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2302. Significance of mesophyll conductance for photosynthetic capacity and water-use efficiency in response to alkaline stress in Populus cathayana seedlings

Creator:
Xu, G., Huang, T. F., Zhang, X. L., and Duan, B. L.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, photosynthesis, carbon isotope discrimination, chloroplast CO2 concentration, curve-fitting method, gas exchange, intercellular CO2 concentration, leaf nitrogen, specific leaf area, stomatal conductance, 2, and 581
Language:
Multiple languages
Description:
Cuttings of Populus cathayana were exposed to three different alkaline regimes (0, 75, and 150 mM Na2CO3) in a semicontrolled environment. The net photosynthesis rate (PN), mesophyll conductance (gm), the relative limitations posed by stomatal conductance (Ls) and by mesophyll conductance (Lm), photosynthetic nitrogen-use efficiency (PNUE), carbon isotope composition (δ13C), as well as specific leaf area (SLA) were measured. PN decreased due to alkaline stress by an average of 25% and gm decreased by an average of 57%. Alkaline stress caused an increase of Lm but not Ls, with average Ls of 26%, and Lm average of 38% under stress conditions. Our results suggested reduced assimilation rate under alkaline stress through decreased mesophyll conductance in P. cathayana. Moreover, alkaline stress increased significantly δ13C and it drew down CO2 concentration from the substomatal cavities to the sites of carboxylation (Ci-Cc), but decreased PNUE. Furthermore, a relationship was found between PNUE and Ci-Cc. Meanwhile, no correlation was found between δ13C and Ci/Ca, but a strong correlation was proved between δ13C and Cc/Ca, indicating that mesophyll conductance was also influencing the 13C/12C ratio of leaf under alkaline stress. and G. Xu ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2303. Significance of the leaf area ratio in Hevea brasiliensis under high irradiance and low temperature stress

Creator:
Ray, D., Dey, S. K., and Das, G.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
CO2 concentration in sub-stomatal spaces, net photosynthetic rate, Paraquat, photo-oxidative damage, and stomatal conductance
Language:
Multiple languages
Description:
Adjustment in leaf area : mass ratio called leaf area ratio (LAR) is one of the strategies to optimize photon harvesting. LAR was recorded for 10 genotypes of Hevea brasiliensis under high irradiance and low temperature and the genotypes were categorized into two groups, i.e. high LAR and low LAR types. Simultaneously, the growth during summer as well as winter periods, photosynthetic characteristics, and in-vitro oxidative damage were studied. Low LAR (19.86±0.52 m2 kg-1) types, recorded an average of 18.0 % chlorophyll (Chl) degradation under high irradiance and 7.1 % Chl degradation under low temperature. These genotypes maintained significantly higher net photosynthetic rate (PN) of 10.4 μmol(CO2) m-2 s-1 during winter season. On the contrary, the high LAR (24.33±0.27 m2 kg-1) types recorded significantly lower PN of 4 μmol(CO2) m-2 s-1 and greater Chl degradation of 37.7 and 13.9 % under high irradiance and low temperature stress, respectively. Thus LAR may be one of the physiological traits, which are possibly involved in plant acclimation process under both stresses studied. and D. Ray, S. K. Dey, G. Gas.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2304. Silicon nutrition mitigates salinity stress in maize by modulating ion accumulation, photosynthesis, and antioxidants

Creator:
Khan, W. U. D., Aziz, T., Maqsood, M. A., Farooq, M., Abdullah, Y., Ramzani, P. M. A., and Bilal, H. M.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
chlorofyl, chlorophyll, photosynthetic rate, total phenolics, 2, and 581
Language:
Multiple languages
Description:
Silicon is known to improve resistance against salinity stress in maize crop. This study was conducted to evaluate the influence of silicon application on growth and salt resistance in maize. Seeds of two maize genotypes (salt-sensitive ‘EV 1089’ and salt-tolerant ‘Syngenta 8441’) were grown in pots containing 0 and 2 mM Si with and without 50 mM NaCl. After detailed investigation of ion concentrations in different maize organs, both genotypes were further selected in hydroponic experiment on basis of their contrasting response to salinity stress. In the second experiment, pre-germinated seedlings were transplanted into nutrient solution with 0 and 60 mM NaCl with and without 2 mM Si. Both genotypes differed significantly in their response to salinity. Silicon addition alleviated both osmotic and oxidative stress in maize crop by improving the performance of defensive machinery under salinity stress. Silicon application also improved the water-use efficiency in both tested genotypes under both normal and salinity stress conditions. In conclusion, this study implies that the silicon-treated maize plants had better chance to survive under salinity conditions and their photosynthetic and biochemical apparatus was working far better than that of silicon-non-treated plants., W. U. D. Khan, T. Aziz, M. A. Maqsood, M. Farooq, Y. Abdullah, P. M. A. Ramzani, H. M. Bilal., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2305. Similar effects of ozone on four cultivars of lettuce in open top chambers during winter

Creator:
Calatayud, A., Alvarado, J. W., and Barreno, E.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, Lactuca sativa, lipid peroxidation, malondialdehyde, and root length
Language:
Multiple languages
Description:
Ozone is the major phytotoxic air pollutant that reduces the yield of several agricultural crops in the Spanish Mediterranean area. We studied four lettuce cultivars (Lactuca sativa L.) for the effects of different O3 concentrations during the winter on chlorophyll (Chl) a fluorescence, lipid peroxidation, and root length in outdoor open-top chambers. Under O3 the photosynthetic quantum conversion declined while heat emissions increased in all cultivars; these results provide more evidence of non-filtered air with additional ozone (NFA+O3) treatment compared with non-filtered air (NFA) and charcoal filtered ozone-free air (CFA). Changes in the Chl a fluorescence may be associated with an increase in membrane lipid peroxidation as well as with observed reduction of root length under O3 stress. and A. Calatayud, J. W. Alvarado, E. Barreno.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2306. Similar susceptibility to excess irradiance in sun and shade acclimated saplings of Norway spruce [Picea abies (L.) Karst.] and stone pine (Pinus cembra L.)

Creator:
Gamper, R., Mayr, S., and Bauer, H.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, frost hardening, low temperature, and net photosynthetic rate
Language:
Multiple languages
Description:
We compared the responses of sun and shade acclimated saplings of Picea abies and Pinus cembra to excess photosynthetic photon flux density (PPFD) equivalently exceeding the level for saturating net photosynthetic rate (PN). Exposure for 2 h up to 2000 µmol(photon) m-2 s-1 did not affect radiant energy saturated PN. Photoinhibition of photosynthesis was indicated by a small (10 %) reduction of the potential efficiency of photosystem 2 as derived from measurements of chlorophyll fluorescence (FV/FM). However, the extent of FV/FM reduction and half-time for recovery were similar in sun and shade acclimated saplings of both species. Furthermore, the effect on FV/FM was not stronger when the plants were exposed to excess PPFD at 5 °C instead of 15 °C. Frost-hardening of plants increased slightly their resistance to excess PPFD. Establishment of these conifer saplings usually acclimated to shade in their natural habitat may hardly be endangered by a sudden increase of PPFD, e.g., by gap formation. and R. Gamper, S. Mayr, H. Bauer.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2307. Simple and accurate allometric model for leaf area estimation in Vitis vinifera L. genotypes

Creator:
Buttaro, D., Rouphael, Y., Rivera, C. M., Colla, G., and Gonnella , M.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
estimation model, linear regression, and nondestructive method
Language:
Multiple languages
Description:
The aim of the present experiment was to evaluate the currently used allometric models for Vitis vinifera L., as well as to develop a simple and accurate model using linear measurements [leaf length (L.) and leaf width (W)] for estimating the individual leaf area (LA) of nine grapevine genotypes. For model construction, a total of 1,630 leaves coming from eight genotypes in 2010 was sampled during different leaf developmental stages and encompassed the full spectrum of leaf sizes. The model with single measurement of L could be considered an interesting option because it requires measurement of only one variable, but at the expense of accuracy. To find a model to estimate individual LA accurately for grapevine plants of all genotypes, both measurements of L and W should be involved. The proposed linear model [LA = 0,465 + 0,914 (L x W)] was adopted for its accuracy: the highest coefficient of determination (>0,98), the smallest mean square error, the smallest prediction sum of squares, and the reasonable close prediction sum of squares value to error sum of squares. To validate the LW model, an independent data set of 200 leaves coming from another genotype in 2011 was used. Correlation coefficients showed that there was a highly reliable relationships between predicted leaf area and the observed leaf area, giving an overestimation of 0.8% in the prediction. and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2308. Simulation of PSII-operating efficiency from chlorophyll fluorescence in response to light and temperature in chrysanthemum (Dendranthema grandiflora) using a multilayer leaf model

Creator:
Janka, E., Körner, O, Rosenqvist, E., and Ottosen, C.-O.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
skleníky, fotosyntéza, greenhouses, photosynthesis, extrémní klima, extreme climate, monitor, paradermal layer, 2, and 581
Language:
Multiple languages
Description:
Chlorophyll fluorescence serves as a proxy photosynthesis measure under different climatic conditions. The objective of the study was to predict PSII quantum yield using greenhouse microclimate data to monitor plant conditions under various climates. Multilayer leaf model was applied to model fluorescence emission from actinic light-adapted (F') leaves, maximum fluorescence from light-adapted (Fm') leaves, PSII-operating efficiency (Fq'/Fm'), and electron transport rate (ETR). A linear function was used to approximate F' from several measurements under constant and variable light conditions. Model performance was evaluated by comparing the differences between the root mean square error (RMSE) and mean square error (MSE) of observed and predicted values. The model exhibited predictive success for Fq'/Fm' and ETR under different temperature and light conditions with lower RMSE and MSE. However, prediction of F' and Fm' was poor due to a weak relationship under constant (R2 = 0.48) and variable (R2 = 0.35) light., E. Janka, O. Körner, E. Rosenqvist, C.-O. Ottosen., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2309. Simulation of Pulse-Amplitude-Modulated (PAM) fluorescence: Limitations of some PAM-parameters in studying environmental stress effects

Creator:
Juneau, P., Green, B. R., and Harrison, P. J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
copper, Chlamydomonas, non-quenched fluorescence, parameter calculation, and photochemical quenching
Language:
Multiple languages
Description:
Fluorescence parameters obtained during steady-state electron transport are frequently used to evaluate photosynthetic efficiency of plants. We studied the behaviour of those parameters as a function of irradiance-adapted fluorescence yields FS and F'M. Applied simulations showed that photochemical quenching evaluated by qP is greatly influenced by the steady-state fluorescence level (FS), and that its evolution is not complementary to non-photochemical quenching (qN). On the other hand, the relative photochemical and non-photochemical quenching coefficients (qP(rel) and qN(rel)) proposed by Buschmann (1995) represent better the balance between the energy dissipation pathways. However, these relative parameters are also non-linearly related when the FS level is varied. We investigated the application of a new parameter, the relative unquenched fluorescence (UQF(rel)) which takes into account the fraction of non-quenched fluorescence yield (FS), which is related to closed photosystem 2 reaction centres not participating in electron transport. By using computer simulations and real in vivo measurements, we found that this new parameter is complementary to qP(rel) and qN(rel), which may facilitate the use of PAM fluorescence as diagnostic tool in environmental studies. and P. Juneau, B. R. Green, P. J. Harrison.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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