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2042. Photosynthesis in two wheat cultivars differing in salt susceptibility
- Creator:
- El-Shintinawy, F.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- cultivar differences, ethylene, fatty acids, fluorescence emission spectra, polyamines, proline, putrescine, salinity, spermine, and spermidine
- Language:
- Multiple languages
- Description:
- Salinised (150 mM NaCl for 15 d) roots excised from salt sensitive wheat cultivar Giza 163 showed about 15-fold increase in the ratio of Na/K while salt tolerant Sakha 92 exhibited only 7.5-fold increase compared to their control ratios. Root ratio of saturated/unsaturated fatty acids was stimulated twice in the sensitive cultivar versus 1.7-fold increase in the tolerant ones. Salinity enhanced greatly the accumulation of spermine (Spm) and spermidine (Spd) contents associated with a decrease in putrescine (Put) content in both wheat cultivars. Higher ratios of Spm+Spd/Put associated with lower content of proline and low ethylene evolution were detected in shoots and roots of salt tolerant cultivar. Chlorophyll a/b ratio showed an increase from 1.3 in control of both cultivars to 1.6 and 1.4 in stressed Giza 163 and Sakha 92, respectively. A reduced Hill reaction activity (19 %) was observed in stressed chloroplasts isolated from leaves of the tolerant cultivar versus 40 % inhibition in the sensitive ones. Moreover, chloroplasts isolated from stressed leaves of the sensitive cultivar showed about 25 % reduction in fluorescence emission at 685 nm as well as shifts in the peaks in the visible region.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2043. Photosynthesis inhibition during gas exchange oscillations in ABA-treated Helianthus annuus: relative role of stomatal patchiness and leaf carboxylation capacity
- Creator:
- Šantrůček, J., Hronková, M., Květoň, J., and Sage, R. F.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- abscisic acid, CO2 response, cuticular conductance, stomatal conductance, sunflower, and transpiration
- Language:
- Multiple languages
- Description:
- Environmental factors that induce spatial heterogeneity of stomatal conductance, gs, called stomatal patchiness, also reduce the photochemical capacity of CO2 fixation, yet current methods cannot distinguish between the relative effect of stomatal patchiness and biochemical limitations on photosynthetic capacity. We evaluate effects of stomatal patchiness and the biochemical capacity of CO2 fixation on the sensitivity of net photosynthetic rate (PN) to stomatal conductance (gs), θ (θ = δP N/gs). A qualitative model shows that stomatal patchiness increases the sensitivity θ while reduced biochemical capacity of CO2 fixation lowers θ. We used this feature to distinguish between stomatal patchiness and mesophyll impairments in the photochemistry of CO2 fixation. We compared gas exchange of sunflower (Helianthus annuus L.) plants grown in a growth chamber and fed abscisic acid, ABA (10-5 M), for 10 d with control plants (-ABA). PN and gs oscillated more frequently in ABA-treated than in control plants when the leaves were placed into the leaf chamber and exposed to a dry atmosphere. When compared with the initial CO2 response measured at the beginning of the treatment (day zero), both ABA and control leaves showed reduced PN at particular sub-stomatal CO2 concentration (ci) during the oscillations. A lower reduction of P N at particular g s indicated overestimation of ci due to stomatal patchiness and/or omitted cuticular conductance, gc. The initial period of damp oscillation was characterised by inhibition of chloroplast processes while stomatal patchiness prevailed at the steady state of gas exchange. The sensitivity θ remained at the original pre-treatment values at high gs in both ABA and control plants. At low gs, θ decreased in ABA-treated plants indicating an ABA-induced impairment of chloroplast processes. In control plants, gc neglected in the calculation of gs was the likely reason for apparent depression of photosynthesis at low gs. and J. Šantrůček ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2044. Photosynthesis of a temperate fallow C3 herbaceous ecosystem: measurements and model simulations at the leaf and canopy levels
- Creator:
- Gouasmi, M., Mordelet, P., Demarez, V., Gastellu-Etchegorry, J.-P., Le Dantec, V., Dedieu, G., Menaut, J.-C., Calvet, J.-C., and Lamaze, T.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- photosynthesis
- Language:
- Multiple languages
- Description:
- The objectives of the study were to characterize photosynthesis of temperate fallow C3 herbaceous species and examine the performance of a simple photosynthesis model (based on the Farquhar's equations) to simulate carbon fluxes at the leaf and canopy levels. The maximum rate of carboxylation at 25°C (V m0) was estimated for sunlit leaves using in situ gas exchange data under saturating irradiance. Throughout the seasons, leaf measurements indicate that values of V m0 were similar for the four major species of the fallow. The rate declined from March (100 µmol m-2 s-1) to July (50 µmol m-2 s-1) and remained almost constant until November. The maximum quantum yield estimated for Potentilla reptans L. (dominant species) was 0.082 mol(CO2) mol-1(photon absorbed), similar to values already published for C3 species. Leaf area index (LAI) increased from winter (less than 0.2 m2 m-2) to spring (up to 4 m2 m-2). Rates of canopy photosynthesis (measured with a canopy chamber) strongly depended on LAI and temperature, in addition to irradiance. They reached a maximum of 25 µmol m-2 s-1 and were intermediate between those published for C4 grassland or cultivated species, and on woody species. At leaf level, simulations gave realistic predictions. At canopy level, the model had the ability to reproduce the effects of environmental and seasonal conditions. However, simulations underestimated the photosynthetic activity of the fallow canopy. and M. Gouasmi ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2045. Photosynthesis of a yellow-green mutant line in maize
- Creator:
- Zhong, X. M., Sun, S. F., Li, F. H., Wang, J., and Shi, Z. S.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, gene mutation, photochemical reaction, potential productivity, 2, and 581
- Language:
- Multiple languages
- Description:
- This study compared the relationship between chlorophyll (Chl) content, gas exchange, Chl fluorescence characteristics, and leaf color, using paired near-isogenic lines (NILs) of a medium-green leaf inbred line SN12 and a yellow-green leaf mutant SN62 to explore the photosynthesis of the yellow-green mutant. The SN62 was found in a female parent, Xianyu 335, which grew normally, although there were small yellow spots on the leaves at the seedling stage and yellow-green leaves appeared from the seedling to the maturation stage. The results indicated that Chl a (b), quantum efficiency of PSII, and maximal quantum yield of PSII photochemistry of SN62 were significantly lower than those of SN12, but there were almost no differences in the net photosynthetic rate (P N). There was no significant correlation between Chl a (b) and P N of inbred lines with different leaf colors. In the reproductive stage, photochemical quenching, effective quantum yield of PSII photochemistry, and the electron transport rate of SN62 increased obviously, and all parameter values exceeded the values of SN12. It explained that increasing the openness of the PSII reaction center was able to compensate for the lower Chl content, which was beneficial for harvesting more light energy for photochemical reactions. It also ensured that P N was not reduced., X. M. Zhong, S. F. Sun, F. H. Li, J. Wang, Z. S. Shi., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2046. Photosynthesis of cassava and its relation to crop productivity
- Creator:
- El-Sharkawy, M. A., De Tafur, S. M., and Cadavid, L. F.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Irrespective of the originál habitat of cassava {Manihot esculenta Crantz) cultivars, net photosynthetic rate (P^) was substantially reduced in leaves developed in a cool climate as compared with warm-climate leaves. Cool-climate leaves paitially recovered their photosynthetic capacity after 7 d acclimation in warm climate. The hot-climate cultivar showed a broad optimum temperature from 30 to 40 "C, while the cool-climate cultivar showed an upward shift in optimum temperature in the acclimated and warm-climate leaves. In field-grown cassava, maximum of upper canopy leaves was greater than 40 pmol(C02) m'^ s'i when measured in high rainfall season and the rates did not show saturation by radiant energy up to 1800 pmol m'2 s'i PAR. The seasonal average of upper canopy leaves was significantly correlated with both root yield and harvestable biomass. The selection for high in parental materials may lead to high yields when combined with other yield determinants.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2047. Photosynthesis of cockspur [Echinochloa crus-galli (L.) Beauv.] at sites of naturally elevated CO2 concentration
- Creator:
- Vodnik, D., Pfanz, H., Maček, I., Kastelec, D., Lojen, S., and Batič, F.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carbon dioxide springs, chlorophyll, CO2 compensation concentration, intercellular CO2 concentration, net photosynthetic rate, plant height, stomatal conductance, and δ13C
- Language:
- Multiple languages
- Description:
- High abundance of cockspur (Echinochloa crus-galli) at the geothermal carbon dioxide spring area in Stavešinci indicates that this species is able to grow under widely varying CO2 concentrations. Living cockspur plants can even be found very close to gas-releasing vents where growth is significantly reduced. Plant height correlated well with CO2 exposure. The δ13C value of the CO2 spring air was -3.9 ‰ and δ13C values of high-, medium-, and low-CO2 plants were -10.14, -10.44, and -11.95 ‰, respectively. Stomatal response directly followed the prevailing CO2 concentrations, with the highest reduction of stomatal conductance in high CO2 concentration grown plants. Analysis of the curves relating net photosynthetic rate to intercellular CO2 concentration (PN-Ci curves) revealed higher CO2 compensation concentration in plants growing at higher CO2 concentration. This indicates adjustment of respiration and photosynthetic carbon assimilation according to the prevailing CO2 concentrations during germination and growth. There was no difference in other photosynthetic parameters measured. and D. Vodnik ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2048. Photosynthesis of different ecotypes of Miscanthus spp. as affected by water stress
- Creator:
- Weng, J.-H.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- Four dones of Miscanthus spp., collected from regions with different rainfall distribution, were transplanted in pots and subjected to five drying cycles (each of 6- 7 d). Gas exchanges were measured on attached leaves, The light-saturated photosynthetic CO2 uptake (P^) began to dechne when the leaf water potential (y\) was reduced to -1.3 - -1.5 MPa, and the values corresponding to 50 % decrease P^)] were -1.6 - -2.6 MPa. The P^ ) values were lower in a cloně collected from Kilung (northem Taiwan, highly frequent rainfall) than in dones collected from Kenting (southem Taiwan, distinct wet and dry season). Besides, the ^(1/2 Pj^) value became lower in all the tested dones when the drying cycle advanced (in the drying cycle of northem Taiwan cloně and in the 5‘*’ drying cycle of southem Taiwan dones, řespectively). Both the stomatal and non- stomatal factors of photosynthesis were affected by water deficit, and the osmotic adjustment mitigated the negative impact of water deficit on both factors. The clonal differences in the tolerance and acdimation of photosynthesis to water deficit are dosely related to the osmotic adjustment, and the clonal differences in osmotic adjustment reflect the rainfall pattem of sampled region.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2049. Photosynthesis of Hedera canariensis var. azorica variegated leaves as affected by ozone
- Creator:
- Soldatini, G. F., Nali, C., Guidi, L., and Lorenzini, G.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll, fluorescence, ivy, net photosynthetic rate, stomatal conductance, and transpiration
- Language:
- Multiple languages
- Description:
- A differential response to long-term ozone exposures (50 and 100 mm3 m-3) was observed in the green and white areas of variegated leaves of Hedera canariensis var. azorica L. In green tissue the photosynthetic activity was depressed via a stomatal mechanism, and in white regions no effect was observed. Chlorophyll fluorescence parameters remained unchanged in green portions, whereas in the white ones Fm and Fv/Fm significantly diminished following ozone fumigation. and G. F. Soldatini ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2050. Photosynthesis of ozone-sensitive and -resistant Phaseolus vulgaris genotypes under ambient ozone and moderate heat stress
- Creator:
- Villányi, V., Ürmös, Z., Turk, B., Batič, F., and Csintalan, Z.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, AOT40, chlorophyll fluorescence, gas exchange, midday depression, nonphotochemical quenching, ozone sensitivity, snap bean, shaded conditions, Phaseolus vulgaris, heat stress, 2, and 581
- Language:
- Multiple languages
- Description:
- Physiological responses from sensitive (S156) and resistant (R123) genotypes of ozone bioindicator, snap bean, were investigated after exposing the plants to cumulative, phytotoxic ozone amounts. Daily course of gas-exchange parameters showed delayed stomatal response in S156 leaves to environmental changes comparing to the response of R123 leaves. Potential photosynthetic quantum conversion, Stern-Volmer nonphotochemical quenching (NPQ), and maximum photochemical efficiency of PSII (Fv/Fm) values changed differently in the two genotypes between the first and last measuring days. We concluded that the higher ozone sensitivity originated at least partly from inferior regenerating and/or antioxidant capacity. Experimental protocol proved to be determinant on chlorophyll fluorescence parameters: Fv/Fm and NPQ declined at midday, and only the sensitive leaves showed a slight increase in NPQ between 12 h and 16 h. We explained these results by moderately high temperatures and shade-adapted state of our experimental plants under substantial ozone stress. On the base of temperature dependence of minimal fluorescence yield (F0), critical temperature proved to be higher than 32.7°C for Phaseolus vulgaris under these conditions. We found a strong linear correlation between NPQ and nonphotochemical quenching of F0, indicating that NPQ was determined mostly by energy-dependent quenching (qE). The qE is the light-harvesting complex located component of NPQ and depends on the amount of zeaxanthin molecules bound in PSII proteins. Thus, difference between daily courses of NPQ in the two genotypes was probably due to different ways of utilization of the zeaxanthin pool under the interactive effect of ozone and moderate heat stress., V. Villányi, Z. Ürmös, B. Turk, F. Batič, Z. Csintalan., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public