scholarly journals Photosystem II (PSII) photochemical efficiency (Yield PSII) recorded at noon (ΔF/Fm') and at dusk (Fv/Fm) on random coral colonies of Orbicella faveolata from Varadero and Rosario reefs, Colombia, May 2017

2020 ◽  
Author(s):  
Mónica Medina ◽  
Roberto Iglesias-Prieto
Keyword(s):  
Photosystem Ii ◽  
Photochemical Efficiency ◽  
Orbicella Faveolata ◽  
Psii Photochemical Efficiency

Effects of heat stress on gas exchange and photosystem II (PSII) photochemical activity of Phillyrea angustifolia exposed to elevated CO2 and subsaturating irradiance

Botany ◽  
2008 ◽  
Vol 86 (4) ◽  
pp. 435-441 ◽  
Author(s):  
Luca Vitale ◽  
Carmen Arena ◽  
Amalia Virzo De Santo ◽  
Nicola D’Ambrosio
Keyword(s):  
Heat Stress ◽  
Electron Transport ◽  
Gas Exchange ◽  
Photosystem Ii ◽  
Photochemical Efficiency ◽  
Calvin Cycle ◽  
Fluorescence Measurements ◽  
Significant Difference ◽  
Psii Photochemical Efficiency ◽  
Phillyrea Angustifolia

Gas exchange and chlorophyll a fluorescence measurements were performed simultaneously on leaves of Phillyrea angustifolia L. to assess the effects of heat stress (30 min at 40 °C) on photosynthesis and photosystem II (PSII) photochemical efficiency of plants grown at ambient CO2 and exposed to an elevated CO2 concentration (800 µmol·mol–1) and 300 µmol photons·m–2·s–1. No significant difference was found in the heat-induced decreases of net photosynthesis (PN), quantum yield of PSII electron transport (ΦPSII), and maximum PSII photochemical efficiency (Fv/Fm) between plants exposed to ambient and elevated CO2 concentrations, showing that elevated CO2 was not able to reduce the potential for photoinhibition at high temperatures under moderate light conditions. The heat-induced decrease of PN was higher than that of ΦPSII indicating that reductive power was more utilized in non-assimilatory processes than in CO2 fixation at both CO2 treatments. This result suggested that impairment of the Calvin cycle rather than electron transport inhibition was the main cause of the limitation in CO2 fixation.

scholarly journals Biomass accumulation, photochemical efficiency of photosystem II, nutrient contents and nitrate reductase activity in young rosewood plants (Aniba rosaeodora Ducke) submitted to different NO3-:NH4+ ratios

2007 ◽  
Vol 37 (4) ◽  
pp. 533-541 ◽  
Author(s):  
Denize Caranhas de Sousa Barreto ◽  
José Francisco de Carvalho Gonçalves ◽  
Ulysses Moreira dos Santos Júnior ◽  
Andreia Varmes Fernandes ◽  
Adriana Bariani ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Nitrate Reductase ◽  
Growth Performance ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Photochemical Efficiency ◽  
Biomass Accumulation ◽  
Nitrate Content ◽  
Chl A ◽  
Culture Substrate

The rosewood (Aniba rosaeodora Ducke) is a native tree species of Amazon rainforest growing naturally in acidic forest soils with reduced redox potential. However, this species can also been found growing in forest gaps containing oxide soils. Variations in the forms of mineral nitrogen (NO3- or NH4+) may be predicted in these different edaphic conditions. Considering that possibility, an experiment was carried out to analyze the effects of different NO3-:NH4+ ratios on the growth performance, mineral composition, chloroplastid pigment contents, photochemical efficiency photosystem II (PSII), and nitrate redutase activity (RN, E.C.1.6.6.1) on A. rosaeodora seedlings. Nine-month-old seedlings were grown in pots with a washed sand capacity of 7.5 kg and submitted to different NO3-:NH4+ ratios (T1 = 0:100%, T2 = 25:75%, T3 = 50:50%, T4 = 75:25%, and T5 = 100:0%). The lowest relative growth rate was observed when the NO3-:NH4+ ratio was equal to 0:100%. In general, high concentrations of NO3- rather than NH4+ favored a greater nutrient accumulation in different parts of the plant. For the chloroplastid pigment, the highest Chl a, Chl b, Chl tot, Chl a/b and Chl tot/Cx+c contents were found in the treatment with 75:25% of NO3-:NH4+, and for Chl b and Cx+c it was observed no difference. In addition, there was a higher photochemical efficiency of PSII (Fv/Fm) when high NO3- concentrations were used. A linear and positive response for the nitrate reductase activity was recorded when the nitrate content increased on the culture substrate. Our results suggest that A. rosaeodora seedlings have a better growth performance when the NO3- concentrations in the culture substrate were higher than the NH4+ concentrations.

scholarly journals Response of common buckwheat and Tartary buckwheat from different elevations to selenium treatment

Fagopyrum ◽  
2021 ◽  
Vol 38 (1) ◽  
pp. 15-23
Author(s):  
Aleksandra Golob ◽  
Neja Luzar ◽  
Mateja Germ
Keyword(s):  
Photosystem Ii ◽  
Photochemical Efficiency ◽  
Morphological Characteristics ◽  
Tartary Buckwheat ◽  
Control Group ◽  
Common Buckwheat ◽  
Biochemical Characteristics ◽  
Selenium Treatment ◽  
Uv Absorbing Compounds ◽  
Effective Photochemical Efficiency

Common buckwheat and Tartary buckwheat were grown in Slovenia outdoors at different elevations – 300 m, 600 m and 1180 m a.s.l. Both species were foliarly treated with selenium twice (in the vegetative phase and in the flowering phase). The effects of Se treatment and different growing locations on selected biochemical, physiological and anatomical traits were monitored. In Se treated common buckwheat, amount of chlorophylls was higher in plants from Ljubljana (the lowest elevation – 300 m a.s.l.) than in plants grown in Podbeže (600 m a.s.l.), whereas in control group, plants grown in Ljubljana contained more chlorophylls than plants from Javorje (the highest elevation – 1180 m a.s.l.). In both buckwheat species, Se alone did not affect amount of chlorophylls in any of location. In Se treated common buckwheat plants, the amount of UV absorbing compounds was the highest in plants, grown at the highest elevation. In common buckwheat, Se lowered the number of CaOx in plants, grown in Javorje. Conditions at different elevations, as well as treatments with Se, did not affect potential and effective photochemical efficiency of Photosystem II. Keywords: common buckwheat, Tartary buckwheat, elevation, selenium, morphological characteristics, biochemical characteristics

scholarly journals Progesterone increases photochemical efficiency of photosystem II in wheat under heat stress by facilitating D1 protein phosphorylation

2017 ◽  
Vol 55 (4) ◽  
pp. 664-670 ◽  
Author(s):  
R. L. Xue ◽  
S. Q. Wang ◽  
H. L. Xu ◽  
P. J. Zhang ◽  
H. Li ◽  
...  
Keyword(s):  
Heat Stress ◽  
Photosystem Ii ◽  
Protein Phosphorylation ◽  
Photochemical Efficiency ◽  
D1 Protein

Effect of Juglone from C.cathayensis Exocarp on Summer Peony Photoinhibition

2012 ◽  
Vol 518-523 ◽  
pp. 189-193
Author(s):  
Xiang Ming Chen ◽  
Song Jin
Keyword(s):  
Stomatal Conductance ◽  
Photochemical Efficiency ◽  
Utilization Rate ◽  
Control Group ◽  
Photosynthetic System ◽  
Research Results ◽  
Photosynthesis Inhibition ◽  
Time Period ◽  
Light Utilization ◽  
Psii Photochemical Efficiency

This paper studies the effects of the Juglone on improving the photosynthesis of the peony growing in the summer field, and alleviating the photosynthesis inhibition in the two months of July and August, by using the 0.06mg/L Juglone extracted from the C.cathayensis exocarp, one kind of the forestry waste, to insufflate the peony leaf surface.The research results show that ,by comparing the peony leaf after procession with the control group, the Pn summit values of the photosynthetic rate improve by 10.5% and 12.8% respectively, and the photosynthesis noon-break is greatly shortened; the stomatal conductance variance of the leaf is not big, but the Ci content decreases significantly; the PSII photochemical efficiency of Fv/Fm reduces by 20% and 26% respectively; ΦPSII decreases by 18.1% and 19.9% respectively;between the time period 10 am and 1 pm, when the sunlight is the most sufficient, the contents of the chlorophyll qP decrease by 10% and 11.6% respectively,and the contents of the NPQ increase by 17.3% and 14.3% respectively. The research results show that Juglone could greatly reduce the summer sunlight harm on the photosynthetic system of the peony leaf chloroplast, and improve the light utilization rate of the peony leaf.

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