Previous studies indicate that the degree of UV-Binduced photosynthetic inhibition may be highly dependent upon the photosynthetic photon flux density (PPFD, total quantum flux in the waveband 400-700 nm) incident on a plant. This study illustrates that Essex soybean leaves (Glycine max) preconditioned under high PPFD suffered less UV-B-induced photoinhibition than when preconditioned under low PPFD. However, sensitivity to UV-B increased when soybean leaves received high-PPFD as a concomitant treatment. The relative msgnitude of UV-B-induced damage was similar for both light-limited and light-saturated photosynthesis. This probably indicates that UV-B is inhibiting fundamentally different photosynthetic processes. Soybean leaves preconditioned under high PPFD had greater specific-leaf-weight, chlorophyll a/b ratio, and crude flavonoid content. The total chlorophyll concentration of soybean leaves preconditioned under high PPFD increased slightly over a UV-B irradiation period of five hours. Total chlorophyll concentration of leaves preconditioned under low PPFD decreased slightly in response to the same irradiation period.

Marine microbes are an essential component of global biogeochemical cycles. In oligotrophic marine surface waters, the phytoplankton, phototrophic, single-celled (on occasion, colonial) organisms, is often dominated by the picoplankton (cells <2 micrometers in size), which constitute the base of the marine food chain. The picophytoplankton is composed of three main groups of organisms: two genera of cyanobacteria, Prochlorococcus and Synechococcus, and a third group, the picoeukaryotes. Even though numerically less abundant than cyanobacteria, picoeukaryotes can contribute significantly to biomass and primary production in this size fraction. Furthermore, picoeukaryotes are a diverse group but this diversity is still underexplored and their ecological roles and physiology is poorly understood. Here uncultured protists are investigated using 18S rRNA gene clone libraries, phylogenetic analyses, specific fluorescence in situ hybridization (FISH) probes and other methods in tropical and subtropical waters. Gene sequences comprising a unique eukaryotic lineage, biliphytes, were identified in most samples, whether from high (30 degrees Celsius) or low (5 degrees Celsius) temperature waters. Sequences within this uncultured group have previously been retrieved from mid and high latitudes. Phycobilin-like fluorescence associated with biliphyte-specific FISH probed cells indicated they may be photosynthetic. Furthermore, the data indicated biliphytes are nanoplanktonic in size, averaging between 3.0 and 4.1 micrometers. Using the 18S rRNA gene, sequences belonging to a broadly distributed but uncultivated pico-prymnesiophytes were retrieved. We investigated the ecological importance of these natural pico-prymnesiophyte populations and field experiments showed that they could grow rapidly and contributed measurably to primary production. They also appear to form a large portion of global picophytoplankton biomass, with differing contributions in five biogeographical provinces, from tropical to high latitudes. Finally, the physiology of the picoeukaryote Micromonas was studied under a shift from medium to high light and UV radiation. Results showed that the growth of these photosynthetic cells was synchronized with the light: dark period. Forward angle side scatter and red autofluorescence from chlorophyll increased throughout the light period and decreased during the dark period. This is consistent with cell division occurring at the beginning of the dark period. Additionally, genes proposed to have roles in photoprotection were up-regulated under high light and UV, but not in controls.

<p>Elevated temperatures accompanying climate warming are expected to have adverse effects on sensitive lichen species. This premise was examined by measuring the sensitivity of different lichen species to elevated temperatures in the laboratory and in the field. Laboratory studies involved the exposure of nine hydrated lichen species (Xanthoparmelia austro-africana, X. hyporhytida, Xanthoparmelia sp., Xanthomaculina hottentotta, Teloschistes capensis, Ramalina sp., Flavopuntelia caperata, Lasallia papulosa, Parmotrema austrosinensis) collected from sites of different aridity and mean annual temperature for 2 hourly intervals to temperatures ranging from 24&ordm / C to 48&ordm / C in a forced daft oven and measuring their respiration rates and maximum quantum yield of PSII. Field studies involved simultaneous hourly measurements of ground surface air temperatures and Lichen effective quantum yield of PSII of hydrated lichen species populations under ambient and artificially modified environmental conditions.</p>

With greenhouse gas emissions (of which CO2 is the major component) being a major environmental concern, mitigation of those emissions is becoming increasingly imperative. The ability to use a fast growing, photosynthetic organism like microalgae that can survive primarily on nutrients such as sunlight and air (with increased CO2 levels) makes it a desirable agent for CO2 sequestration. The primary goal of this project is the engineering of the sequestration of CO2 using the cultivation of the microalgae species <i>Chlorella vulgaris</i>. Secondary goals of the project are the exploration and development of valuable by-products of the cultivation and the determination of whether utilizing microalgae to capture CO2 could be integrated economically into an industrial facility.<p> The batch growth kinetics of the photosynthetic algal species <i>C. vulgaris</i> were investigated using a well-mixed stirred bioreactor. The growth rate was found to increase as the dissolved CO2 increased to 150 mg/L (10% CO2 by volume in the gas), but fell dramatically at higher concentrations. Increasing the radiant flux also increased growth rate. With a radiant flux of 32.3 mW falling directly on the 500 mL culture media, the growth rate reached up to 3.6 mg of cells/L-h. Both pH variation (5.5 - 7.0) and mass transfer rate of CO2 (KLa between 6 h-1 and 17 h-1) had little effect on growth rate.<p> The operation of continuously stirred tank bioreactors (CSTBs) at minimum cost is a major concern for operators. In this work, a CSTB design strategy is presented where impeller stirring speed and aeration rate are optimized to meet the oxygen demand of growing cells, simultaneously minimizing the capital and operating cost. The effect of microbial species, ions in the culture medium, impeller style, as well as changing CSTB size and biomass input density on the optimum operating conditions, is examined. A study of the effects of various parameters on the CSTB design is shown.<p> Using the kinetic data collected in the batch growth study, a novel external loop airlift photobioreactor (ELAPB) was designed and tested. A model was developed for <i>C. vulgaris</i> growth in the ELAPB that incorporated growth behaviour, light attenuation, mass transfer, and fluid dynamics. The model predicts biomass accumulation, light penetration, and transient CO2 concentrations, and compares predictions to experimental data for radiant fluxes of 0.075 1.15 W/m2 and 0 20% CO2 enrichment of feed air, with a 10% average error. The effect of radiant flux and CO2 concentration is presented with discussion of radial and vertical profiles along the column. For a fed-batch culture at a biomass density of 170 mg/L, the penetration of the radiant flux was found to decrease by 50% within the first 1 cm, and 75% at 2 cm. Theoretical optimum growth conditions are determined to be 0.30 W/m2 and 6% CO2 enrichment of inlet feed air.<p> The algal culture was observed to be a workable electron acceptor in a cathodic half cell. A net potential difference of 70 mV was achieved between the growing <i>C. vulgaris</i> culture acting as a cathode and a 0.02 M potassium ferrocyanide anodic half cell. Surge current and power levels of 1.0 µA/mg of cell dry weight and 2.7 mW/m2 of cathode surface area were measured between these two half cells. The recently developed photosynthetic cathode was also coupled to a fermentative anode to produce a completely microbial fuel cell. Loading effects and the effect of changing culture conditions on fuel cell operation are reported. The maximum power output measured was 0.95 mW/ m2 at 90 V and 5000 ohms. A significant increase in this output is achieved with the addition of supplemental glucose to the anodic half cell and the enrichment of the feed air bubbled into the cathodic half cell with 10% CO2.<p> Two economic feasibility studies were performed on the integration of ELAPBs into an industrial facility. These integration studies operated the ELAPBs continuously as biocathodes in coupled microbial fuel cells (MFCs) that capture CO2 from an existing 130 million L/yr bioethanol plant, while generating electrical power and yielding oil for biodiesel to provide operational revenue to offset costs. The anodes for the coupled MFCs are the existing yeast batch fermentors, and the CO2 to be sequestered comes from the existing bioethanol production. Two different design schemes were evaluated, in both cases the maximum profit was achieved with the maximum number of tall columns operated in parallel. The first design evaluated a batch bioethanol facility with off-site oil processing, and the economic feasibility is demonstrated by the positive Net Present Worth achieved over the 20 year life of the plant, at a 10% rate of return on investment. The second design, for a continuous bioethanol operation, processes both oil and algae biomass on-site, but the economics of this second process are only positive (Internal Rate of Return 9.93%.) if the government provides financial assistance in the form of generous carbon credits (a speculative $100 per tonne of CO2 not yet attained) and a 25% capital equipment grant.

Eddy-covariance (EC) CO₂ flux data were analysed and annual carbon (C) balances estimated for a four-year period (2004-2007) following clearcut harvesting of a boreal jack pine stand in northern Saskatchewan. The site was a source of C to the atmosphere for all years, with annual net ecosystem productivity (NEP) increasing from -153 g C m⁻² yr⁻¹ in 2004 to -63 g C m⁻² yr⁻¹ in 2007. This increase was mainly due to gross primary productivity (GPP) increasing significantly from 78 to 200 g C m⁻² yr⁻¹ , while ecosystem respiration (R) increased only slightly from 231 to 263 g C m⁻² yr⁻¹ over the same period. In the 2006 growing season (GS), a field campaign was conducted to investigate the relationships between monthly destructive measurements of leaf area index (LAI) and daily measurements of the normalized difference vegetation index (NDVI) and photosynthetic capacity (Amax). The latter was derived from 5-day, 16-day, 30-day and annual Michaelis-Menten light response analyses using daytime measurements of NEP and incident photosynthetically active radiation. Digital-camera data were used to evaluate the potential of using the rectilinear-lens vegetation index (RLVI) as a surrogate for NDVI of a young forest stand. Results showed that LAI was linearly related to NDVI and RLVI, which was largely the result of changes in the deciduous vegetation component across the GS. These results indicate that RLVI could be used as a surrogate for NDVI up to a GS maximum LAI of 0.91 m2 m⁻² observed in 2006. Measured mean (± 1 S.D.) GS LAI was 0.67 (± 0.24) m² m⁻² in 2006. LAI accounted for the majority of the variability in Amax at the 30-day time scale, while at shorter time scales air temperature was the dominant control. For 2004 to 2007, mean spring estimates of LAI were 0.25, 0.29, 0.38 (compared to 0.40 m² m⁻² from measurements) and 0.41 m² m⁻², respectively. Results suggest that a steady increase in the jack pine LAI component accounted for the annual increases in GPP and hence NEP over the four years.

With greenhouse gas emissions (of which CO2 is the major component) being a major environmental concern, mitigation of those emissions is becoming increasingly imperative. The ability to use a fast growing, photosynthetic organism like microalgae that can survive primarily on nutrients such as sunlight and air (with increased CO2 levels) makes it a desirable agent for CO2 sequestration. The primary goal of this project is the engineering of the sequestration of CO2 using the cultivation of the microalgae species <i>Chlorella vulgaris</i>. Secondary goals of the project are the exploration and development of valuable by-products of the cultivation and the determination of whether utilizing microalgae to capture CO2 could be integrated economically into an industrial facility.<p> The batch growth kinetics of the photosynthetic algal species <i>C. vulgaris</i> were investigated using a well-mixed stirred bioreactor. The growth rate was found to increase as the dissolved CO2 increased to 150 mg/L (10% CO2 by volume in the gas), but fell dramatically at higher concentrations. Increasing the radiant flux also increased growth rate. With a radiant flux of 32.3 mW falling directly on the 500 mL culture media, the growth rate reached up to 3.6 mg of cells/L-h. Both pH variation (5.5 - 7.0) and mass transfer rate of CO2 (KLa between 6 h-1 and 17 h-1) had little effect on growth rate.<p> The operation of continuously stirred tank bioreactors (CSTBs) at minimum cost is a major concern for operators. In this work, a CSTB design strategy is presented where impeller stirring speed and aeration rate are optimized to meet the oxygen demand of growing cells, simultaneously minimizing the capital and operating cost. The effect of microbial species, ions in the culture medium, impeller style, as well as changing CSTB size and biomass input density on the optimum operating conditions, is examined. A study of the effects of various parameters on the CSTB design is shown.<p> Using the kinetic data collected in the batch growth study, a novel external loop airlift photobioreactor (ELAPB) was designed and tested. A model was developed for <i>C. vulgaris</i> growth in the ELAPB that incorporated growth behaviour, light attenuation, mass transfer, and fluid dynamics. The model predicts biomass accumulation, light penetration, and transient CO2 concentrations, and compares predictions to experimental data for radiant fluxes of 0.075 1.15 W/m2 and 0 20% CO2 enrichment of feed air, with a 10% average error. The effect of radiant flux and CO2 concentration is presented with discussion of radial and vertical profiles along the column. For a fed-batch culture at a biomass density of 170 mg/L, the penetration of the radiant flux was found to decrease by 50% within the first 1 cm, and 75% at 2 cm. Theoretical optimum growth conditions are determined to be 0.30 W/m2 and 6% CO2 enrichment of inlet feed air.<p> The algal culture was observed to be a workable electron acceptor in a cathodic half cell. A net potential difference of 70 mV was achieved between the growing <i>C. vulgaris</i> culture acting as a cathode and a 0.02 M potassium ferrocyanide anodic half cell. Surge current and power levels of 1.0 µA/mg of cell dry weight and 2.7 mW/m2 of cathode surface area were measured between these two half cells. The recently developed photosynthetic cathode was also coupled to a fermentative anode to produce a completely microbial fuel cell. Loading effects and the effect of changing culture conditions on fuel cell operation are reported. The maximum power output measured was 0.95 mW/ m2 at 90 V and 5000 ohms. A significant increase in this output is achieved with the addition of supplemental glucose to the anodic half cell and the enrichment of the feed air bubbled into the cathodic half cell with 10% CO2.<p> Two economic feasibility studies were performed on the integration of ELAPBs into an industrial facility. These integration studies operated the ELAPBs continuously as biocathodes in coupled microbial fuel cells (MFCs) that capture CO2 from an existing 130 million L/yr bioethanol plant, while generating electrical power and yielding oil for biodiesel to provide operational revenue to offset costs. The anodes for the coupled MFCs are the existing yeast batch fermentors, and the CO2 to be sequestered comes from the existing bioethanol production. Two different design schemes were evaluated, in both cases the maximum profit was achieved with the maximum number of tall columns operated in parallel. The first design evaluated a batch bioethanol facility with off-site oil processing, and the economic feasibility is demonstrated by the positive Net Present Worth achieved over the 20 year life of the plant, at a 10% rate of return on investment. The second design, for a continuous bioethanol operation, processes both oil and algae biomass on-site, but the economics of this second process are only positive (Internal Rate of Return 9.93%.) if the government provides financial assistance in the form of generous carbon credits (a speculative $100 per tonne of CO2 not yet attained) and a 25% capital equipment grant.

Chlamydomonas reinhardtii can utilize CO2 for autotrophic growth (HSM plus 5% CO2) or acetate for mixotrophic growth (TAP). This study was to elucidate the differential regulation of methionine sulfoxide reductase (MSR) gene expression between HSM plus 5% CO2 and TAP cultured cells, and also to determine the difference of gene expression in response to high light (1,000 £gE m-2 s-1). The role of photosynthetic electron transport (PET) in the regulation of MSR gene expression was also examined by the use of PET inhibitors. High light inhibited PSII activity (Fv/Fm and Fv'/Fm') of HSM plus 5% CO2 and TAP cultured cells., while the responses of CrMSR gene expression in mixotrophically grown cells were different from autotrophically grown cells, High light increased the expression of CrMSRA1, CrMSRA2, CrMSRA3, CrMSRA5, CrMSRB1.2, and CrMSRB2.1, but inhibited the expression of CrMSRA4 and CrMSRB2.2 in autotrophically grown cells. The expression of CrMSRA3, CrMSRA5, and CrMSRB2.1 in mixotrophically grown cells was increased by high light but that of CrMSRA1, CrMSRA4, and CrMSRB2.2 was inhbited. The number of MSR isoform that was up-regulated by high light was greater in autotrophically grown cell than that in mixotrophically grown cells. Using the PET inhibitors (3-(3,4-dichlorophenyl)-1,1- dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB)), most of the CrMSRA expression was regulated by reduced QA for autotrophically grown cells while reduced PQ was the main site for mixotrophically grown cells by high light. The expression of CrMSRB in autotrophically grown cells was mainy modulated by QA (-) or Cytb6f (-), while that was not affected by PET, except a role of Cytb6f (-) on the high light-induced CrMSRB2.2 expression. We fouind that CrMSRB gene expression in autotrophically grown cells was highly affected by PET but not for micotrophically grtown cells. The present result that H2O2 did not accumulate in autotrophically and mixotrophically grown cells suggests that H2O2 may be not involved in the regulation of high light regulation of CrMSR gene expression. The present study shows that the mRNA expression of CrMSR isoforms in Chlamydomonas was diffrerentially regulated between autotrophically and mixttrophically grown cells. The relationship between the utilization of different C source and CrMSR gene expression will be discussed.

Eddy-covariance (EC) CO₂ flux data were analysed and annual carbon (C) balances estimated for a four-year period (2004-2007) following clearcut harvesting of a boreal jack pine stand in northern Saskatchewan. The site was a source of C to the atmosphere for all years, with annual net ecosystem productivity (NEP) increasing from -153 g C m⁻² yr⁻¹ in 2004 to -63 g C m⁻² yr⁻¹ in 2007. This increase was mainly due to gross primary productivity (GPP) increasing significantly from 78 to 200 g C m⁻² yr⁻¹ , while ecosystem respiration (R) increased only slightly from 231 to 263 g C m⁻² yr⁻¹ over the same period. In the 2006 growing season (GS), a field campaign was conducted to investigate the relationships between monthly destructive measurements of leaf area index (LAI) and daily measurements of the normalized difference vegetation index (NDVI) and photosynthetic capacity (Amax). The latter was derived from 5-day, 16-day, 30-day and annual Michaelis-Menten light response analyses using daytime measurements of NEP and incident photosynthetically active radiation. Digital-camera data were used to evaluate the potential of using the rectilinear-lens vegetation index (RLVI) as a surrogate for NDVI of a young forest stand. Results showed that LAI was linearly related to NDVI and RLVI, which was largely the result of changes in the deciduous vegetation component across the GS. These results indicate that RLVI could be used as a surrogate for NDVI up to a GS maximum LAI of 0.91 m2 m⁻² observed in 2006. Measured mean (± 1 S.D.) GS LAI was 0.67 (± 0.24) m² m⁻² in 2006. LAI accounted for the majority of the variability in Amax at the 30-day time scale, while at shorter time scales air temperature was the dominant control. For 2004 to 2007, mean spring estimates of LAI were 0.25, 0.29, 0.38 (compared to 0.40 m² m⁻² from measurements) and 0.41 m² m⁻², respectively. Results suggest that a steady increase in the jack pine LAI component accounted for the annual increases in GPP and hence NEP over the four years.

The experimental objective. The study was designed to establish the effects of crop stand density and fertilization on spring rape productivity. Statements to be defended: 1. Crop stand density and plant supply with nutrients affect the penetration of photosynthetically active radiation to the soil surface and various heights of crop canopy. 2. Under favourable nutritional conditions, spring rape reaches the maximum photosynthetic productivity at flowering in a crop with a lower stand density; while under less favourable conditions, the maximum photosynthetic productivity at flowering is achieved in a crop with a higher stand density. 3. Under favourable nutritional conditions, at optimal crop stand density, spring rape accumulates the highest content of nutrients in the above-ground plant part at flowering stage. 4. In differently fertilized spring rape crops weed occurrence is determined by plant number per unit area, light regime and meteorological conditions. 5. Under favourable nutritional conditions, having formed an optimal spring rape crop, the plants become more resistant to the dark leaf and pod spot, verticillium wilt, sclerotrinia stem rot and rape stem pests; however, the crop remains susceptible to phoma stem canker. 6. Diverse photosynthetic conditions in differently fertilized spring rape crops differing in stand density determine formation of the above-ground and root mass of spring rape plants. 7. Spring rape yield formation depends on the number of... [to full text] / Tyrimų tikslas – nustatyti pasėlio tankumo ir tręšimo įtaką vasarinių rapsų pasėlio produktyvumui. Ginamieji disertacijos teiginiai: 1. Pasėlio tankumas ir augalų aprūpinimas maisto medžiagomis daro įtaką fotosintetiškai aktyvios radiacijos prasiskverbimui į dirvos paviršių ir įvairius vasarinių rapsų pasėlio ardus. 2. Palankiomis mitybos sąlygomis vasariniai rapsai fotosintezės produktyvumo maksimumą žydėjimo tarpsniu pasiekia retesniame pasėlyje, o augdami mažiau palankiomis – tankesniame pasėlyje. 3. Palankiomis mitybos sąlygomis esant optimaliam pasėlio tankumui vasariniai rapsai žydėjimo tarpsniu antžeminėje dalyje sukaupia didžiausią maisto medžiagų kiekį. 4. Skirtingai tręštuose vasarinių rapsų pasėliuose piktžolių plitimą lemia augalų skaičius ploto vienete, šviesos režimas ir meteorologinės sąlygos. 5. Palankiomis mitybos sąlygomis suformavus optimalų vasarinių rapsų pasėlį augalai tampa atsparesni juodosios dėmėtligės, verticiliozės, baltojo puvinio ir rapsų stiebų kenkėjų pažeidimams, tačiau išlieka jautrūs fomozės pažeidimams. 6. Nevienodos fotosintezės sąlygos skirtingai tręštuose, nevienodo tankumo vasarinių rapsų pasėliuose lemia vasarinių rapsų antžeminės ir šaknų masės formavimąsi. 7. Vasarinių rapsų derliaus formavimąsis priklauso nuo augalų skaičius ploto vienete bei jų aprūpinimo maisto medžiagomis. 8. Palankiomis mitybos sąlygomis didžiausias energetinis efektyvumas gaunamas retesniame vasarinių rapsų pasėlyje, o nepalankiomis – tankesniame.

<p>Elevated temperatures accompanying climate warming are expected to have adverse effects on sensitive lichen species. This premise was examined by measuring the sensitivity of different lichen species to elevated temperatures in the laboratory and in the field. Laboratory studies involved the exposure of nine hydrated lichen species (Xanthoparmelia austro-africana, X. hyporhytida, Xanthoparmelia sp., Xanthomaculina hottentotta, Teloschistes capensis, Ramalina sp., Flavopuntelia caperata, Lasallia papulosa, Parmotrema austrosinensis) collected from sites of different aridity and mean annual temperature for 2 hourly intervals to temperatures ranging from 24&ordm / C to 48&ordm / C in a forced daft oven and measuring their respiration rates and maximum quantum yield of PSII. Field studies involved simultaneous hourly measurements of ground surface air temperatures and Lichen effective quantum yield of PSII of hydrated lichen species populations under ambient and artificially modified environmental conditions.</p>