Laboratory tank studies of a single species of phytoplankton using a remote sensing fluorosensor

Phytoplankton were grown in the laboratory for the purpose of testing a remote fluorosensor. The fluorosensor uses a unique four-wavelength dye laser system to excite phytoplankton bearing chlorophyll and to measure the chlorophyll fluorescence generated by this excitation. Six different species were tested, one at a time, and each was grown two to four times. Fluorescence measured by the fluorosensor provides good quantitative measurement of chlorophyll concentrations for all species tested while the cultures were in log phase growth. Fluorescene cross section ratios obtained in the single species tank tests support the hypothesis that the shape of the fluorescence cross section curve remains constant with the species (differences in fluorescence cross section ratios are a basis for determining composition of phytoplankton according to color group when a multiwavelength source of excitation is used. Linear relationships exist between extracted chlorophyll concentration and fluorescence measured by the remote fluorosensor during the log phase growth of phytoplankton cultures tested

From chlorophyll a towards bacteriochlorophyll a: Excited-state processes of modified pigments

By means of fluorescence spectroscopy and nonlinear absorption experiments, excited-state processes of the modified pigments [3-acetyl]-chlorophyll a, [31-OH]-bacteriochlorophyll a and [3-vinyl]-bacteriochlorophyll a were investigated and compared with those of chlorophyll a and bacteriochlorophyll a

Leaf Scattering Polarimetry and Chlorophyll Fluorescence

© 2019 Published by Elsevier Ltd. This is an open access article under the CC BY license. (http://creativecommons.org/licenses/by/4.0/).A number of spectropolarimetry measurements on leaves using white light and narrow band illumination have been reported in recent years because of interest in signatures for remote sensing of exoplanet life. Chlorophyll fluorescence occurs in white light illuminated experiments and is known to be polarised and so might contaminate surface scattering measurements. A displacing filter experiment was performed on the leaves of two common plants, Ficus benjamina and Chamaedorea elegans, to estimate the contribution of chlorophyll fluorescence in the spectropolarimetry of leaf scattering and transmission. Chlorophyll fluorescence is present as a measurable polarised component of up to 15% of scattered and transmitted light for the leaf samples. Other effects emerged which indicate that in vivo measurements on leaves are subject to the responsive nature of the leaves to changes in colour and intensity of the incident light.Peer reviewe

Aplications of Laser Induced Chlorophyll Fluorescence Imaging to detect Environmental Effect on Spinach Plant

Laser Induced Chlorophyll Fluorescence spectroscopy has been developed and used for many years and recently becomes a promising nondestructive method to detect early symptoms of environmental stresses on plants. An affordable, portable, and effective system of Laser Induced Chlorophyll Fluorescence detection needs to be developed that can be used by most farmers. In this research, a system of chlorophyll fluorescence imaging which consisted of some light sources, some optical components, samples, a CMOS camera as a detector has been applied to detect the effect of sunlight intensity variation on plants of Amaranthus tricolor spinach. The spinach plants were treated by the sunlight intensity variation after 10 days growth. The samples were the detached spinach leaves grown under three sunlight intensity variations and the spinach leaf extract in ethanol grown under two sunlight intensity variations. The detached leaf samples were taken for investigation after 10 days and 18 days treatments. There were 5 plant samples for each treatment. The spinach extraction samples was taken from different spinach plants after 20 day treatment. The variations of sunlight were 90 % using one layer of plastic cover, 40% using a layer of plastic and a layer of dark net cover, and 32 % using two layers of dark net cover, compared to sunlight intensity without cover. Diode lasers and LEDs with different wavelength were used as light sources, performances of both were compared. The detached leaves and the spinach extract in a cuvette were illuminated by laser and LED light and their images were recorded by the CMOS camera. The fluorescence intensities were represented by the maximum intensities of RGB values found from RGB plot using ImageJ software. The research results showed that wavelength diode lasers and LEDS that can give significant differences in the three treatments were 680 nm for LED and 780 nm for diode laser for detached leaf experiment. The 680 nm LED and the 780 nm diode laser, respectively, gave 24.3 % and 29 % different in fluorescence intensities between 90% and 32 % sunlight intensity treatments. The 525 nm LED and 532 nm diode laser did not give significant difference for all treatments. The fluorescence intensities were higher for 525 nm LED 532 nm diode laser than those for 680 nm LED and 780 nm laser because the chlorophyll absorbed more light in NIR wavelength. The fluorescence intensities were higher at 10 day treatment that at 18 day treatment. It could be because the plants had much less chlorophyll since the optimum growth of the spinach is 25 days. The leaf extract method gave better spectrum visualization however it could not differentiate both treatments significantly except at 680 nm wavelengths. Both diode laser and LEDS have the possibilities to be used as the low cost light source for chlorophyll fluorescence imaging

High-resolution methods for fluorescence retrieval from space

The retrieval from space of a very weak fluorescence signal was studied in the O2A and O2B oxygen atmospheric absorption bands. The accuracy of the method was tested for the retrieval of the chlorophyll fluorescence and reflectance terms contributing to the sensor signal. The radiance at the top of the atmosphere was simulated by means of a commercial radiative-transfer program at a high resolution (0.1 cm-1). A test data set was generated in order to simulate sun-induced chlorophyll fluorescence at the top of the canopy. Reflectance terms were spectrally modeled using cubic splines and fluorescence by means of the sum of two Voigt functions. Sensor radiance residual minimization was performed in the presence of a multiplicative noise, thus ensuring that the sensor simulations were realistic. The study, which focused on the possibility of retrieving fluorescence with an accuracy better than 10%, was performed for instrument resolutions ranging from about 0.4 cm-1 to 2 cm-1 in order to test the algorithm for the characteristics of existing and planned hyper-spectral sensors. The algorithm was also used to retrieve fluorescence in the single O2A band at the OCO and TANSO-FTS instrument spectral resolution

Effects of short-term low temperature stress on chlorophyll fluorescence transients in Antarctic lichen species

Chlorophyll fluorescence is an effective tool for investigating characteristics of any photosynthesizing organisms and its responses due to different stressors. Here, we have studied a short-term temperature response on two Antarctic green algal lichen species: Umbilicaria antarctica, and Physconia muscigena. We measured slow chlorophyll fluorescence transients in the species during slow a cooling of thallus temperature from 20°C to 5°C with a 10 min. acclimation at each temperature in dark. The measurements were supplemented with saturation pulses for the analysis of chlorophyll fluorescence parameters: maximum yield of PS II photochemistry (FV/FM), effective quantum yield of PS II photochemistry (FPSII) and non-photochemical quenching (NPQ). In response to decreasing thallus temperature, we observed species-specific changes in chlorophyll fluorescence levels P, S, M, T reached during chlorophyll fluorescence transient as well as in the shape of the chlorophyll fluorescence transients. With a decrease in temperature, the time at which M and T chlorophyll fluorescence levels were reached, increased. These changes were attributed to redox state of plastoquinon pool, changes in Calvin-Benson cycle activity, non-photochemical quenching components, state transition in particular. In this study, we present some chlorophyll fluorescence ratios (P/M, M/T, P/T) and chlorophyll fluorescence increase rates (FR1, i.e. O to P, and FR2 - i.e. S to M) as the parameters reflecting direct temperature effects on chloroplastic apparatus of lichen alga sensitively. We proposed that species-specific changes in the slow phase of chlorophyll fluorescence transients could be potentially used as indicators of low temperature effects in photosynthetic apparatus of lichen algal photobionts. Interspecific differences in response to low temperature might be evaluated using the approach as well

An algorithm for computing chlorophyll-a concentrations using a dual-frequency fluorosensor

An algorithm to be used on data from a dual-frequency fluorosensor (i.e. one using two wavelengths for excitation of chlorophyll-a fluorescence) to compute total chlorophyll-a concentration and to partition that chlorophyll between two color groups present in a mixed phytoplankton population is described. The algorithm is based on laboratory and field-testing experience gained with the airborne lidar oceanographic probing experiment fluorosensor

Features of chlorophyll fluorescence transients can be used to investigate low temperature induced effects on photosystem II of algal lichens from polar regions

Chlorophyll fluorescence is an effective tool for investigating characteristics of any photosynthesizing organisms and its responses due to different stressors. Here, we have studied a short-term temperature response on three Antarctic green algal lichen species: Umbilicaria antarctica, Xanthoria elegans, and Rhizoplaca melanophtalma. We measured slow chlorophyll fluorescence transients in these Antarctic lichen species during slowely cooling of thallus temperature from 20°C to 5, 0 and -5°C with 20 minute acclimation at each temperature. The measurements were supplemented with saturation pulses for the analysis of chlorophyll fluorescence parameters: maximum yield of PS II photochemistry (FV/FM), effective quantum yield of PS II photochemistry ( Phi PSII) and quenching parameters. In response to decreasing thallus temperature, we observed species-specific changes in chlorophyll fluorescence parameters as well as in the shape of the chlorophyll fluorescence transients. We propose that species-specific changes in the slow phase of chlorophyll fluorescence transients can be potentially used as indicators of freezing stress in photosynthetic apparatus of lichen algal photobionts.Využití pomalé indukční kinetiky fluorescence chlorofylu a parametrů z ní odvozených pro výzkum teplotního stresu u tří druhů lišejníků: Umbilicaria antarctica, Xanthoria elegans, a Rhizoplaca melanophtalma.Chlorophyll fluorescence is an effective tool for investigating characteristics of any photosynthesizing organisms and its responses due to different stressors. Here, we have studied a short-term temperature response on three Antarctic green algal lichen species: Umbilicaria antarctica, Xanthoria elegans, and Rhizoplaca melanophtalma. We measured slow chlorophyll fluorescence transients in these Antarctic lichen species during slowely cooling of thallus temperature from 20°C to 5, 0 and -5°C with 20 minute acclimation at each temperature. The measurements were supplemented with saturation pulses for the analysis of chlorophyll fluorescence parameters: maximum yield of PS II photochemistry (FV/FM), effective quantum yield of PS II photochemistry (Phi PSII) and quenching parameters. In response to decreasing thallus temperature, we observed species-specific changes in chlorophyll fluorescence parameters as well as in the shape of the chlorophyll fluorescence transients. We propose that species-specific changes in the slow phase of chlorophyll fluorescence transients can be potentially used as indicators of freezing stress in photosynthetic apparatus of lichen algal photobionts