scholarly journals Seasonal Variation in Diurnal Photosynthesis and Chlorophyll Fluorescence of Four Genotypes of Cassava (Manihot esculenta Crantz) under Irrigation Conditions in a Tropical Savanna Climate

Agronomy ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 206 ◽  
Author(s):  
Supranee Santanoo ◽  
Kochaphan Vongcharoen ◽  
Poramate Banterng ◽  
Nimitr Vorasoot ◽  
Sanun Jogloy ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Quantum Yield ◽  
Rainy Season ◽  
Genotypic Variation ◽  
Effective Quantum Yield ◽  
Tropical Savanna ◽  
Psii Photochemistry ◽  
Diurnal Photosynthesis ◽  
Hot Season ◽  
Quantum Yield Of Psii

Photosynthesis performance during early vegetative growth is an important physiological trait determining yield of cassava, but limited information is currently available for the tropical savanna climate of Asia. Diurnal photosynthesis and chlorophyll fluorescence of the three-month-old plants of four commercial cassava genotypes (Rayong 9, RY9; Rayong 11, RY11; Kasetsart 50, KU50 and CMR38-125-77) grown under irrigation, were investigated in three seasons i.e., rainy, cool and hot. The mean daily net photosynthetic rate (Pn) across genotypes in the rainy season (11.75 µmolCO2/m2/s) was significantly lower than that in the cool season (14.60 µmolCO2/m2/s). Daily mean Pn in the hot season was 14.32 µmolCO2/m2/s. In the rainy season, maximum photochemical quantum yield of PSII (Fv/Fm) and effective quantum yield of PSII photochemistry (ΦPSII) were significantly higher than the other seasons, while electron transfer rate (ETR) and non-photochemical quenching (NPQ) were significantly lower. Genotypic variation was observed during the hot season in which RY11 had the highest and CMR38-125-77 the lowest mean daily Pn. The prominent mechanism to avoid damages from stress during afternoon in the hot season was to reduce leaf temperature by enhancing transpiration for RY11; to close stomata early for RY9, and to increase NPQ for CMR38-125-77.

scholarly journals Allelopathic effect of the Baltic picocyanobacterium Synechococcus sp. on selected diatoms

2017 ◽  
Author(s):  
Zofia Konarzewska ◽  
Sylwia Śliwińska-Wilczewska ◽  
Adam Latała
Keyword(s):  
Quantum Yield ◽  
Algal Blooms ◽  
Allelopathic Effect ◽  
Effective Quantum Yield ◽  
Fluorescence Parameters ◽  
Psii Photochemistry ◽  
Synechococcus Sp ◽  
The Baltic ◽  
Allelopathic Interactions ◽  
Quantum Yield Of Psii

It is commonly believed that the structure of phytoplankton and the formation of cyanobacterial and algal blooms may be explained by allelopathic interactions. The main aim of this study was to investigate the allelopathic effect of picocyanobacterium Synechococcus sp. on the following growth and fluorescence parameters: the maximum quantum yield of PSII photochemistry (Fv/Fm), and the effective quantum yield of PSII photochemistry (ΦPSII) of selected diatoms – Nitzschia fonticola, Fistulifera saprophila, Navicula perminuta and Amphora coffeaeformis. In this study, it was demonstrated that picocyanobacterium caused allelopathic effects against Baltic diatoms. The results showed that the addition of cell-free filtrate from Synechococcus sp. increased the number of cells of N. fonticola and F. saprophila. Moreover, it was found that picocyanobacterium was stimulated fluorescence parameters of N. fonticola, F. saprophila, and N. perminuta. On the other hand, it was noted that filtrate obtained from picocyanobacterium caused the inhibition of Fv/Fm parameter of A. coffeaeformis. The results of this experiment may provide further information about allelopathic interactions between Baltic picocyanobacteria and diatoms that are crucial to the understanding of algal blooms in aquatic ecosystems.

scholarly journals Physiological, morphological and anatomical leaf traits variation across leaf development in 'Corylus avellana'

2019 ◽  
Vol 40 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Rosangela Catoni ◽  
Francesco Bracco ◽  
Loretta Gratani ◽  
Mirko Umberto Granata
Keyword(s):  
Quantum Yield ◽  
Leaf Development ◽  
Leaf Traits ◽  
Corylus Avellana ◽  
Leaf Mass Per Area ◽  
Second Phase ◽  
Effective Quantum Yield ◽  
Maximum Quantum Yield ◽  
Psii Photochemistry ◽  
Quantum Yield Of Psii

The study analyzed the variations of physiological, morphological and anatomical leaf traits during its development in Corylus avellana L. saplings. Three different phases were identify during leaf development: the first phase (hereafter IP) considered in the developing leaves, the second phase (IIP) in the mature green leaves and the third phase (IIIP) in the senescent leaves. In particular, variations in parameters estimated from the photosynthetic light response curves, in chlorophyll fluorescence variables and in morphological leaf traits were analyzed during the three phases. The principal component analysis (PCA) carried out using all the considered morphological characters (leaf mass per area - LMA, and leaf tissue density - LTD) and physiological traits (the maximum net photosynthetic rates - ANmax, dark respiration rates - RD, light compensation point - LCP, light saturation point – LSP, maximum quantum yield - ɸmax, fluorescence-based maximum quantum yield of PSII photochemistry - Fv/FM and effective quantum yield of PSII photochemistry - ɸPSII) showed a complete separation among the considered phases. The results showed that the major differences occur between the phases IP and IIP. In particular, a greater variation was found for LMA, ANmax, RD. On the contrary a lower variation was observed for ɸmax which remain quite constant from IP to IIP indicating that chloroplasts present in juvenile leaves are fully functional.

Thermostability and Photostability of Photosystem II of the Resurrection Plant Haberlea rhodopensis Studied by Chlorophyll Fluorescence

2006 ◽  
Vol 61 (3-4) ◽  
pp. 234-240 ◽  
Author(s):  
Katya Georgieva ◽  
Liliana Maslenkova
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Quantum Yield ◽  
Photochemical Efficiency ◽  
Resurrection Plant ◽  
Haberlea Rhodopensis ◽  
Photochemical Efficiency Of Psii ◽  
Light Intensities ◽  
Psii Photochemistry ◽  
Quantum Yield Of Psii

The stability of PSII in leaves of the resurrection plant Haberlea rhodopensis to high temperature and high light intensities was studied by means of chlorophyll fluorescence measurements. The photochemical efficiency of PSII in well-hydrated Haberlea leaves was not significantly influenced by temperatures up to 40 °C. F0 reached a maximum at 50 °C, which is connected with blocking of electron transport in reaction center II. The intrinsic efficiency of PSII photochemistry, monitored as Fv/Fm was less vulnerable to heat stress than the quantum yield of PSII electron transport under illumination (ΦPSII). The reduction of ΦPSII values was mainly due to a decrease in the proportion of open PSII centers (qP). Haberlea rhodopensis was very sensitive to photoinhibition. The light intensity of 120 μmol m−2 s−1 sharply decreased the quantum yield of PSII photochemistry and it was almost fully inhibited at 350 μmol m−2 s−1. As could be expected decreased photochemical efficiency of PSII was accompanied by increased proportion of thermal energy dissipation, which is considered as a protective effect regulating the light energy distribution in PSII. When differentiating between the three components of qN it was evident that the energy-dependent quenching, qE, was prevailing over photoinhibitory quenching, qI, and the quenching related to state 1-state 2 transitions, qT, at all light intensities at 25 °C. However, the qE values declined with increasing temperature and light intensities. The qI was higher than qE at 40 °C and it was the major part of qN at 45 °C, indicating a progressing photoinhibition of the photosynthetic apparatus.

scholarly journals Protective Effects of Selenium on Wheat Seedlings under Salt Stress

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 272 ◽  
Author(s):  
Chiu-Yueh Lan ◽  
Kuan-Hung Lin ◽  
Wen-Dar Huang ◽  
Chang-Chang Chen
Keyword(s):  
Salt Stress ◽  
Chlorophyll Fluorescence ◽  
Energy Dissipation ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Physiological Traits ◽  
Effective Quantum Yield ◽  
Enzymatic Antioxidants ◽  
Wheat Seedlings ◽  
Chlorophyll Fluorescence Parameters

Wheat is a staple food worldwide, but its productivity is reduced by salt stress. In this study, the mitigative effects of 22 μM selenium (Se) on seedlings of the wheat (Triticum aestivum L.) cultivar Taichung SEL. 2 were investigated under different salt stress levels (0, 100, 200, 300, and 400 mM NaCl). Results of the antioxidative capacity showed that catalase (CAT) activity, non-enzymatic antioxidants (total phenols, total flavonoids, and anthocyanins), 1,1-Diphenyl-2-Picryl-Hydrazyl (DPPH) radical-scavenging activity, and the reducing power of Se-treated seedlings were enhanced under saline conditions. The more-stabilized chlorophyll fluorescence parameters (maximal quantum yield of photosystem II (Fv/Fm), minimal chlorophyll fluorescence (F0), effective quantum yield of photosystem II (ΦPSII), quantum yield of regulated energy dissipation of photosystem II (Y(NPQ)), and quantum yield of non-regulated energy dissipation of photosystem II (Y(NO)) and the less-extensive degradation of photosynthetic pigments (total chlorophyll and carotenoids) in Se-treated seedlings were also observed under salt stress. The elongation of shoots and roots of Se-treated seedling was also preserved under salt stress. Protection of these physiological traits in Se-treated seedlings might have contributed to stable growth observed under salt stress. The present study showed the protective effect of Se on the growth and physiological traits of wheat seedlings under salt stress.

scholarly journals Comparisons of Chlorophyll Fluorescence and Physiological Characteristics of Wheat Seedlings Influenced by Iso-Osmotic Stresses from Polyethylene Glycol and Sodium Chloride

Agronomy ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 325
Author(s):  
Chiu-Yueh Lan ◽  
Kuan-Hung Lin ◽  
Chun-Liang Chen ◽  
Wen-Dar Huang ◽  
Chang-Chang Chen
Keyword(s):  
Chlorophyll Fluorescence ◽  
Polyethylene Glycol ◽  
Sodium Chloride ◽  
Energy Dissipation ◽  
Quantum Yield ◽  
Photochemical Quenching ◽  
Effective Quantum Yield ◽  
Wheat Seedlings ◽  
Level 3 ◽  
Level 2

Wheat (Triticum aestivum) cultivar Taichung SEL.2 (TCS2) is a salt-tolerance variety, but the mechanism involved remains unclear. This study aims to distinguish between the non-ionic osmotic and salt-mediated physiological effects on TCS2. Osmotic agents polyethylene glycol (PEG) and sodium chloride (NaCl) were applied at three iso-osmotic levels, level 1 containing 24% (w/v) PEG and 200 mM NaCl, level 2 containing 26.5% (w/v) PEG and 250 mM NaCl), and level 3 containing 29% (w/v) PEG and 300 mM NaCl, respectively. According to the investigation of chlorophyll fluorescence in the better NaCl-treated seedlings, maximal quantum yield of photosystem II (PSII) (Fv/Fm) and significant higher effective quantum yield of PSII (ΦPSII) at level 3 were observed. Meanwhile, the non-photochemical quenching of PSII (NPQ) and the quantum yield of regulated energy dissipation of PSII [Y(NPQ)] were significantly higher in the NaCl-treated seedlings, and the quantum yield of non-regulated energy dissipation of PSII [Y(NO)] in the NaCl-treated seedlings was lower than the PEG-treated ones at level 2 and level 3. Furthermore, the less extensive degradation of photosynthetic pigments, the better ascorbate peroxidase (APX) activity and the less accumulation of malondialdehyde (MDA) were also observed in NaCl-treated seedlings. In the morphological traits, shoot elongation in NaCl-treated seedlings was also preserved. These results suggest that TCS2 is more resistant to NaCl-induced osmotic stress than to the PEG-induced stress. This study contributes to plant breeder interest in drought- and/or salt-tolerant wheat varieties.

scholarly journals Effect of Drought Stress on Chlorophyll Fluorescence Parameters, Phytochemical Contents, and Antioxidant Activities in Lettuce Seedlings

Horticulturae ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 238
Author(s):  
Yu Kyeong Shin ◽  
Shiva Ram Bhandari ◽  
Jung Su Jo ◽  
Jae Woo Song ◽  
Jun Gu Lee
Keyword(s):  
Ascorbic Acid ◽  
Chlorophyll Fluorescence ◽  
Drought Stress ◽  
Quantum Yield ◽  
Antioxidant Activities ◽  
Growth Parameters ◽  
Photochemical Quenching ◽  
Total Phenol Content ◽  
Effective Quantum Yield ◽  
Chlorophyll Fluorescence Parameters

This study monitored changes in chlorophyll fluorescence (CF), growth parameters, soil moisture content, phytochemical content (proline, ascorbic acid, chlorophyll, total phenol content (TPC), and total flavonoid content (TFC)), and antioxidant activities in 12-day-old lettuce (Lactuca sativa L.) seedlings grown under drought stress (no irrigation) and control (well irrigated) treatments in controlled conditions for eight days. Measurements occurred at two-day intervals. Among ten CF parameters studied, effective quantum yield of photochemical energy conversion in PSII (Y(PSII)), coefficient of photochemical quenching (qP), and coefficient of photochemical quenching of variable fluorescence based on the lake model of PSII (qL) significantly decreased in drought-stressed seedlings from day 6 of treatment compared to control. In contrast, maximum quantum yield (Fv/Fm), ratio of fluorescence (Rfd), and quantum yield of non-regulated energy dissipation in PSII (Y(NO)) were significantly affected only at the end. All growth parameters decreased in drought-stressed seedlings compared to control. Proline started increasing from day 4 and showed ~660-fold elevation on day 8 compared to control. Chlorophyll, ascorbic acid, TPC, TFC, and antioxidant activities decreased in drought-stressed seedlings. Results showed major changes in all parameters in seedlings under prolonged drought stress. These findings clarify effects of drought stress in lettuce seedlings during progressive drought exposure and will be useful in the seedling industry.

scholarly journals Ionic Homeostasis and Redox Metabolism Upregulated by 24-Epibrassinolide are Crucial for Mitigating Nickel Excess in Soybean Plants, Enhancing Photosystem II Efficiency and Biomass

2021 ◽  
Author(s):  
Marcelo Pires Saraiva ◽  
Camille Ferreira Maia ◽  
Bruno Lemos Batista ◽  
Allan Klynger da Silva Lobato
Keyword(s):  
Photosystem Ii ◽  
Membrane Damage ◽  
Effective Quantum Yield ◽  
Ionic Homeostasis ◽  
Nutrient Contents ◽  
Photosystem Ii Efficiency ◽  
Psii Photochemistry ◽  
Soybean Plants ◽  
Negative Impacts ◽  
Quantum Yield Of Psii

Abstract Nickel (Ni) excess often generates oxidative stress in chloroplasts, causing redox imbalance, membrane damage and negative impacts on biomass. 24-Epibrassinolide (EBR) is a plant growth regulator of great interest in the scientific community because it is a natural molecule extracted from plants that is biodegradable and environmentally friendly. This study aimed to determine whether EBR can induce benefits on ionic homeostasis and antioxidant enzymes and convey possible repercussions on photosystem II efficiency and biomass, more specifically evaluating nutritional, physiological, biochemical and morphological responses in soybean plants subjected to Ni excess. The experiment was randomized with four treatments, including two Ni concentrations (0 and 200 µM Ni, described as – Ni2+ and + Ni2+, respectively) and two concentrations of 24-epibrassinolide (0 and 100 nM EBR, described as – EBR and + EBR, respectively). In general, Ni caused deleterious modulatory effects on chlorophyll fluorescence and gas exchange. In contrast, EBR enhanced the effective quantum yield of PSII photochemistry (15%) and electron transport rate (19%) due to upregulation of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase. Exogenous EBR application promoted significant increases in biomass, and these results were explained by the benefits on nutrient contents and ionic homeostasis, demonstrated by increased Ca2+/Ni2+, Mg2+/Ni+ 2 and Mn2+/Ni2+ ratios.

scholarly journals Changes in Photo-Protective Energy Dissipation of Photosystem II in Response to Beneficial Bacteria Consortium in Durum Wheat under Drought and Salinity Stresses

2020 ◽  
Vol 10 (15) ◽  
pp. 5031 ◽  
Author(s):  
Mohammad Yaghoubi Khanghahi ◽  
Sabrina Strafella ◽  
Carmine Crecchio
Keyword(s):  
Chlorophyll Fluorescence ◽  
Energy Dissipation ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Durum Wheat ◽  
Photochemical Quenching ◽  
Plant Growth Promoting Bacteria ◽  
Psii Photochemistry ◽  
Non Photochemical Quenching

The present research aimed at evaluating the harmless dissipation of excess excitation energy by durum wheat (Triticum durum Desf.) leaves in response to the application of a bacterial consortium consisting of four plant growth-promoting bacteria (PGPB). Three pot experiments were carried out under non-stress, drought (at 40% field capacity), and salinity (150 mM NaCl) conditions. The results showed that drought and salinity affected photo-protective energy dissipation of photosystem II (PSII) increasing the rate of non-photochemical chlorophyll fluorescence quenching (NPQ (non-photochemical quenching) and qCN (complete non-photochemical quenching)), as well as decreasing the total quenching of chlorophyll fluorescence (qTQ), total quenching of variable chlorophyll fluorescence (qTV) and the ratio of the quantum yield of actual PSII photochemistry, in light-adapted state to the quantum yield of the constitutive non-regulatory NPQ (PQ rate). Our results also indicated that the PGPB inoculants can mitigate the adverse impacts of stresses on leaves, especially the saline one, in comparison with the non-fertilized (control) treatment, by increasing the fraction of light absorbed by the PSII antenna, PQ ratio, qTQ, and qTV. In the light of findings, our beneficial bacterial strains showed the potential in reducing reliance on traditional chemical fertilizers, in particular in saline soil, by improving the grain yield and regulating the amount of excitation energy.

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