasticity, specific leat area, and water use efficiency
- Language:
- Multiple languages
- Description:
- Photosynthetic and growth characteristics of Mosla chinensis and M. scabra were compared at three irradiances similar to shaded forest understory, forest edge, and open land. At 25 % full ambient irradiance, M. chinensis and M. scabra had similar photosynthetic characteristics, but saturation irradiance, compensation irradiance, and apparent quantum yield of M. chinensis were higher than those of M. scabra at full ambient irradiance and 70 % full ambient irradiance. At the same irradiance treatment, specific leaf area and leaf area ratio of M. chinensis were lower than those of M. scabra. Photon-saturated photosynthetic rate and water use efficiency of M. chinensis, however, were not significantly higher than those of M. scabra, and the leaf area and total biomass were lower than those of M. scabra. As a sun-acclimated plant, the not enough high photosynthetic capacity and lower biomass accumulation may cause that M. chinensis has weak capability to extend its population and hence be concomitant in the community. and J.-X. Liao ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2388. Effects of irradiance-sulphur interactions on enzymes of carbon, nitrogen, and sulphur metabolism in maize plants
- Creator:
- Astolfi, S., de Biasi, M. G., and Passera, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- o-acetylserine sulphydrylase, ATP sulphurylase, chlorophyll, dry mass, glutamine synthetase, NAD-dependent glutamate dehydrogenase, nitrate reductase, phosphoenolpyruvate carboxylase, proteins, and ribulose-1,5-bisphosphate carboxylase
- Language:
- Multiple languages
- Description:
- The effect of sulphur deprivation and irradiance (180 and 750 µmol m-2 s-1) on plant growth and enzyme activities of carbon, nitrogen, and sulphur metabolism were studied in maize (Zea mays L. Pioneer cv. Latina) plants over a 15-d-period of growth. Increase in irradiance resulted in an enhancement of several enzyme activities and generally accelerated the development of S deficiency. ATP sulphurylase (ATPs; EC 2.7.7.4) and o-acetylserine sulphydrylase (OASs; EC 4.2.99.8) showed a particular and different pattern as both enzymes exhibited maximum activity after 10 d from the beginning of deprivation period. Hence in maize leaves the enzymes of C, N, and S metabolism were differently regulated during the leaf development by irradiance and sulphur starvation. and S. Astolfi, M. G. de Biasi, C. Passera.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2389. Effects of leaf-to-fruit ratio on chlorophyll fluorescence parameters of walnut (Juglans regia L.) leaves
- Creator:
- Zhang, C. F., Pan, C. D., and Chen, H.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- defoliace, ovocné stromy, defoliation, fruit trees, photochemical efficiency of PSII, 2, and 581
- Language:
- Multiple languages
- Description:
- In this study, we investigated maximal quantum yield of PSII photochemistry(Fv/Fm),effective quantum yield of PSII photochemistry (ΦPSII), and nonphotochemical quenching (NPQ) of walnut (Juglans regia ‘Xinxin2’) leaves with different leaf-to-fruit ratios (LFRs). The results indicated that the increasing LFR increased the values of Fv/Fm, ΦPSII, and NPQ in leaves on the girdled shoot with one and two leaves, and decreased the values of Fv/Fm and ΦPSII in leaves on the girdled shoot with five leaves, whereas had no effect on the chlorophyll (Chl) fluorescence in leaves on the girdled shoot with three and four leaves. These results indicate that the effects of LFR on Chl fluorescence depend on a LFR range and show a transitional trend transition, and that excessive fruit load accelerates leaf senescence resulting in the destruction of the reaction center in PSII., C. F. Zhang, C. D. Pan, H. Chen., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2390. Effects of light intensity and temperature on the photosynthetic irradiance response curves and chlorophyll fluorescence in three picocyanobacterial strains of Synechococcus
- Creator:
- Jodłowska, S. and Śliwińska, S.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, fluorescence, teplota, photosynthesis, temperature, irradiance, photoacclimation, picocyanobacteria, 2, and 581
- Language:
- Multiple languages
- Description:
- Chrococcoid cyanobacteria of the genus Synechococcus are the important component of marine and freshwater ecosystems. Picocyanobacteria comprise even 80% of total cyanobacterial biomass and contribute to 50% of total primary cyanobacterial bloom production. Chlorophyll (Chl) fluorescence and photosynthetic light response (P-I) curves are commonly used to characterize photoacclimation of Synechococcus strains. Three brackish, picocyanobacterial strains of Synechococcus (BA-132, BA-124, BA-120) were studied. They were grown under 4 irradiances [10, 55, 100, and 145 μmol(photon) m-2 s-1] and at 3 temperatures (15, 22.5, and 30°C). Photosynthetic rate was measured by Clark oxygen electrode, whereas the Chl fluorescence was measured using Pulse Amplitude Modulation fluorometer. Based on P-I, two mechanisms of photoacclimation were recognized in Synechococcus. The maximum value of maximum rate of photosynthesis (Pmax) expressed per biomass unit at 10 μmol(photon) m-2 s-1 indicated a change in the number of photosynthetic units (PSU). The constant values of initial slope of photosynthetic light response curve (α) and the maximum value of Pmax expressed per Chl unit at 145 μmol(photon) m-2 s-1 indicated another mechanism, i.e. a change in PSU size. These two mechanisms caused changes in photosynthetic rate and its parameters (compensation point, α, saturation irradiance, dark respiration, Pmax) upon the influence of different irradiance and temperature. High irradiance had a negative effect on fluorescence parameters, such as the maximum quantum yield and effective quantum yield of PSII photochemistry (φPSII), but it was higher in case of φPSII., S. Jodłowska, S. Śliwińska., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public