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1922. Parameter inversion estimation in photosynthetic models: impact of different simulation methods

Creator:
Wang, H. B., Ma, M. G., Xie, Y. M., Wang, X. F., and Wang, J.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, modelování a simulace, photosynthesis, modeling and simulation, optimization algorithms, PN/Ci curve, parameter estimation, photosynthetic models, 2, and 581
Language:
Multiple languages
Description:
When we apply ecological models in environmental management, we must assess the accuracy of parameter estimation and its impact on model predictions. Parameters estimated by conventional techniques tend to be nonrobust and require excessive computational resources. However, optimization algorithms are highly robust and generally exhibit convergence of parameter estimation by inversion with nonlinear models. They can simultaneously generate a large number of parameter estimates using an entire data set. In this study, we tested four inversion algorithms (simulated annealing, shuffled complex evolution, particle swarm optimization, and the genetic algorithm) to optimize parameters in photosynthetic models depending on different temperatures. We investigated if parameter boundary values and control variables influenced the accuracy and efficiency of the various algorithms and models. We obtained optimal solutions with all of the inversion algorithms tested if the parameter bounds and control variables were constrained properly. However, the efficiency of processing time use varied with the control variables obtained. In addition, we investigated if temperature dependence formalization impacted optimally the parameter estimation process. We found that the model with a peaked temperature response provided the best fit to the data., H. B. Wang, M. G. Ma, Y. M. Xie, X. F. Wang, J. Wang., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1924. Partial compensation in Psychotria marginata (Rubiaceae) after simulated defoliation increases photon capture and photosynthesis

Creator:
Gálvez, D. and Cohen-Fernández, A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
computer modelling, daily carbon gain, and photo capture
Language:
Multiple languages
Description:
We used Y-plant, a computer-based model of plant crown architecture analysis, to simulate effects of defoliation on daily canopy carbon gain in Psychotria marginata (Rubiaceae) plants under two contrasting irradiances. Five levels of defoliation were simulated using two different types of leaf blade damage. Compensatory increases in photon-saturated photosynthetic capacity (Pmax) of 25, 50, and 100 % defoliation were also simulated. In all simulations daily photon capture and CO2 assimilation increased with defoliation. However, without a compensatory response, daily canopy carbon gain also decreased with defoliation. Under high irradiance, reduction in daily canopy carbon gain was less than what would be expected if the response was proportional to leaf area reduction. Thus, 25 and 50 % defoliation resulted in only 20 and 41 % of daily canopy carbon gain reduction, respectively. In the scenario where 25 % of the leaf area was removed, if the Pmax value was increased by 25 %, the remaining leaves compensated for 94 % of the daily canopy carbon relative to an undamaged non-compensated plant. At the same defoliation level, incrementing Pmax values by 50 and 100 % resulted in overcompensation. Hence, because the increment of daily photon capture and CO2 assimilation after defoliation was more a passive consequence of the reduction in leaf area than an active response, under the conditions tested photosynthetic compensation could be only possible through an active mechanism such as the increment of Pmax values. and D. Gálvez, A. Cohen-Fernández.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1925. Partial shade improved the photosynthetic capacity and polysaccharide accumulation of the medicinal plant Bletilla ochracea Schltr.

Creator:
Yu, X. F., Ming, X. Y., Xiong, M., Zhang, C., Yue, L. J., Yang, L., and Fan, C. Y.
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
Bletilla ochracea Schltr., chlorophyll fluorescence, photosynthesis, and shade
Language:
Multiple languages
Description:
To study the light intensity suitable for Bletilla ochracea Schltr., morphology, photosynthetic parameters, and polysaccharide content of seedlings were evaluated under different light intensities. All shade treatments promoted plant growth and net photosynthetic rate while having no significant effect on transpiration rate. The maximum photochemical efficiency and potential photochemical efficiency reached the lowest values under full sunlight. The electron transport rate and photochemical quenching under shade were significantly higher than those under full light, while nonphotochemical quenching was the highest under full light. This indicated that the shade alleviated photoinhibition in summer and improved the utilization of light. B. ochracea could adapt to different light intensities, enhancing photosynthetic efficiency under low light by improving the electron transport and the degree of opened PSⅡ reaction centers, and adapting to high light by increasing heat dissipation. Plant growth, photosynthesis, and polysaccharide accumulation of B. ochracea greatly increased under 76.4% shade.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1926. Participation of stems and leaves in photosynthetic assimilation of CO2 in lilac (Syringa vulgaris L.)

Creator:
Pilarski, J.
Format:
print
Type:
model:internalpart and TEXT
Subject:
bark, chloroplast, chlorophyll, infrared gas analysis, oxygen electrode, and photorespiration
Language:
Multiple languages
Description:
Photosynthetic assimilatíon of CO2 in a four-year-old plant of lilac, measured in April and in July, was compared. The results were calculated with regard to the surface area of the particular year groups of the stems and to the total surface area of the stems as well as to the globál surface area of the leaves of the plant. In April the stems were the only site of photosynthesis. In July the main organs of CO2 assimilatíon were the leaves, while the participation of the shoots in that period amounted to 2 %. In the process of photosynthesis in the stems mainly the endogenous CO2 was utilized, while the share of exogenous CO2 was 0.02 %. The potential photosynthesis was determined also on the basis of measurements of oxygen release by chloroplasts isolated from the bark and leaves. In July the production of oxygen by chloroplasts ffom the bark of all stems was 5 % of the amount of oxygen released by the chloroplasts isolated from the leaves. In April the production of oxygen by chloroplasts isolated from the bark of the particular year groups of the stems was higher than in July. In the process of CO2 assimilatíon by the bark and leaves the potential Chemical activity of chloroplasts was not fully utilized. The potential CO2 assimilatíon by chloroplasts isolated from the bark was 8.5 times greater than the measured results of CO2 exchange in July and 35.8 times greater in April.
Rights:
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1927. Partitioning of 14C-photosynthate of leaves in roots, rhizome, and in essential oil and curcumin in turmeric (Curcuma longa L.)

Creator:
Dixit, Deeksha and Srivastava, N. K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
amino acids, 14CO2 incorporation, leaf age, organic acids, primary and secondary metabolites, rhizome, root, stem, and sugars
Language:
Multiple languages
Description:
Incorporation of photosynthetically fixed 14C was studied at different time intervals of 12, 24, and 36 h in various plant parts-leaf 1 to 4 from apex, roots, and rhizome-into primary metabolites-sugars, amino acids, and organic acids, and secondary metabolites-essential oil and curcumin-in turmeric. The youngest leaves were most active in fixing 14C at 24 h. Fixation capacity into primary metabolites decreased with leaf position and time. The primary metabolite levels in leaves were maximal in sugars and organic acids and lowest in amino acids. Roots as well as rhizome received maximum photoassimilate from leaves at 24 h; this declined with time. The maximum metabolite concentrations in the roots and rhizome were high in sugars and organic acids and least in amino acids. 14C incorporation into oil in leaf and into curcumin in rhizome was maximal at 24 h and declined with time. These studies highlight importance of time-dependent translocation of 14C-primary metabolites from leaves to roots and rhizome and their subsequent biosynthesis into secondary metabolite, curcumin, in rhizome. This might be one of factors regulating the secondary metabolite accumulation and rhizome development. and Deeksha Dixit, N. K. Srivastava.
Rights:
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1928. Partitioning of photosynthetic electron flow between CO2 assimilation and O2 reduction in sunflower plants under water deficit

Creator:
Tezara, W., Driscoll, S., and Lawlor, D. W.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, electron transport, fluorescence quenching, Helianthus annuus, intercellular CO2 concentration, net photosynthetic rate, and stomatal conductance
Language:
Multiple languages
Description:
In sunflower (Helianthus annuus L.) grown under controlled conditions and subjected to drought by withholding watering, net photosynthetic rate (PN) and stomatal conductance (gs) of attached leaves decreased as leaf water potential (Ψw) declined from -0.3 to -2.9 MPa. Although gs decreased over the whole range of Ψw, nearly constant values in the intercellular CO2 concentrations (Ci) were observed as Ψw decreased to -1.8 MPa, but Ci increased as Ψw decreased further. Relative quantum yield, photochemical quenching, and the apparent quantum yield of photosynthesis decreased with water deficit, whereas non-photochemical quenching (qNP) increased progressively. A highly significant negative relationship between qNP and ATP content was observed. Water deficit did not alter the pyridine nucleotide concentration but decreased ATP content suggesting metabolic impairment. At a photon flux density of 550 µmol m-2 s-1, the allocation of electrons from photosystem (PS) 2 to O2 reduction was increased by 51 %, while the allocation to CO2 assimilation was diminished by 32 %, as Ψw declined from -0.3 to -2.9 MPa. A significant linear relationship between mean PN and the rate of total linear electron transport was observed in well watered plants, the correlation becoming curvilinear when water deficit increased. The maximum quantum yield of PS2 was not affected by water deficit, whereas qP declined only at very severe stress and the excess photon energy was dissipated by increasing qNP indicating that a greater proportion of the energy was thermally dissipated. This accounted for the apparent down-regulation of PS2 and supported the protective role of qNP against photoinhibition in sunflower. and W. Tezara, S. Driscoll, D. W. Lawlor.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1929. Partitioning of photosynthetically fixed 14CO2 Into oil and curcumin accumulation in Curcuma longa grown under iron deficiency

Creator:
Dixit, Deeksha and Srivastava, N. K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
animo acids, Fe, leaf position, organic acids, primary and secondary metabolites, sugars, and turmeric
Language:
Multiple languages
Description:
Changes in leaf growth, photosynthetic efficiency, and incorporation pattern of photosynthetically fixed 14CO2 in leaves 1 and 2 from plant apex, in roots, and rhizome induced in Curcuma by growing in a solution culture at Fe concentration of 0 and 5.6 g m-3 were studied. 14C was incorporated into primary metabolites (sugars, amino acids, and organic acids) and secondary metabolites (essential oil and curcumin). Fe deficiency resulted in a decrease in leaf area, its fresh and dry mass, chlorophyll (Chl) content, and CO2 exchange rate at all leaf positions. The rate of 14CO2 fixation declined with leaf position, maximum being in the youngest leaf. Fe deficiency resulted in higher accumulation of sugars, amino acids, and organic acids in leaves at both positions. This is due to poor translocation of metabolites. Roots and rhizomes of Fe-deficient plants had lower concentrations of total photosynthate, sugars, and amino acids whereas organic acid concentration was higher in rhizomes. 14CO2 incorporation in essential oil was lower in the youngest leaf, as well as incorporation in curcumin content in rhizome. Fe deficiency influenced leaf area, its fresh and dry masses, CO2 exchange rate, and oil and curcumin accumulation by affecting translocation of assimilated photosynthates. and Deeksha Dixit, N. K. Srivastava.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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