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Start Over Creator Tuba, Z.

1. Anatomical and eco-physiological changes in leaves of couch-grass (Elymus repens L.), a temperate loess grassland species, after 7 years growth under elevated CO2 concentration

Creator:
Engloner, A. I., Kovács, D., Balogh, J., and Tuba, Z.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
mesophyll, net photosynthetic rate, phloem, sclerenchyma, stomatal conductance, stomatal density, tracheary, transpiration rate, and water use efficiency
Language:
Multiple languages
Description:
Leaf anatomy and eco-physiology of Elymus repens, a temperate loess grassland species, were determined after seven years of exposure to 700 μmol (CO2) mol-1 (EC). EC treatment resulted in significant reduction of stomatal density on both surfaces of couch-grass leaves. Thickness of leaves and that of the sclerenchyma tissues between the vessels and the adaxial surfaces, the area of vascular bundle, and the volumes of phloem and tracheary increased at EC while abaxial epidermis and the sclerenchyma layer between the vessel and the abaxial surface were thicker at ambient CO2 concentration (AC). Stomatal conductance and transpiration rates were lower in EC, while net CO2 assimilation rate considerably increased at EC exposure. Contents of soluble sugars and starch were higher in EC-treated couch-grass leaves than in plants grown at AC. and A. I. Engloner ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Chamber series and space-scale analysis of CO2 gas-exchange in grassland vegetation: A novel approach

Creator:
Czóbel, Sz., Fóti , Sz., Balogh, J., Nagy, Z., Bartha, S., and Tuba, Z.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
canopy chamber, grassland, loess, sand, and stand CO2 measurements
Language:
Multiple languages
Description:
Significant part of our work was developing a new type of CO2 and H2O gas exchange chambers fit for measuring stand patches. Ground areas of six chambers (ranged between 0.044-4.531 m2) constituted a logarithmic series with doubling diameters from 7.5 to 240.0 cm. We demonstrate one of the first results for stand net ecosystem CO2 exchange (NEE) rates and temporal variability for two characteristic Central European grassland types: loess and sand. The measured mean NEE rates and their ranges in these grasslands were similar to values reported in other studies on temperate grasslands. We also dealt with the spatial scale dependence from ecophysiological point of view. Our chamber-series measurement was performed in a perennial ruderal weed association. The variability of CO2-assimilation of this weed vegetation showed clear spatial scale-dependence. We found the lowest variability of the vegetation photosynthesis at the small-middle scales. The results of spatial variability suggest the 0.2832 m2 patch size is the characteristic unit of the investigated weed association and there is a kind of synphysiological minimi-area with characteristic size for each vegetation type. and Sz. Czóbel ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Changes in chloroplast morphology of different parenchyma cells in leaves of Haberlea rhodopensis Friv. during desiccation and following rehydration

Creator:
Nagy-Déri, H., Péli, E. R., Georgieva, K., and Tuba, Z.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, chloroplast, dessication tolerance, homoiochlorophyllous, mesophyll, palisade parenchyma, and spongy parenchyma
Language:
Multiple languages
Description:
The size, shape, and number of chloroplasts in the palisade and spongy parenchyma layers of Haberlea rhodopensis leaves changed significantly during desiccation and following rehydration. The chloroplasts became smaller and more rounded during desiccation, and aggregated in the middle of the cell. The size and number of chloroplasts in the palisade parenchyma cells were higher than in spongy parenchyma. The good correlation observed between the size or number of chloroplasts and the cross-sectional area of mesophyll cells, the cross-sectional width of the leaf and its water content suggested that the palisade cells were more responsive to water availability than the spongy cells. Changes in chloroplast number during desiccation and rehydration process are characteristic features for desiccation-tolerant plants (especially in homoiochlorophyllous strategy). and H. Nagy-Déri ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Changes in effects of ozone exposure on growth, photosynthesis, and respiration of Ginkgo biloba in Shenyang urban area

Creator:
He, X.-Y., Fu, S.-L., Chen, W., Zhao, T.-H., Xu, S., and Tuba, Z.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carboxylation efficiency, chlorophyll, dark respiration, gas exchange, intercellular CO2 concentration, leaf area index, non-stomatal limitations, photorespiration, stomatal conductance, and transpiration rate
Language:
Multiple languages
Description:
An open-top chamber experiment was carried out from April through October 2006 to examine the effects of elevated (80 nmol mol-1) atmospheric O3 on Ginkgo biloba (4-years-old) in urban area. The air with ambient O3 (AA, ≈ 45 nmol mol-1) was used as control. The leaf mass and size, leaf area index, net photosynthetic rate (PN), apparent quantum yield, transpiration rate, and stomatal conductance were decreased by elevated O3 (EO) exposure. Visible foliar injury, which is light-brown flecks, was observed in the EO OTCs after 90 d of exposure. Carboxylation efficiency (ΦCO2) and photorespiration and dark respiration rates were enhanced by EO exposure in the first half of the season, but all of them turned to be lower than those of the AA control at the end of experiment. Stomata limitation of photosynthesis was significantly higher than control in the whole season (p<0.05). Chlorophyll (Chl) content was lower in EO variant than in the control and the difference became more and more apparent through the season. Hence the decrease in PN of G. biloba exposed to EO was the result of both stomatal and non-stomatal limitations. In the early season, the inhibition of photosynthesis was mainly caused by the stomatal limitation, and the earliest response was photoprotective down-regulation of photosynthesis but not photodamage. However, at the end of the season, the non-stomatal limiting factors such as decrease in Chl content, decrease in ΦCO2, and anti-oxidative enzyme activity became more important. and X.-Y. He ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

5. Comparison of CO2 and H2O fluxes over grassland vegetations measured by the eddy-covariance technique and by open system chamber

Creator:
Balogh, J., Nagy, Z., Fóti, Sz., Pintér, K., Czóbel, Sz., Péli, E. R., Acosta, M., Marek, M. V., Csintalan, Zs., and Tuba, Z.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
leaf area index
Language:
Multiple languages
Description:
Measurements of CO2 and H2O fluxes were carried out using two different techniques-eddy-covariance (EC) and open system gas exchange chamber (OC)-during two-years' period (2003-2004) at three different grassland sites. OC measurements were made during fourteen measurement campaigns. We found good agreement between the OC and EC CO2 flux values (n = 63, r 2 = 0.5323, OC FCO2 = -0.6408+0.9508 EC FCO2). The OC FH2O values were consistently lower than those measured by the EC technique, probably caused by the air stream difference inside and outside the chamber. Adjusting flow rate within the chamber to the natural conditions would be necessary in future OC measurements. In comparison with EC, the OC proved to be a good tool for gas exchange measurements in grassland ecosystems. and J. Balogh ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

6. Competition between Chenopodium album and Helianthus annuus as reflected ín photosynthesís and transpiration

Creator:
Szente, K., Tuba, Z., Nagy, Z., and Zs.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Interspecific competition between fat hen (Chenopodium album L.) and sunflower (Helianthus annuus L. NSH-33 hybrid) in pure and mixed stands of identical plant density (35 x 35 cm spacing) was studied in smáli plot field experiments under drought stress. Decrease in net photosynthetic rate (E^) due to interspecific competition was not statistically significant in either species in the first part of the growing season. During drought stress, however, significantly decreased in sunflower, while it hardly changed in C. album in the same (interspecific) competition situation. In pure stands, transpiration rate (E) was lower in C. album than in sunflower and this difference was more pronoímced in mixed stands. Consequently, C. album showed a very high water use efficiency (WUE) especially in the shade layer, which accounts for a larger part of the canopy in this species. By contrast, WUE in sunflower decreased, especially in the sun layer of the mixed stand. Interspecific competition reduced the total biomass more severely in sunflower than in C. album by the end of the growing season. The reduction was especially remarkable in the biomass of the reproductive organs. Reproductive effort expressed as reproductive allocation was higher in C. album than in sunflower. Hence the reproductive effort in sunflower and C. album in both intra- and interspecific competition seemed to be correlated with WUE, which is a prime characteristic of drought stress tolerance.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

7. Ecophysiological responses of different density maíze stands under drought stress and during recovery

Creator:
Nagy, Z., Tuba, Z., and Csintalan, Zs.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Net photosynthesis (Pn)> transpiration (£) and water use efficiency (WUE) responses to prolonged drought and subsequent recovery after rewatering were investigated in sun and shade leaves of two maize (Zea mays L. cv. Pioneer 3839 SC) stands with different plant density (6.2 and 10.8 plants per m^). Drought stress was induced by the very smáli amount of precipitation (60 mm) during the 57 d of the study period. was higher in both sun and shade leaves in the low density stand through the study period, presumably owing to higher degree of intraspecific competition in the denser stand. did not decrease under severe drought stress in the sun leaves of the two stands. WUE decreased in sun leaves in both stands. decreased most in the shade leaves of the high density stand, due to less available radiation in this stand. The higher degree of intraspecific competition might also contribute to this. The short- and long-term responses by the stands to irrigation differed greatly, as WUE decreased in the high density stand and increased in the low density stand. Thus was more strongly affected in the high density stand because of the higher degree of interactive drought stress and intraspecific competition concurrently with considerable loss of stomatal control of E.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

8. Enhanced water use efficiency in dry loess grassland species grown at elevated air CO2 concentration

Creator:
Szente, K., Nagy, Z., and Tuba, Z.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
acclimation, gas exchange, net photosynthetic rate, stomatal conductance, and transpiration rate
Language:
Multiple languages
Description:
Net CO2 assimilation rate (PN), stomatal conductance (gs), transpiration rate (E), and water use efficiency (WUE) in four perennial C3 species (grasses: Dactylis glomerata, Festuca rupicola, dicots: Filipendula vulgaris, Salvia nemorosa) grown for 231 d in open-top chambers at ambient (CA, 350 µmol mol-1) or elevated (CE, 700 µmol mol-1) CO2 concentrations were compared. When measured at CE, PN was significantly higher in CE plants of all four species than in the CA ones. The increase in PN was less prominent in the two grasses than in the two dicots. The E was significantly higher in the CE-grass F. rupicola and CE-dicot F. vulgaris than in the CA plants. There was no change in E owing to CE in the other grass and dicot. The gs in F. vulgaris and F. rupicola increased, while there was a decrease in D. glomerata and no change in S. nemorosa. WUE increased in all species grown in CE: four- to five-fold in the dicots and less than two-fold in the grasses. The increase in WUE was primarily due to an increase in PN and not to a decrease in E. and K. Szente, Z. Nagy, Z. Tuba.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

9. Modelling net photosynthetic rate of winter wheat in elevated air CO2 concentrations

Creator:
Harnos, N., Tuba, Z., and Szente, K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
acclimation, carotenoids, chlorophyll, intercellular CO2 concentration, leaf area, net photosynthetic rate, ribulose-1,5-bisphosphate carboxylase/oxygenase capacity, temperature, and Triticum aestivum
Language:
Multiple languages
Description:
Winter wheat plants were grown in open top chambers either at 365 µmol mol-1 (AC) or at 700 µmol mol-1 (EC) air CO2 concentrations. The photosynthetic response of flag leaves at the beginning of flowering and on four vertical leaf levels at the beginning of grain filling were measured. Net photosynthetic rates (PN) were higher at both developmental phases in plants grown at EC coupled with larger leaf area and photosynthetic pigment contents. The widely accepted Farquhar net photosynthesis model was parameterised and tested using several observed data. After parameterisation the test results corresponded satisfactorily with observed values under several environmental conditions. and N. Harnos, Z. Tuba, K. Szente.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

10. Modelling of carbon isotope discrimination by vegetation

Creator:
Hidy, D., Haszpra, L., Barcza, Z., Vermeulen, A., Tuba, Z., and Nagy, Z.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
atmospheric modelling, 13C, carbon flux data, carbon isotope discrimination, carbon stable isotopes, and discrimination
Language:
Multiple languages
Description:
The paper presents a simple box model simulating the temporal variation of atmospheric 13CO2 concentration, atmospheric CO2 mixing ratio and 13C content of plant material. The model is driven by observed meteorological and measured biosphere-atmosphere CO2 exchange data. The model was calibrated and validated using measurements from a Hungarian atmospheric monitoring station. The simulated atmospheric stable carbon isotope ratio data agreed well with the measured ratios considering both the magnitude and the seasonal dynamics. Observed deviations between the measured and simulated δ13Cair values were systematically negative in winters, while deviations were random in sign and smaller by an order of magnitude during periods when the vegetation was photosynthetically active. This difference, supported by a significant correlation between the deviation and modeled fossil fuel contributions to CO2 concentration, suggests the increased contribution of 13C-depleted fossil fuel CO2 from heating and the lower boundary layer heights during winter. and D. Hidy ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public