scholarly journals Solar‐induced chlorophyll fluorescence and short‐term photosynthetic response to drought

2020 ◽  
Vol 30 (5) ◽  
Author(s):  
Levi T. Helm ◽  
Hanyu Shi ◽  
Manuel T. Lerdau ◽  
Xi Yang
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosynthetic Response ◽  
Short Term

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 Photosynthetic response to nitrogen source and different ratios of nitrogen and phosphorus in toxic cyanobacteria, Microcystis aeruginosa FACHB-905

2016 ◽  
Author(s):  
Guotao Peng ◽  
Zhengqiu Fan ◽  
Xiangrong Wang ◽  
Chen Chen
Keyword(s):  
Chlorophyll Fluorescence ◽  
Algal Blooms ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Photosynthetic Response ◽  
Nitrogen And Phosphorus ◽  
Ammonium Toxicity ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
N Assimilation

<p>The frequent outbreak of cyanobacterial blooms has become a worldwide phenomenon in freshwater ecosystems. Studies have elucidated the close relationship between harmful algal blooms and nutrient contents, including the loading of nitrogen and the ratios of nitrogen (N) and phosphorus (P). In this study, the effect of inorganic (nitrate and ammonium) and organic (urea) nitrogen at varied N/P ratios on the <em>Microcystis</em> <em>aeruginosa</em> FACHB-905 accumulation and photosynthesis was investigated.  The optimal NO<sub>3</sub>/P in this study were 30~50 indicated by the cell abundance (4.1×10<sup>6</sup>/mL), pigment concentration (chlorophyll a 3.1 mg/L,  phycocyanin 8.3mg/L), and chlorophyll fluorescence parameters (<em>rETR</em>, <em>E<sub>k</sub>, α, φPSII</em> and <em>F<sub>v</sub>/F<sub>m</sub> </em>values), while too high NO<sub>3</sub>-N (N/P=100:1) would cause an intracellular nitrate inhibition, leading to a decrease of photosynthetic activity. In addition, low concentration of NH<sub>4</sub>-N (N/P=4:1) would favor the <em>M. aeruginosa </em>growth and photosynthesis, and high NH<sub>4</sub>/P ratio (&gt;16) would rise the ammonium toxicity of algal cells and affect the N assimilation. In urea treatments, <em>M. aeruginosa </em>responded similarly to the NH<sub>4</sub>-N treatments both in growth curves and pigment contents, and the favorable N/P ratio was between 16~30, suggested by the chlorophyll fluorescence parameters. The results demonstrated that the various chemical forms of N and N/P ratios have a significant impact on <em>Microcystis</em> abundance and photosynthesis. More work is needed to figure out the mechanism of nitrogen utilization by <em>Microcystis</em> and  the photosynthetic response to nutrient stress at the molecular level.</p>

Temperature response of dry matter accumulation, leaf photosynthesis, and chlorophyll fluorescence in an old and a new maize hybrid during early development

1991 ◽  
Vol 71 (2) ◽  
pp. 353-359 ◽  
Author(s):  
M. Tollenaar ◽  
M. Mihajlovic ◽  
A. Aguilera
Keyword(s):  
Chlorophyll Fluorescence ◽  
Low Temperature ◽  
Dry Matter ◽  
Temperature Tolerance ◽  
Dry Matter Accumulation ◽  
Leaf Photosynthesis ◽  
Short Term ◽  
Dry Matter Partitioning ◽  
Leaf Stage ◽  
Low Temperature Tolerance

Studies were conducted to investigate whether genetic improvement in dry matter accumulation of maize (Zea mays L.) hybrids recommended in Ontario from the late 1950s to the late 1980s is associated with cold-temperature tolerance during early phases of development. The maize hybrids Pride 5 (released in 1959) and Pioneer 3902 (released in 1988) were compared at 16/7, 23/14, and 33/24 °C under a 16-h photoperiod with a photosynthetic photon flux density of 650 μmol m−2 s−1 in long-term and short-term temperature experiments conducted in controlled-environment cabinets. In the long-term temperature experiment, plants were grown at the three temperature regimes from the 4- to the 12-leaf stage. Total and plant component dry matter was determined at the 8-, 10-, and 12-leaf stage, and leaf photosynthesis and chlorophyll fluorescence were measured at the 10-leaf stage. In the short-term temperature experiment, plants were exposed to the three temperature regimes during a 3-d period after the 9-leaf stage, followed by 2 d at 23/14 °C. Dry matter accumulation during the 5-d period was measured and leaf photosynthesis and chlorophyll fluorescence were measured during each of the last 3 d of the 5-d period. Results showed a highly significant temperature effect on all measured parameters. Dry matter of Pride 5 at the 10-leaf stage was higher than that of Pioneer 3902, but rates of dry matter accumulation and leaf photosynthesis did not differ among hybrids, and hybrid × temperature interactions were not significant for these parameters. Hybrid × temperature interactions were significant for dry matter partitioning and the fluorescence parameter Fv/Fm, suggesting better low-temperature tolerance for Pride 5. Results of the short-term temperature study showed a significant hybrid × temperature interaction for dry matter accumulation, with Pride 5 higher than Pioneer 3902 at the low temperature regime and Pride 5 lower than Pioneer 3902 at the high temperature regime. Results of these experiments suggest that improvement over the past 30 yr of Ontario maize hybrids is not associated with improved low-temperature tolerance during early development. Key words: Maize, low-temperature tolerance, dry matter accumulation, dry matter partitioning, photosynthesis, chlorophyll fluorescence

Effect of short-term girdling on stomatal conductance and chlorophyll fluorescence inAlhagi sparsifolia

2014 ◽  
Vol 34 (23) ◽  
Author(s):  
唐钢梁 TANG Gangliang ◽  
李向义 LI Xiangyi ◽  
林丽莎 LIN Lisha ◽  
李磊 LI Lei ◽  
鲁建荣 LU Jianrong
Keyword(s):  
Chlorophyll Fluorescence ◽  
Stomatal Conductance ◽  
Short Term

scholarly journals The effect of UV-B radiation on the chlorophyll fluorescence parameters of the husked and the naked oat

2013 ◽  
Vol 52 (1-2) ◽  
pp. 149-152 ◽  
Author(s):  
Elżbieta Skórska
Keyword(s):  
Chlorophyll Fluorescence ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Short Term ◽  
Chlorophyll Fluorescence Parameters ◽  
Naked Oat ◽  
Fluorescence Parameters ◽  
Traditional Variety

Naked oat variety of STH296 showed higher tolerance than traditional variety Bajka on short-term UV-B radiation (UV-B<sub>BE</sub>=1 1 kJ·m<sup>-2</sup>) on the stage of primary photosynthesis reaction recorded using chlorophyll fluorescence induction of the leaves.

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