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175. Modelling photosynthesis in shallow algal production ponds

Creator:
Ritchie, R. J. and Larkum, A. W. D.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, algal production ponds, Chlorella, Dunaliella, electron transport rate, light saturation curves, Phaeodactylum, photoinhibition, photosynthesis, photosynthesis vs. depth, primary productivity, pulse amplitude modulation fluorometry, 2, and 58
Language:
Multiple languages
Description:
a1_Shallow ponds with rapidly photosynthesising cyanobacteria or eukaryotic algae are used for growing biotechnology feedstock and have been proposed for biofuel production but a credible model to predict the productivity of a column of phytoplankton in such ponds is lacking. Oxygen electrodes and Pulse Amplitude Modulation (PAM) fluorometer technology were used to measure gross photosynthesis (PG) vs. irradiance (E) curves (PG vs. E curves) in Chlorella (chlorophyta), Dunaliella salina (chlorophyta) and Phaeodactylum (bacillariophyta). PG vs. E curves were fitted to the waiting-in-line function [PG = (PGmax × E/Eopt) × exp(1 — E/Eopt)]. Attenuation of incident light with depth could then be used to model PG vs. E curves to describe PG vs. depth in pond cultures of uniformly distributed planktonic algae. Respiratory data (by O2-electrode) allowed net photosynthesis (PN) of algal ponds to be modelled with depth. Photoinhibition of photosynthesis at the pond surface reduced PN of the water column. Calculated optimum depths for the algal ponds were: Phaeodactylum, 63 mm; Dunaliella, 71 mm and Chlorella, 87 mm. Irradiance at this depth is ≈ 5 to 10 μmol m-2 s-1 photosynthetic photon flux density (PPFD). This knowledge can then be used to optimise the pond depth. The total net P N [μmol(O2) m-2 s-1] were: Chlorella, ≈ 12.6 ± 0.76; Dunaliella, ≈ 6.5 ± 0.41; Phaeodactylum ≈ 6.1 ± 0.35. Snell’s and Fresnel’s laws were used to correct irradiance for reflection and refraction and thus estimate the time course of PN over the course of a day taking into account respiration during the day and at night. The optimum PN of a pond adjusted to be of optimal depth (0.1-0.5 m) should be approximately constant because increasing the cell density will proportionally reduce the optimum depth of the pond and vice versa., a2_Net photosynthesis for an optimised pond located at the tropic of Cancer would be [in t(C) ha-1 y-1]: Chlorella, ≈ 14.1 ± 0.66; Dunaliella, ≈ 5.48 ± 0.39; Phaeodactylum, ≈ 6.58 ± 0.42 but such calculations do not take weather, such as cloud cover, and temperature, into account., R. J. Ritchie, A. W. D. Larkum., and Obsahuje bibliografii a dodatky
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

176. Modulated increased UV-B radiation affects crop growth and grain yield and quality of maize in the field

Creator:
Yin, L. N. and Wang, S. W.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, growth, maize, quality, UV-B radiation, yield, 2, and 58
Language:
Multiple languages
Description:
Current research on the effect of increased UV-B radiation on crop production has been limited to exposing plants to improbable UV-B dose or growth condition. The objective of this study was to test the effects of short-term modulated increased UV-B radiation on maize (Zea mays L.) growth, grain yield, and quality under field conditions for three years. A modulated irradiance system was used to maintain UV-B radiation at 30% above the ambient level and was applied daily between the elongation and silking stages of maize. The result indicated that increased UV-B radiation adversely affected maize growth and yield, especially on plant height when UV-B was enhanced at the elongation stage and on yield when UV-B was enhanced near the silking stage. Yield reduction that induced by enhanced UV-B radiation was associated with reductions in number of kernels per row and kernel mass. Protein content of grains was increased with enhanced UV-B radiation, but oil and starch contents were not affected. This study confirmed the sensitivity of maize to increased UV-B radiation under the field condition, and contributed to understand the full negative and positive effects of increased UV-B radiation on crop production., L. N. Yin, S. W. Wang., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

177. Mokřadní louky Sedlčanska - střípky z krajin minulých

Creator:
Jiří Malíček
Format:
print
Type:
article, články, model:article, and TEXT
Subject:
Botanika, flóra, mokřadní ekosystémy, louky, mokřady, Sedlčany (Česko), 2, and 58
Language:
Czech
Description:
In contrast to the typical Central Bohemian landscape, the Sedlčany region is characterized by quite a high concentration of wet meadows; most of them discovered during the last few years. Though it is only a fragment of their original extent. Suitable management is absent at most localities, but a restoration of farming on selected meadows has recently been started. and J.Malíček.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

178. Monitoring moderate Cu and Cd toxicity by chlorophyll fluorescence and P700 absorbance in pea leaves

Creator:
Wodala, B., Eitel, G., Gyula, T. N., Ördög, A., and Horváth, F.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, Cd2+, chlorophyll fluorescence, Cu2+, heavy metal stress, P700 absorbance, photosynthetic electron transport, PSI photochemistry, PSII photochemistry, 2, and 58
Language:
Multiple languages
Description:
We investigated the effect of moderate Cu2+ and Cd2+ stress by applying chlorophyll (Chl) fluorescence and P700 absorbance measurements to monitor the photosynthetic electron transport activity of 3-week-old Pisum sativum L. cv. Petit Provençal plants grown in a modified Hoagland solution containing 50 μM CuSO4 or 5 μM CdCl2. Both heavy metals caused a slight inhibition in PSII photochemistry as indicated by the decrease in the effective quantum efficiency of PSII (ΦPSII), the maximum electron transport capacity (ETRmax), and the maximum quantum yield for electron transport (α). PSI photochemistry was also affected by these heavy metals. Cu2+ and Cd2+ decreased the quantum efficiency of PSI (ΦPSI) as well as the number of electrons in the intersystem chain, and the Cu2+ treatment significantly reduced the number of electrons from stromal donors available for PSI. These results indicate that PSII and PSI photochemistry of pea plants are both sensitive to moderate Cu2+ and Cd2+ stress, which in turn is easily detected and monitored by Chl fluorescence and P700 absorbance measurements. Therefore, monitoring the photochemistry of pea plants with these noninvasive, yet sensitive techniques offers a promising strategy to study heavy metal toxicity in the environment., B. Wodala ... [et al.]., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

179. Multi-objective environment chamber system for studying plant responses to climate change

Creator:
Zhou, X., Ge, Z. M., Kellomäki, S., Wang, K. Y., Peltola, H., Martikainen, P. J., Lemettinen, M., Hassinen, A., and Ikonen, R.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, autocontrolled environment chamber, boreal grass, chamber effect, climate change, 2, and 58
Language:
Multiple languages
Description:
This paper describes the technical information and performance of a new multi-objective chamber system enabling the control of environmental variables (e.g., temperature, CO2, air humidity, wind speed, and UV-B radiation) for understanding plant responses to climate change. Over a whole growing season, four different climate scenarios were evenly programmed into the system’s 16 chambers as ambient environment (AMB), elevated temperature (ET), elevated CO2 concentration (EC) and elevated temperature and CO2 concentration (ETC). Simultaneously, the chamber effects were assessed regarding the physiological responses and growth of a boreal perennial grass (reed canary grass, Phalaris arundinacea L.). During the growing season, the chamber system provided a wide variety of climatic conditions for air temperature (T a), relative humidity (RH) and CO2 concentration (C a) in the AMB chambers following outside conditions. The target temperature (+3.5°C) was achieved to a good degree in the ET and ETC chambers, being on average 3.3°C and 3.7°C higher than ambient conditions, respectively. The target concentration of CO2 (700 ppm) was also well achieved in the EC and ETC chambers, being on average 704 ppm and 703 ppm, respectively. The stable airflow condition inside all of the chambers provided a homogeneous distribution of gases and temperature. The decreases in RH and increases in vapour pressure deficit (VPD) in the elevated temperature chambers were also maintained at a low level. Chamber effects were observed, with some physiological and growth parameters of plants being significantly lower in the AMB chambers, compared to outside conditions. The plant growth was negatively affected by the reduced radiation inside the chambers., X. Zhou ... [et al.]., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

180. Na jih za severskými rašeliništi

Creator:
Michal Hájek and Petra Hájková
Format:
print
Type:
article, články, model:article, and TEXT
Subject:
Botanika, flóra, mokřadní ekosystémy, rašeliniště, mokřady, Bulharsko, 2, and 58
Language:
Czech
Description:
Recent research in isolated Bulgarian mires has discovered many unknown disjunct populations of boreal vascular plant and bryophyte species. These findings draw attention to these recently endangered mires which represent a source of very important scientific information. and Michal Hájek, Petra Hájková.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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