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2873. Screening of certain mangroves for photosynthetic carbon metabolic pathway

Creator:
Venkatesalu, V., Senthilkumar, A., Chandrasekaran, M., and Kannathasan, K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
alanine aminotransferase, asparate aminotransferase, 13C discrimination, C3 carbon metabolic pathway, Kranz syndrome, NADPH-malate dehydrogenase, net photosynthetic rate, phosphoenolpyruvate carboxylase, pyruvate phosphate kinase, and stomata opening
Language:
Multiple languages
Description:
The mangroves Rhizophora lamarkii, Ceriops roxburghiana, Bruguiera gymnorrhiza, Aegiceras corniculatum, and Lumnitzera racemosa were screened for their carbon metabolic pathways by measuring net photosynthetic rate (PN), 13C discrimination rate, leaf anatomy, titratable acidity, and activities of phosphoenolpyruvate carboxylase, NADH-malate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, and pyruvate phosphate dikinase. The tested mangroves had a well developed succulence, opening of stomata during day time and closure in the night hours, and absence of diurnal fluctuation of organic acids in their leaves which excludes the possibility of these species being CAM plants. Moreover, the leaf anatomy had not exhibited Kranz syndrome. The high values of discrimination against 13C, low PN, high CO2 compensation concentration, and the activities of aminotransferases in the direction of alanine formation suggest that the species may follow C3 mode of carbon metabolic pathway. and V. Venkatesalu ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2874. Searching for tolerance to water stress in cotton genotypes: photosynthesi s, stomatal conductance and transpiration

Creator:
Leidi, E. O., López, J. M., López, M., and Gutierrez, J. C.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Net photosynthetic (P^) and transpiration (£) rates and stomatal conductance (gj) were determined in cotton genotypes under drought during the growth cycle. A decrease in P^, E and gs was observed as soil water availability diminished. appeared dosely related to stomatal apertuře at low g^ levels. However, intercellular CO2 concentration was not so much affected by stomatal closure. An important inter- and intra-genotypic variation in g^ was found at the initial sampling dates. Inter-genotypic variation for increased with time, probably as a result of a higher capacity for water uptake in some genotypes.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2875. Seasonal acclimation of stem photosynthesis in two invasive, naturalized legume species from Coastal habitats of California

Creator:
Nilsen, E.T. and Karpa, D.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Responses of stem net photosynthetic rate (P^) to irradiance (/), temperature, vapor pressure, CO2 concentration, nitrogen content, and water potential were studied during early spring (March) and mid summer (latě July) in field populations of two stem photosynthesizing species introduced into Coastal California sites. Stem in Spartium junceum was inhibited in the summer compared with the spring due to low water potential and low tissue nitrogen content. Quantum yield decreased from March to July, along with a decrease in the demand fimction of the C, response curves. Stem conductance was lower at all vapor pressure deficits during the summer, but Cj at a Cg of 350 pmol moE* increased for S. junceum from spring to summer. The thermal optimum for stem did not change between the two seasons, but that of S. junceum was 5 °C higher than that for Cytisus scoparius. The demand function for the Cj curves of C. scoparius also decreased from spring to summer, but the Cj at a Cg of 350 pmol moT* remained unchanged between the seasons. Thus, the water use efficiency of S. junceum decreased in the summer compared with that of the spring while that of C. scoparius remained unchanged between seasons. There was little evidence for compensatory acclimation of stem F^ to changes in climatic conditions in these species.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2876. Seasonal and interannual variations of ecosystem photosynthetic features in an alpine dwarf shrubland on the Qinghai-Tibetan Plateau, China

Creator:
Li, H. Q., Zhang, F. W., Li, Y. N., Cao, G. M., Zhao, L., and Zhao, X. Q.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, fenologie, photosynthesis, phenology, Čína západní, Tibet (Čína), China, Western, ecosystem photosynthetic parameters, eddy covariance technique, leaf area index, rectangular hyperbolic light response, 2, and 581
Language:
Multiple languages
Description:
Ecosystem photosynthetic characteristics are of utmost importance for the estimation of regional carbon budget, but such characteristics are not well understood in alpine regions. We collected CO2 flux data measured by eddy covariance technique over an alpine dwarf shrubland on the Qinghai-Tibetan Plateau during years 2003-2010; and we quantified the temporal patterns of ecosystem apparent quantum yield (a), saturated photosynthetic rate (Pmax), and ecosystem dark respiration (RDe). Results showed that the strong seasonality of a and RDe was driven mainly by air temperature (Ta), whereas that of Pmax was much more determined by leaf area index rather than abiotic factors. Diurnal thermal fluctuation inhibited significantly the daytime photosynthetic capacity. Stepwise regression revealed that the seasonal deviations of a, Pmax, and RDe were significantly controlled by Ta. The annual a was regulated mainly by annual growing season Ta, which indicated that the response of ecosystem a was instant. The annual variations of Pmax correlated positively with soil temperature 5 cm below ground (Ts) of the annual nongrowing season and those of RDe related negatively with the annual nongrowing season precipitation. We suggested that a lagged response regulated the annual Pmax and the annual RDe. Annual deviations of a and RDe were both significantly controlled by annual Ts, and those of Pmax were marginally determined by annual PPFD. Thus, the future warming scenario, especially significant for nongrowing seasonal warming in the Qinghai-Tibetan Plateau, would favor ecosystem photosynthetic capacity in the alpine dwarf shrubland., H. Q. Li, F. W. Zhang, Y. N. LI, G. M. Cao, L. Zhao, X. Q. Zhao., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2877. Seasonal changes in photochemical efficiency in leaves of Halimium halimifolium, a mediterranean semideciduous shrub

Creator:
Zunzunegui, M., Fernandez Baco, L., Diaz Barradas, M. C., and Garcia Novo, F.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, drought, leaf water potential, photosystem 2, plant stress, soil water availability, and stomatal conductance
Language:
Multiple languages
Description:
The relationship between soil water availability, physiological responses [leaf chlorophyll (Chl) fluorescence, leaf water potential (Ψ), and stomatal conductance (gs)] and plant stress was studied in Halimium halimifolium (L.) Willk, Cistaceae, in three sites with contrasted water regimes (Monte Blanco - MB, Monte Intermedio - MI, and Monte Negro - MN) of Doñana National Park (SW of Spain) along the day, in September (summer period) and December (winter period) 1994. In winter, differences among the areas were not significant, with Ψ, gs, and photochemical efficiency values of -1.5 MPa, 0.200 cm s-1, and 0.70, respectively. In summer, however, high declines of gs (0.014 cm s-1 in MI and 0.021 cm s-1 in MB), photochemical efficiency (0.65 Fv/Fp in MB and MI sites) and Ψ (-3.76 in MI and -3.04 MPa in MB) were recorded. Winter-summer differences were minimum in well-watered sites (MN) and maximum in MI. The Ψ and photosystem 2 (PS2) fluorescence were correlated and showed similar seasonal patterns in all three areas. and M. Zunzunegui ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2878. Seasonal changes in photosynthesis and stomatal conductance of five plant species from a semiarid ecosystem

Creator:
Tezara, W., Fernández, M. D., Donoso, C., and Herrera, A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Alternanthera crucis, C3 and C4 plants, Capparis odoratissima, drought, intercellular CO2 concentration, Ipomoeacarnea, Jatropha gossypifolia, photosynthetic rate, and Prosopis juliflora
Language:
Multiple languages
Description:
In order to determine whether stomatal closure alone regulates photosynthesis during drought under natural conditions, seasonal changes in leaf gas exchange were studied in plants of five species differing in life form and carbon fixation pathway growing in a thorn scrub in Venezuela. The species were: Ipomoea carnea, Jatropha gossypifolia, (C3 deciduous shrubs), Alternanthera crucis (C4 deciduous herb), and Prosopis juliflora and Capparis odoratissima (evergreen phreatophytic trees). Xylem water potential (Ψ) of all species followed very roughly the precipitation pattern, being more closely governed by soil water content in I. carnea and A. crucis. Maximum rate of photosynthesis, Pmax, decreased with Ψ in I. carnea, J. gossypifolia, and A. crucis. In I. carnea and J. gossypifolia stomatal closure was responsible for a 90 % decline in net photosynthetic rate (PN) as Ψ decreased from -0.3 to -2.0 MPa, since stomatal conductance (gs) was sensitive to water stress, and stomatal limitation on PN increased with drought. In A. crucis, PN decreased by 90 % at a much lower Ψ (-9.3 MPa), and gs was relatively less sensitive to Ψ. In P. juliflora and C. odoratissima, Pmax, gs, and intercellular CO2 concentration (Ci) were independent of soil water content. In the C3 shrubs stomatal closure was apparently the main constraint on photosynthesis during drought, Ci declining with Ψ in I. carnea. In the C4 herb, Ci was constant along the range of Ψ values, which suggested a coordinated decrease in both gs and mesophyll capacity. In P. juliflora Ci showed a slow decrease with Ψ which may have been due to seasonal leaf developmental changes, rather than to soil water availability. and W. Tezara ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2879. Seasonal changes in the photosynthetic capacity of cones on a larch (Larix kaempferi) canopy

Creator:
Wang, W.-J., Watanabe, Y., Endo, I., Kitaoka, S., and Koike, T.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll, re-fix ratio, respiration, seasonal changes, and stomata
Language:
Multiple languages
Description:
The seasonal changes of photosynthesis of cones of Japanese larch (Larix kaempferi Carr.) trees showed that gross photosynthetic rate of young cones (G) was 2-3 µmol m-2 s-1 at surface area unit and PG / RD (dark respiration of cones) peaked about 0.7 in the same period, indicating that 70 % of respiratory CO2 was re-fixed. With maturation, PG and PG / RD sharply decreased. Chlorophyll content in cones was 3-20 % of that in leaves, which made it a limiting factor for photosynthesis and its content was closely correlated with photosynthetic capacity. Although sunken and linearly arranged stomatal organs were found on the scale of young cones, differently from the significant regulation of leaf photosynthesis, these stomata tended to be non-functional since CO2 is not limiting factor for cone photosynthesis. Thus photosynthesis of larch cones is an additional contribution to their development. and W.-J. Wang ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2880. Seasonal changes of selected parameters of CO2 fixation biochemistry of Norway spruce under the long-term impact of elevated CO2

Creator:
Urban, O. and Marek, M. V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
acclimation depression, carbon sink, CO2 assimilation, elevated CO2 concentration, electron transport, Picea abies, and ribulose-1,5-bisphosphate carboxylase/oxygenase
Language:
Multiple languages
Description:
Twelve-year-old Norway spruce (Picea abies [L.] Karst.) trees were exposed to ambient (AC) or elevated (EC) [ambient + 350 µmol(CO2) mol-1] CO2 concentrations in open-top-chamber (OTC) experiment under the field conditions of a mountain stand. Short-term (4 weeks, beginning of the vegetation season) and long-term (4 growing seasons, end of the vegetation season) effects of this treatment on biochemical parameters of CO2 assimilation were evaluated. A combination of gas exchange, fluorescence of chlorophyll a, and application of a mathematical model of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activity was used. The analysis showed that the depression of photosynthetic activity by long-term impact of elevated CO2 was mainly caused by decreased RuBPCO carboxylation rate. The electron transport rate as well as the rate of ribulose-1,5-bisphosphate (RuBP) formation were also modified. These modifications to photosynthetic assimilation depended on time during the growing season. Changes in the spring were caused mainly by local deficiency of nitrogen in the assimilating tissue. However, the strong depression of assimilation observed in the autumn months was the result of insufficient carbon sink capacity. and O. Urban, M. V. Marek.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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