In situ study of photoinhibition of photosynthesis and xanthophyll cycle activity in plants growing in natural gaps of the tropical forest

1998 ◽  
Vol 25 (2) ◽  
pp. 189 ◽  
Author(s):  
A. Thiele ◽  
G.H. Krause ◽  
K. Winter
Keyword(s):  
Chlorophyll A ◽  
Xanthophyll Cycle ◽  
Fluorescence Emission ◽  
D1 Protein ◽  
Barro Colorado Island ◽  
Slow Phase ◽  
Photoinhibition Of Photosynthesis ◽  
Total Carotenoids ◽  
Lowland Forest

Photoinhibition of photosynthesis was studied in situ in leaves of several species of plants growing in natural treefall gaps of a tropical lowland forest (Barro Colorado Island, Panama). Leaves showed several features typical of sun-acclimation: relatively high pools of total carotenoids and xanthophyll cycle pigments and high ratios of chlorophyll a to b. During 1–2 h periods of exposure to direct mid-day sun, all leaves experienced substantial photoinhibition as indicated by a marked decline in the ratio of variable to maximum chlorophyll a fluorescence emission, FV/FM, detected after 10 min of dark adaptation. After return to shade, these ‘dark-adapted’ FV/FM ratios increased with biphasic kinetics, similar to previous findings under controlled conditions in the laboratory. A phase lasting about 1 h accounted for most of the recovery of FV/FM and was followed by a slow phase which proceeded until sunset. The decline in FV/FM during photoinhibition and the fast phase of recovery correlated closely with the amounts of zeaxanthin in the leaves. Given the small portion of the second recovery phase which has previously been attributed to turnover of the D1 protein in Photosystem II, high xanthophyll cycle activity in these gap leaves is probably responsible for the major part of photoinhibition, providing an efficient energy dissipation pathway during periods of high sunlight exposure.

scholarly journals Performance of a Handheld Chlorophyll-a Fluorometer: Potential Use for Rapid Algae Monitoring

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1409
Author(s):  
Hamdhani Hamdhani ◽  
Drew E. Eppehimer ◽  
David Walker ◽  
Michael T. Bogan
Keyword(s):  
Chlorophyll A ◽  
Surface Waters ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Water Quality Monitoring ◽  
Ambient Light ◽  
Calibration Equation ◽  
Field Samples ◽  
Potential Use

Chlorophyll-a measurements are an important factor in the water quality monitoring of surface waters, especially for determining the trophic status and ecosystem management. However, a collection of field samples for extractive analysis in a laboratory may not fully represent the field conditions. Handheld fluorometers that can measure chlorophyll-a in situ are available, but their performance in waters with a variety of potential light-interfering substances has not yet been tested. We tested a handheld fluorometer for sensitivity to ambient light and turbidity and compared these findings with EPA Method 445.0 using water samples obtained from two urban lakes in Tucson, Arizona, USA. Our results suggested that the probe was not sensitive to ambient light and performed well at low chlorophyll-a concentrations (<25 µg/L) across a range of turbidity levels (50–70 NTU). However, the performance was lower when the chlorophyll-a concentrations were >25 µg/L and turbidity levels were <50 NTU. To account for this discrepancy, we developed a calibration equation to use for this handheld fluorometer when field monitoring for potential harmful algal blooms in water bodies.

Response of Lake Michigan Benthic Algae to in situ Enrichment with Si, N, and P

1988 ◽  
Vol 45 (2) ◽  
pp. 271-279 ◽  
Author(s):  
Hunter J. Carrick ◽  
Rex L. Lowe
Keyword(s):  
Chlorophyll A ◽  
Algal Biomass ◽  
Lake Michigan ◽  
Benthic Algae ◽  
Benthic Diatoms ◽  
Nearshore Area

The possibility that benthic algae in the nearshore area of Lake Michigan might be growth limited by Si was tested using nutrient-releasing substrata. Nutrient treatments were Si, N + P, Si + N + P, and controls (CONT) and were sampled after 7, 14, and 31 d of exposure. Addition of Si alone had little stimulatory effect on algal biomass, while enrichment with Si + N + P led to the greatest increase in chlorophyll a, particulate Si, total biovolume, and diatom biovolume after 14 d of incubation (P < 0.0001). By day 31, communities on CONT and Si substrata exhibited little change in biomass and remained dominated by diatoms (98% of total biovolume), while algal biomass on both N + P and Si + N + P substrata increased more than eightfold (P < 0.0001) and consisted mainly of Stigeoclonium tenue (Chlorophyta) and Schizothrix calcicolas (Cyanophyta). These results indicate that benthic diatoms in Lake Michigan are not currently limited by Si, but may become Si limited following enrichment with N + P.

scholarly journals Temporal Variation of Chlorophyll-a Concentrations in Highly Dynamic Waters from Unattended Sensors and Remote Sensing Observations

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2699 ◽  
Author(s):  
Jian Li ◽  
Liqiao Tian ◽  
Qingjun Song ◽  
Zhaohua Sun ◽  
Hongjing Yu ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Quality ◽  
Chlorophyll Fluorescence ◽  
Chlorophyll A ◽  
Temporal Variations ◽  
Lake Area ◽  
Short Term ◽  
Chl A ◽  
Spatio Temporal

Monitoring of water quality changes in highly dynamic inland lakes is frequently impeded by insufficient spatial and temporal coverage, for both field surveys and remote sensing methods. To track short-term variations of chlorophyll fluorescence and chlorophyll-a concentrations in Poyang Lake, the largest freshwater lake in China, high-frequency, in-situ, measurements were collected from two fixed stations. The K-mean clustering method was also applied to identify clusters with similar spatio-temporal variations, using remote sensing Chl-a data products from the MERIS satellite, taken from 2003 to 2012. Four lake area classes were obtained with distinct spatio-temporal patterns, two of which were selected for in situ measurement. Distinct daily periodic variations were observed, with peaks at approximately 3:00 PM and troughs at night or early morning. Short-term variations of chlorophyll fluorescence and Chl-a levels were revealed, with a maximum intra-diurnal ratio of 5.1 and inter-diurnal ratio of 7.4, respectively. Using geostatistical analysis, the temporal range of chlorophyll fluorescence and corresponding Chl-a variations was determined to be 9.6 h, which indicates that there is a temporal discrepancy between Chl-a variations and the sampling frequency of current satellite missions. An analysis of the optimal sampling strategies demonstrated that the influence of the sampling time on the mean Chl-a concentrations observed was higher than 25%, and the uncertainty of any single Terra/MODIS or Aqua/MODIS observation was approximately 15%. Therefore, sampling twice a day is essential to resolve Chl-a variations with a bias level of 10% or less. The results highlight short-term variations of critical water quality parameters in freshwater, and they help identify specific design requirements for geostationary earth observation missions, so that they can better address the challenges of monitoring complex coastal and inland environments around the world.

scholarly journals SENSITIVITY TO ENVIRONMENTAL STRESS OF PRATA,JAPIRA AND VITÓRIA BANANA CULTIVARS PROVEN BY CHLOROPHYLL a FLUORESCENCE

2017 ◽  
Vol 39 (2) ◽  
Author(s):  
PRISCILA NOBRES DOS SANTOS ◽  
DIOLINA MOURA SILVA ◽  
CAMILLA ZANOTTI GALLON ◽  
JOSÉ AIRES VENTURA
Keyword(s):  
Environmental Stress ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Physiological Responses ◽  
Fluorescence Emission ◽  
Conservation Of Energy ◽  
Post Harvest ◽  
Mda Content ◽  
Two Stages

ABSTRACT This study aimed to evaluate the physiological responses to environmental stress during pre- and post-harvest of the following banana cultivars: Prata (AAB), Japira (AAAB) and Vitoria (AAAB). Analyses were carried out on young plants at vegetative stage (daughter-plant) and adult plants at reproductive stage (motherplant). The experimental design was completely randomized. In the in vivo pre-harvest analysis were used seven replications, in a factorial scheme (3x2x2), three cultivars and two stages (vegetative and reproductive) and two collection periods (March and June). For the analysis of post-harvest quality were used five replications in a factorial design (3x2x5), corresponding to three cultivars, two development stages and five periods of post-harvest analysis, carried out every two days from stage 4 of fruit ripening. The chlorophyll a fluorescence emission kinetics showed low photochemical performance of the three cultivars in June, a period characterized by lower temperatures and water deficit. Prata was the cultivar with the lowest tolerance to abiotic physiological behavior changes, which also reflected in fruit quality, because there was a change in physical and physicochemical parameters. Japira and Vitoria cultivars showed similar physiological responses in the pre- and post-harvest periods, according to their phylogenetic proximity. The total performance index, i.e., the conservation of energy absorbed by PSII up to the reduction of the final PSI acceptors (PItotal) and the di-malonic aldehyde (MDA) content were significantly higher in Japira and Vitoria cultivars compared to Prata cultivar in the reproductive phase. There was no significant change in the potential quantum efficiency of PSII (FV / FM = jP0) among the three cultivars. It was concluded that Japira and Vitoria cultivars showed greater plasticity to tolerate or even adapt to abiotic variations keeping higher fruit yield. PItotal is the most sensitive parameter during the banana life cycle and important tool for distinguishing different cultivars yields.

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