The efficiency of chlorophyll (Chl) fluorescence for forecasting plant response to environmental ... more The efficiency of chlorophyll (Chl) fluorescence for forecasting plant response to environmental pollution was examined in four wheat cultivars. The plants were irrigated with wastewater from Razi petrochemical complex. A forecasting model was designed based on the data of maximal quantum yield of photosystem II (Fv/Fm), efficiency of both photosystems (PIABS), and Chl contents of 60-d analysis. A comparison of the forecasting model results with the real data of Fv/Fm, PIABS, and Chl in response to wastewater suggested Fv/Fm as an accurate tool for stress forecasting. The high salt concentration in wastewater induced high accumulation of H2O2, lipid peroxidation, inhibition of photosynthesis, and reduction in contents of proteins and carbohydrates, which resulted in growth suppression of all cultivars. Taken together, the negative effect of environmental pollution on crop can be detected at an early stage of stress using Fv/Fm as a fast and accurate tool to prevent irrecoverable damage to plants.
Environmental and Experimental Botany, Jun 1, 2021
Abstract Microcystis is a genus of unicellular blue-green algae that is toxic and can be troubles... more Abstract Microcystis is a genus of unicellular blue-green algae that is toxic and can be troublesome in freshwater, especially where organic material is abundant. The aim of this work was to analyse photosystems photochemistry of Microcystis spp. colonies under salt stress by the use of comprehensive chlorophyll a fluorescence signals measurements (prompt, delayed and modulated 820 nm reflection- MR 820). The cyanobacteria samples were taken from a natural aquatic environment. Chlorophyll a fluorescence measurements were made on the aqueous suspension of these organisms. The following salt solutions were applied with 10 days intervals: 0.00 (control), 0.05, 0.10, 0.20, 0.40, 0.80, and 1.00 M. Data was collected three times (10, 20 and 30 days after treatment), prior to increasing the salt concentration in the solution. We found that the salt stress inhibited electron transfer from the reduced PQ pool to the photosystem I (PSI) reaction center (P700+) and the inhibition of reoxidation of the plastoquinone molecule tightly bound to photosystem II- PSII (QA-). An inhibition of quantum yields of photoinduced electron transport in PSII reaction center to QA together with a reduction of the fast phase of photoinduced kinetics of the MR signal was also noted under this stress. We recommend the combined analyses of the prompt and delayed chlorophyll fluorescence along with MR 820 to be used as a novel qualitative method for studying photosynthetic machinery reactions not only in higher plants, but also in cyanobacteria.
Silver nanoparticles (AgNPs) are used in several industries and their continuous release into env... more Silver nanoparticles (AgNPs) are used in several industries and their continuous release into environment can damage the ecosystem. Our study observed the impact of two concentrations of AgNPs (1 and 5 mM) on wheat seedlings. In this study, the treatment of AgNPs was found to have a significant impact on growth parameters, such as root and shoot length of wheat seedlings, in addition to that biochemical parameters, such as activity of catalase, glutathione, flavonoid, and chlorophyll concentrations, were also affected. AgNPs apparently suppressed the photosynthetic activity of the seedlings, with a clear destruction of photosystems at 5 mM concentration. The result also indicated an improper regulation of PSI electron transport, resulting in a damage to chloroplast structure, including photosystem itself. Our study presents a mechanism of the AgNPs action of on photosynthetic processes in plants.
Chlorophyll a fluorescence (ChF) signal analysis has become a widely used and rapid, non-invasive... more Chlorophyll a fluorescence (ChF) signal analysis has become a widely used and rapid, non-invasive technique to study the photosynthetic process under stress conditions. It monitors plant responses to various environmental factors affecting plants under experimental and field conditions. Thus, it enables extensive research in ecology and benefits forestry, agriculture, horticulture, and arboriculture. Woody plants, especially trees, as organisms with a considerable life span, have a different life strategy than herbaceous plants and show more complex responses to stress. The range of changes in photosynthetic efficiency of trees depends on their age, ontogeny, species-specific characteristics, and acclimation ability. This review compiles the results of the most commonly used ChF techniques at the foliar scale. We describe the results of experimental studies to identify stress factors that affect photosynthetic efficiency and analyse the experience of assessing tree vigour in natural...
Perennial ryegrass is a grass species used to establish lawns in urban areas where pollution is a... more Perennial ryegrass is a grass species used to establish lawns in urban areas where pollution is a major environmental problems. Cadmium (Cd) and nickel (Ni) contribute significantly to these pollutants and may cause photosynthetic limitation. The main objective of this work was to perform a comprehensive analysis of photosynthetic efficiency of perennial ryegrass seedlings under Cd and Ni stress. Some of the main indices of photosynthetic efficiency (prompt and delayed chlorophyll-a fluorescence signals and modulated reflectance at 820 nm) were compared with growth parameters. Two cultivars were tested: 'Niga' and 'Nira'. A decrease in photosystem (PS) II and PSI activity was observed. This was due to an increase in nonradiative dissipation of the PSII antenna, a decrease in PSII antenna size, or a decrease in the number of photosynthetic complexes with fully closed PSII RCs. Efficiency of electron transport was decreased. The effect on the modulated reflectance sign...
Modern Tools and Techniques to Understand Microbes, 2017
The symbiotic relationship between plant and microbes is one of the most important types of symbi... more The symbiotic relationship between plant and microbes is one of the most important types of symbiosis among different living forms. Such kind of association helps both the host and the symbiont. Generally, bacteria and fungi are found in association with a variety of plants. It is believed that more than 80 % of plants from different families available on the earth surface have a symbiotic association with arbuscular mycorrhizal fungi. In this context, it is very important to understand the host–microbe interaction, which will elucidate the exact mechanisms involved in the symbiosis.
It is already known that there are many factors responsible for the successful grafting process i... more It is already known that there are many factors responsible for the successful grafting process in plants, including light intensity. However, the influence of the spectrum of light-emitting diodes (LEDs) on this process has almost never been tested. During the pre-grafting process tomato seedlings grew for 30 days under 100 μmol m-2 s-1 of mixed LEDs (red 70%+ blue 30%). During the post-grafting period, seedlings grew for 20 days under the same light intensity but the lightening source was either red LED, mixed LEDs (red 70% + blue 30%), blue LED or white fluorescent lamps. This was done to determine which light source(s) could better improve seedling quality and increase grafting success. Our results showed that application of red and blue light mixture (R7:B3) caused significant increase in total leaf area, dry weight (total, shoot and root), total chlorophyll/carotenoid ratio, soluble protein and sugar content. Moreover, this light treatment maintained better photosynthetic perf...
Oukarroum (2020) Salt stress affects mineral nutrition in shoots and roots and chlorophyll a fluo... more Oukarroum (2020) Salt stress affects mineral nutrition in shoots and roots and chlorophyll a fluorescence of tomato plants grown in hydroponic culture,
In this study, the comparative effect of TeA, DCMU, bentazone, DBMIB and MV on prompt fluorescenc... more In this study, the comparative effect of TeA, DCMU, bentazone, DBMIB and MV on prompt fluorescence and the MR 820 signal was simultaneously analyzed to provide an insight into how to elucidate their precise influence on Ageratina adenophora photosystems. The herbicides that interrupt electron transport beyond Q A , such as TeA, DCMU and bentazone, mainly increased the J-step level of fluorescence rise kinetics as a result of accumulation of Q A − , but showed differences in detail. The IP phase disappeared in the presence of DCMU and bentazone with a significant increase in F O value. TeA treatment retained the IP phase with lowering F M. As an inhibitor of plastoquinone re-oxidation, DBMIB increased the I-step (IP phase almost unnoticable) without changing F O and F M values. MV blocking PSI electron transfer through intercepting electrons from the FeS clusters suppressed the IP phase by decreasing the P level. Considering the W IP kinetics, TeA and DBMIB also affected PSI activity. After DCMU and MV treatment, the major change in the MR 820 kinetics was the loss of the slow phase due to the complete prevention of electron movement from PSII to re-reduce PC + and P 700 +. TeA, bentazone and DBMIB clearly suppressed the MR 820 slow phase and decreased the re-reduction rate of PC + and P 700 + (V red), significantly. However, there were still parts of electrons being donated to PC + and P 700 + , showing a smaller slow phase and PC + and P 700 + re-reduction rate. Additionally, TeA and DBMIB also somewhat declined the fast phase and PC and P 700 oxidation rate (V ox). was presented based on Strasser (1978) (Fig. 1). In this model, both PSII and PSI capture solar energy by antenna pigments and produce excited Chl molecules (Chl*), called absorption (ABS). Part of the ABS can be trapped and channelled to the reaction center (TR). The trapped energy flows through several medium electron transport complexes and participates in reducing Q A to Q A − (ET), which will be finally oxidized by the accepter side of PSI. As a consequence, CO 2 fixation is promoted. Along with electrons transferring, energy which cannot be utilized, it dissipates as heat and fluorescence (Strasser and Strasser, 1995).
The effect of seven herbicides (U-46 Combi Fluid, Cruz, MR, Basagran Bromicide, Lumax, and Gramox... more The effect of seven herbicides (U-46 Combi Fluid, Cruz, MR, Basagran Bromicide, Lumax, and Gramoxone) on Xanthium strumarium plants was studied. Chlorophyll content and fluorescence, leaf temperature, and stomatal conductance were evaluated at 12 h, 36 h, 60 h, and 84 h after herbicides application. U46 Combi Fluid, Cruz, and MR did not have a significant effect on chlorophyll fluorescence induction curves as compared to the control treatment. However, Basagran, Bromicide, Lumax, and Gramoxone showed significant changes in the shape of polyphasic fluorescence transients (OJIP transients). Variations in chlorophyll content index, leaf temperature, and stomatal conductance parameters were dependent on the type of applied herbicide. Our study revealed that the specific impact of the applied herbicides on the photosynthetic efficiency of plants is related to their chemical groups and their mechanism of action.
In this work, we tried to identify some specific chlorophyll a fluorescence (ChlF) parameters, th... more In this work, we tried to identify some specific chlorophyll a fluorescence (ChlF) parameters, that could enable detection of iron deficiency (Fedef) in radish plants (Raphanus sativus L.), before any visual symptoms appear. Changes in ChlF kinetics, JIP-test parameters, and chlorophyll content revealed that iron deficiency negatively affected PSII activity mainly via disruption of light absorption in light-harvesting complexes and by decreasing the activity of the primary quinone acceptor of PSII (Q A). Iron deficiency was clearly reflected in the changes of some JIP-test parameters, such as time to reach maximal fluorescence (FM), Area, normalized total area under the OJIP curve, and number of QA redox turnovers until FM is reached. The visible symptoms of Fedef appeared after 7 d of stress application, while ChlF measurements allowed us to detect iron deficiency during 1-3 d. Our results suggest that analysis of ChlF signals has a high potential for early detection of iron deficiency in radish plants.
Heavy metals are the main pollutants in electroplating wastewater. Currently, mainly chemical met... more Heavy metals are the main pollutants in electroplating wastewater. Currently, mainly chemical methods, which generate huge amounts of toxic sludge, are used in industrial wastewater treatment. To achieve environmental sustainability, there is a need to introduce an eco-friendly treatment of such contaminated wastewater. The present study was carried out in order to: (i) examine the hypothesis that a mixture of clinoptilolite and Chlorella vulgaris would enhance the efficiency of the removal of heavy metals, (ii) evaluate the potential application of sediments containing C. vulgaris and clinoptilolite after N-NH 4 assimilation for heavy metal removal, (iii) assess the selectivity of C. vulgaris and clinoptilolite for heavy metal removal and (iv) verify if there was potential applicability of C. vulgaris and clinoptilolite as effective and eco-friendly biomaterial for developing the Fe(III), Zn(II) and Pb(II) removal procedure. The influence of Pb(II) on Fe(III) and Zn(II) uptake was also studied. The study was conducted in a multimetallic system. The results demonstrated that all the sorbents were sufficient to remove >97.5% of Fe(III) and Pb(II) and 75% of Zn(II) from the investigated wastewater. The maximum uptake of lead and iron (99.9%) was more efficient than the uptake of zinc (94.8%). The mixture of unicellular algae and zeolites enhanced the efficiency of the removal of heavy metals since ion-exchange resins, such as zeolites, have mono-functional sites, whereas the algal cell walls have multi-functional sites, thereby complementing each other.
In this review, using the network analysis, based on the bibliometric data, collected from Web of... more In this review, using the network analysis, based on the bibliometric data, collected from Web of Science Core Collection database, we followed the development of chlorophyll fluorescence research (CFR) during 1947-2018. We confirmed dramatic increase in diversity of CFR from late 90-ties and vigorous development of this discipline in the last ten years. They are parallel to an increase in number of research areas and institutions involved and were triggered by the accumulation of knowledge and methodological, technological, and communication advances, especially modern fluorimeters and fluorescence techniques. The network analysis of keywords and research areas confirmed CFR changed into modern, multidisciplinary, highly collaborative discipline, in which in spite of many 'core' disciplines as plant science, environmental sciences, agronomy/food science and technology, the promising, modern areas developed: biochemistry and molecular biology, remote sensing, and big data artificial intelligence method.
Limitation of fresh water for agriculture irrigation is a worldwide problem, especially in countr... more Limitation of fresh water for agriculture irrigation is a worldwide problem, especially in countries located in the arid region like Egypt. This work demonstrates the impact of treated wastewater on two mango cultivars, cv. "Keitt" and cv. "Ewais". Treated wastewater contains comparatively more contaminant than fresh water, therefore salicylic acid (SA) was added to the treated wastewater to study their combined impact on mango cultivars. Observation indicated that both cultivars positively responded to treated wastewater and/or SA in a similar manner regarding growth, yield and fruit quality parameters. Obtained data revealed that treated wastewater and/or SA promoted vegetative growth and exhibited inhibitory role on the occurrence of malformation and fruitlet abscission. Studied biochemical features related to lipid peroxidation and oxidative system were differently affected. Cultivar "Keitt" had higher activity of catalase, peroxidase, and superoxide dismutase. as compared to cv. "Ewais". In the resistant cv. "Keitt" the constitutive level of lipid peroxidation was lower, but the activity of enzymatic antioxidants and non-enzymatic antioxidants was higher than the susceptible cultivar "Ewais". Similarly, Nitrogen metabolism enzymes and photosynthetic performance were inherently higher in cv. "Keitt". The comparative analysis between the two mango cultivars, based on malformation percentage analysis, indicated that cv. "Keitt" can be categorized into the tolerant group (1-10%), whereas cv. "Ewais" into susceptible ones (20-40%). Our results suggested that cv. "Keitt" possess better protection mechanisms against oxidative damage as compared to the relatively susceptible cultivar "Ewais". It is based on maintaining higher inherited and increased activity of the antioxidant system. Our work underlines the relation between malformation tolerance and antioxidant defence system. In this work, we suggest the performance of antioxidant defence system as a potential biochemical indicator for screening mango genotypes for malformation behaviour.
Fusarium verticillioides is one of the most common phytopathogenic fungi affecting maize producti... more Fusarium verticillioides is one of the most common phytopathogenic fungi affecting maize production, worldwide. The early identification of F. verticillioides infection in maize could be helpful to prevent the spreading of the fungus. Therefore, this study represents the use of chlorophyll fluorescence parameters to identify F. verticillioides infection in maize. Chlorophyll a fluorescence of control and F. verticillioides infected plants showed a typical polyphasic OJIP transient curve in both MO17 and B73 lines. Infected plants from both maize lines showed a different pattern of OJIP transient curve when compared to the control plants, respectively. This indicated that F. verticillioides had an effect on the photosynthesis of infected maize plants. This study demonstrated the importance of parameters such as: the activity of the watersplitting complex on the donor side of PSII (F v /F 0), minimum fluorescence (F 0), maximum fluorescence (F m), and absorption flux per one active reaction center (ABS/RC) to identify F. verticillioides infection in maize.
Global warming is an important issue which is leading to considerable changes in biomes. Environm... more Global warming is an important issue which is leading to considerable changes in biomes. Environmental biologists are continuously assessing how global warming is going to impact the current population. Peatlands are one of the most important component of the terrestrial ecosystems which makes only 3% of them but contain around 40% of soil organic carbon. The composition of peatland vegetation impacts a range of ecosystem functions, therefore, with a change in composition, the behavior and structure of peatland plant communities are predicted to change. This work is focused on the response of Sphagnum peatland (in Poland), to the manipulated environmental conditions. The experimental design consisted of four treatments (control, warming, reduced precipitation, and a combination of warming & reduced precipitation), three replicates of each. Active warming with infrared heaters (˜1.0-1.4°C peat temperature increase) and an automatic curtain to reduce precipitation (˜30% reduction in the rain) was applied continuously since 2015. The warming and reduced precipitation caused a significant variation in the vegetation indices such as Normalized Difference Vegetation Index (NDVI), Photochemical Reflectance Index (PRI), Water Band Index (WBI), and Chlorophyll Green Index (CI green) between manipulated sites. The abundance of major plant species was recorded between manipulated sites. The prompt chlorophyll fluorescence measurement was performed in the peak of the vegetation season of August 2017 which had shown a significant variation in photosynthetic induction curve and different photosynthetic parameters from the same plant species in between the manipulated sites. The data clearly indicate that a short-term climate manipulation resulted in the change of plant abundance and its physiology, which varied for different plant species. Our study indicates that the different plant species respond differently to climate change. The study also proposes the significance of simple vegetation indices for peatland vegetation observation.
Haberlea rhodopensis is a chlorophyll-retaining resurrection plant, which can survive desiccation... more Haberlea rhodopensis is a chlorophyll-retaining resurrection plant, which can survive desiccation to air dry state under both low light and sunny environments. Maintaining the integrity of the membrane during dehydration of resurrection plants is extremely important. In the present study, the diffusion model was improved and used for a first time to evaluate the changes in ion leakage through different cellular compartments upon desiccation of H. rhodopensis and to clarify the reasons for significant increase of electrolyte leakage from dry leaves. The applied diffusion approach allowed us to distinguish the performance of plants subjected to dehydration and subsequent rehydration under different light intensities. Well-hydrated (control) shade plants had lower and slower electrolyte leakage compared to control sun plants as revealed by lower values of phase amplitudes, lower rate constants and ion concentration. In well-hydrated and moderately dehydrated plants (50% relative water ...
Improvement of drought stress of mango plants requires intensive researches that focuses on physi... more Improvement of drought stress of mango plants requires intensive researches that focuses on physiological processes. In three successive seasons (2014, 2015and 2016) field experiments with four different strains of mango were subjected to two water regimes. The growth and physiological parameters of possible relevance for drought stress tolerances in mango were investigated. Yield and its components were also evaluated. The data showed that all growth and physiological parameters were increased under K 2 SiO 3 (Si) supplement and were followed by the interaction treatment (Si treatment and its combination with drought stress) compared to that of controlled condition. Drought stress decreased the concentration of auxins (IAA), gibberellins (GA) and cytokinins (CK) in the three mango cultivars leaves, whereas, it increased the concentration of abscisic acid (ABA). On the contrary, IAA, GA, and CK (promoters) endogenous levels were improved by supplementing Si, in contrary ABA was decreased. Drought stress increased the activity of peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD) in the leaves of all mango cultivars grown during three experimental seasons. However, Si supplementation reduced the levels of all these antioxidative enzymes, especially the concentration of SOD when compared to that of control leaves. Fruit quality was improved in three successive seasons when Si was applied. Our results clearly show that the increment in drought tolerance was associated with an increase in antioxidative enzyme activity, allowing mango plants to cope better with drought stress. Si possesses an efficient system for scavenging reactive oxygen species, which protects plant against destructive oxidative reactions, thereby improving the ability of the mango trees to withstand environmental stress in arid regions.
Perennial ryegrass (Lolium perenne L.) is one of the more popular grass species in Europe. It is ... more Perennial ryegrass (Lolium perenne L.) is one of the more popular grass species in Europe. It is commonly used for starting lawns in urban areas, where plant growth is limited by many environmental conditions. The contamination of soils by salt is one of the major problems in urban green areas, as well as in natural areas. The basic aim of this study is to provide a detailed in vivo analysis of the changes in the delayed chlorophyll fluorescence and MR 820 signals (induced by salt stress) of two lawn varieties of perennial ryegrass, and to find out if there are correlations between these parameters and gas exchange. Two lawn varieties of Lolium perenne L. were used: Nira and Roadrunner. Salinization was performed at 8 weeks after sowing by adding NaCl in water solution (0, 0.15, and 0.30 M). There were 8
The book begins with a detailed description of the characteristics of the photosynthetic apparatu... more The book begins with a detailed description of the characteristics of the photosynthetic apparatus and the processes that take place there, to then present the general principles of fluorescence. After that, it gives a description of the characteristics of direct and modulated fluorescence and a presentation of the shared and distinctive parameters of these two techniques. Then a brief presentation is made of other innovative approaches to the analysis of fluorescence (Chlorophyll Fluorescence Imaging - CFI, P700 absorbance, delayed fluorescence) and the relative tools. An important part of the book comprises a description of the possible applications of fluorescence techniques for the analysis of various types of stress (aridity, strong light radiations, UV, high and low temperatures, salinity, weedkillers, pollution, etc.) and, consequently, their possible use in agriculture, forestry and to protect the environment.
The efficiency of chlorophyll (Chl) fluorescence for forecasting plant response to environmental ... more The efficiency of chlorophyll (Chl) fluorescence for forecasting plant response to environmental pollution was examined in four wheat cultivars. The plants were irrigated with wastewater from Razi petrochemical complex. A forecasting model was designed based on the data of maximal quantum yield of photosystem II (Fv/Fm), efficiency of both photosystems (PIABS), and Chl contents of 60-d analysis. A comparison of the forecasting model results with the real data of Fv/Fm, PIABS, and Chl in response to wastewater suggested Fv/Fm as an accurate tool for stress forecasting. The high salt concentration in wastewater induced high accumulation of H2O2, lipid peroxidation, inhibition of photosynthesis, and reduction in contents of proteins and carbohydrates, which resulted in growth suppression of all cultivars. Taken together, the negative effect of environmental pollution on crop can be detected at an early stage of stress using Fv/Fm as a fast and accurate tool to prevent irrecoverable damage to plants.
Environmental and Experimental Botany, Jun 1, 2021
Abstract Microcystis is a genus of unicellular blue-green algae that is toxic and can be troubles... more Abstract Microcystis is a genus of unicellular blue-green algae that is toxic and can be troublesome in freshwater, especially where organic material is abundant. The aim of this work was to analyse photosystems photochemistry of Microcystis spp. colonies under salt stress by the use of comprehensive chlorophyll a fluorescence signals measurements (prompt, delayed and modulated 820 nm reflection- MR 820). The cyanobacteria samples were taken from a natural aquatic environment. Chlorophyll a fluorescence measurements were made on the aqueous suspension of these organisms. The following salt solutions were applied with 10 days intervals: 0.00 (control), 0.05, 0.10, 0.20, 0.40, 0.80, and 1.00 M. Data was collected three times (10, 20 and 30 days after treatment), prior to increasing the salt concentration in the solution. We found that the salt stress inhibited electron transfer from the reduced PQ pool to the photosystem I (PSI) reaction center (P700+) and the inhibition of reoxidation of the plastoquinone molecule tightly bound to photosystem II- PSII (QA-). An inhibition of quantum yields of photoinduced electron transport in PSII reaction center to QA together with a reduction of the fast phase of photoinduced kinetics of the MR signal was also noted under this stress. We recommend the combined analyses of the prompt and delayed chlorophyll fluorescence along with MR 820 to be used as a novel qualitative method for studying photosynthetic machinery reactions not only in higher plants, but also in cyanobacteria.
Silver nanoparticles (AgNPs) are used in several industries and their continuous release into env... more Silver nanoparticles (AgNPs) are used in several industries and their continuous release into environment can damage the ecosystem. Our study observed the impact of two concentrations of AgNPs (1 and 5 mM) on wheat seedlings. In this study, the treatment of AgNPs was found to have a significant impact on growth parameters, such as root and shoot length of wheat seedlings, in addition to that biochemical parameters, such as activity of catalase, glutathione, flavonoid, and chlorophyll concentrations, were also affected. AgNPs apparently suppressed the photosynthetic activity of the seedlings, with a clear destruction of photosystems at 5 mM concentration. The result also indicated an improper regulation of PSI electron transport, resulting in a damage to chloroplast structure, including photosystem itself. Our study presents a mechanism of the AgNPs action of on photosynthetic processes in plants.
Chlorophyll a fluorescence (ChF) signal analysis has become a widely used and rapid, non-invasive... more Chlorophyll a fluorescence (ChF) signal analysis has become a widely used and rapid, non-invasive technique to study the photosynthetic process under stress conditions. It monitors plant responses to various environmental factors affecting plants under experimental and field conditions. Thus, it enables extensive research in ecology and benefits forestry, agriculture, horticulture, and arboriculture. Woody plants, especially trees, as organisms with a considerable life span, have a different life strategy than herbaceous plants and show more complex responses to stress. The range of changes in photosynthetic efficiency of trees depends on their age, ontogeny, species-specific characteristics, and acclimation ability. This review compiles the results of the most commonly used ChF techniques at the foliar scale. We describe the results of experimental studies to identify stress factors that affect photosynthetic efficiency and analyse the experience of assessing tree vigour in natural...
Perennial ryegrass is a grass species used to establish lawns in urban areas where pollution is a... more Perennial ryegrass is a grass species used to establish lawns in urban areas where pollution is a major environmental problems. Cadmium (Cd) and nickel (Ni) contribute significantly to these pollutants and may cause photosynthetic limitation. The main objective of this work was to perform a comprehensive analysis of photosynthetic efficiency of perennial ryegrass seedlings under Cd and Ni stress. Some of the main indices of photosynthetic efficiency (prompt and delayed chlorophyll-a fluorescence signals and modulated reflectance at 820 nm) were compared with growth parameters. Two cultivars were tested: 'Niga' and 'Nira'. A decrease in photosystem (PS) II and PSI activity was observed. This was due to an increase in nonradiative dissipation of the PSII antenna, a decrease in PSII antenna size, or a decrease in the number of photosynthetic complexes with fully closed PSII RCs. Efficiency of electron transport was decreased. The effect on the modulated reflectance sign...
Modern Tools and Techniques to Understand Microbes, 2017
The symbiotic relationship between plant and microbes is one of the most important types of symbi... more The symbiotic relationship between plant and microbes is one of the most important types of symbiosis among different living forms. Such kind of association helps both the host and the symbiont. Generally, bacteria and fungi are found in association with a variety of plants. It is believed that more than 80 % of plants from different families available on the earth surface have a symbiotic association with arbuscular mycorrhizal fungi. In this context, it is very important to understand the host–microbe interaction, which will elucidate the exact mechanisms involved in the symbiosis.
It is already known that there are many factors responsible for the successful grafting process i... more It is already known that there are many factors responsible for the successful grafting process in plants, including light intensity. However, the influence of the spectrum of light-emitting diodes (LEDs) on this process has almost never been tested. During the pre-grafting process tomato seedlings grew for 30 days under 100 μmol m-2 s-1 of mixed LEDs (red 70%+ blue 30%). During the post-grafting period, seedlings grew for 20 days under the same light intensity but the lightening source was either red LED, mixed LEDs (red 70% + blue 30%), blue LED or white fluorescent lamps. This was done to determine which light source(s) could better improve seedling quality and increase grafting success. Our results showed that application of red and blue light mixture (R7:B3) caused significant increase in total leaf area, dry weight (total, shoot and root), total chlorophyll/carotenoid ratio, soluble protein and sugar content. Moreover, this light treatment maintained better photosynthetic perf...
Oukarroum (2020) Salt stress affects mineral nutrition in shoots and roots and chlorophyll a fluo... more Oukarroum (2020) Salt stress affects mineral nutrition in shoots and roots and chlorophyll a fluorescence of tomato plants grown in hydroponic culture,
In this study, the comparative effect of TeA, DCMU, bentazone, DBMIB and MV on prompt fluorescenc... more In this study, the comparative effect of TeA, DCMU, bentazone, DBMIB and MV on prompt fluorescence and the MR 820 signal was simultaneously analyzed to provide an insight into how to elucidate their precise influence on Ageratina adenophora photosystems. The herbicides that interrupt electron transport beyond Q A , such as TeA, DCMU and bentazone, mainly increased the J-step level of fluorescence rise kinetics as a result of accumulation of Q A − , but showed differences in detail. The IP phase disappeared in the presence of DCMU and bentazone with a significant increase in F O value. TeA treatment retained the IP phase with lowering F M. As an inhibitor of plastoquinone re-oxidation, DBMIB increased the I-step (IP phase almost unnoticable) without changing F O and F M values. MV blocking PSI electron transfer through intercepting electrons from the FeS clusters suppressed the IP phase by decreasing the P level. Considering the W IP kinetics, TeA and DBMIB also affected PSI activity. After DCMU and MV treatment, the major change in the MR 820 kinetics was the loss of the slow phase due to the complete prevention of electron movement from PSII to re-reduce PC + and P 700 +. TeA, bentazone and DBMIB clearly suppressed the MR 820 slow phase and decreased the re-reduction rate of PC + and P 700 + (V red), significantly. However, there were still parts of electrons being donated to PC + and P 700 + , showing a smaller slow phase and PC + and P 700 + re-reduction rate. Additionally, TeA and DBMIB also somewhat declined the fast phase and PC and P 700 oxidation rate (V ox). was presented based on Strasser (1978) (Fig. 1). In this model, both PSII and PSI capture solar energy by antenna pigments and produce excited Chl molecules (Chl*), called absorption (ABS). Part of the ABS can be trapped and channelled to the reaction center (TR). The trapped energy flows through several medium electron transport complexes and participates in reducing Q A to Q A − (ET), which will be finally oxidized by the accepter side of PSI. As a consequence, CO 2 fixation is promoted. Along with electrons transferring, energy which cannot be utilized, it dissipates as heat and fluorescence (Strasser and Strasser, 1995).
The effect of seven herbicides (U-46 Combi Fluid, Cruz, MR, Basagran Bromicide, Lumax, and Gramox... more The effect of seven herbicides (U-46 Combi Fluid, Cruz, MR, Basagran Bromicide, Lumax, and Gramoxone) on Xanthium strumarium plants was studied. Chlorophyll content and fluorescence, leaf temperature, and stomatal conductance were evaluated at 12 h, 36 h, 60 h, and 84 h after herbicides application. U46 Combi Fluid, Cruz, and MR did not have a significant effect on chlorophyll fluorescence induction curves as compared to the control treatment. However, Basagran, Bromicide, Lumax, and Gramoxone showed significant changes in the shape of polyphasic fluorescence transients (OJIP transients). Variations in chlorophyll content index, leaf temperature, and stomatal conductance parameters were dependent on the type of applied herbicide. Our study revealed that the specific impact of the applied herbicides on the photosynthetic efficiency of plants is related to their chemical groups and their mechanism of action.
In this work, we tried to identify some specific chlorophyll a fluorescence (ChlF) parameters, th... more In this work, we tried to identify some specific chlorophyll a fluorescence (ChlF) parameters, that could enable detection of iron deficiency (Fedef) in radish plants (Raphanus sativus L.), before any visual symptoms appear. Changes in ChlF kinetics, JIP-test parameters, and chlorophyll content revealed that iron deficiency negatively affected PSII activity mainly via disruption of light absorption in light-harvesting complexes and by decreasing the activity of the primary quinone acceptor of PSII (Q A). Iron deficiency was clearly reflected in the changes of some JIP-test parameters, such as time to reach maximal fluorescence (FM), Area, normalized total area under the OJIP curve, and number of QA redox turnovers until FM is reached. The visible symptoms of Fedef appeared after 7 d of stress application, while ChlF measurements allowed us to detect iron deficiency during 1-3 d. Our results suggest that analysis of ChlF signals has a high potential for early detection of iron deficiency in radish plants.
Heavy metals are the main pollutants in electroplating wastewater. Currently, mainly chemical met... more Heavy metals are the main pollutants in electroplating wastewater. Currently, mainly chemical methods, which generate huge amounts of toxic sludge, are used in industrial wastewater treatment. To achieve environmental sustainability, there is a need to introduce an eco-friendly treatment of such contaminated wastewater. The present study was carried out in order to: (i) examine the hypothesis that a mixture of clinoptilolite and Chlorella vulgaris would enhance the efficiency of the removal of heavy metals, (ii) evaluate the potential application of sediments containing C. vulgaris and clinoptilolite after N-NH 4 assimilation for heavy metal removal, (iii) assess the selectivity of C. vulgaris and clinoptilolite for heavy metal removal and (iv) verify if there was potential applicability of C. vulgaris and clinoptilolite as effective and eco-friendly biomaterial for developing the Fe(III), Zn(II) and Pb(II) removal procedure. The influence of Pb(II) on Fe(III) and Zn(II) uptake was also studied. The study was conducted in a multimetallic system. The results demonstrated that all the sorbents were sufficient to remove >97.5% of Fe(III) and Pb(II) and 75% of Zn(II) from the investigated wastewater. The maximum uptake of lead and iron (99.9%) was more efficient than the uptake of zinc (94.8%). The mixture of unicellular algae and zeolites enhanced the efficiency of the removal of heavy metals since ion-exchange resins, such as zeolites, have mono-functional sites, whereas the algal cell walls have multi-functional sites, thereby complementing each other.
In this review, using the network analysis, based on the bibliometric data, collected from Web of... more In this review, using the network analysis, based on the bibliometric data, collected from Web of Science Core Collection database, we followed the development of chlorophyll fluorescence research (CFR) during 1947-2018. We confirmed dramatic increase in diversity of CFR from late 90-ties and vigorous development of this discipline in the last ten years. They are parallel to an increase in number of research areas and institutions involved and were triggered by the accumulation of knowledge and methodological, technological, and communication advances, especially modern fluorimeters and fluorescence techniques. The network analysis of keywords and research areas confirmed CFR changed into modern, multidisciplinary, highly collaborative discipline, in which in spite of many 'core' disciplines as plant science, environmental sciences, agronomy/food science and technology, the promising, modern areas developed: biochemistry and molecular biology, remote sensing, and big data artificial intelligence method.
Limitation of fresh water for agriculture irrigation is a worldwide problem, especially in countr... more Limitation of fresh water for agriculture irrigation is a worldwide problem, especially in countries located in the arid region like Egypt. This work demonstrates the impact of treated wastewater on two mango cultivars, cv. "Keitt" and cv. "Ewais". Treated wastewater contains comparatively more contaminant than fresh water, therefore salicylic acid (SA) was added to the treated wastewater to study their combined impact on mango cultivars. Observation indicated that both cultivars positively responded to treated wastewater and/or SA in a similar manner regarding growth, yield and fruit quality parameters. Obtained data revealed that treated wastewater and/or SA promoted vegetative growth and exhibited inhibitory role on the occurrence of malformation and fruitlet abscission. Studied biochemical features related to lipid peroxidation and oxidative system were differently affected. Cultivar "Keitt" had higher activity of catalase, peroxidase, and superoxide dismutase. as compared to cv. "Ewais". In the resistant cv. "Keitt" the constitutive level of lipid peroxidation was lower, but the activity of enzymatic antioxidants and non-enzymatic antioxidants was higher than the susceptible cultivar "Ewais". Similarly, Nitrogen metabolism enzymes and photosynthetic performance were inherently higher in cv. "Keitt". The comparative analysis between the two mango cultivars, based on malformation percentage analysis, indicated that cv. "Keitt" can be categorized into the tolerant group (1-10%), whereas cv. "Ewais" into susceptible ones (20-40%). Our results suggested that cv. "Keitt" possess better protection mechanisms against oxidative damage as compared to the relatively susceptible cultivar "Ewais". It is based on maintaining higher inherited and increased activity of the antioxidant system. Our work underlines the relation between malformation tolerance and antioxidant defence system. In this work, we suggest the performance of antioxidant defence system as a potential biochemical indicator for screening mango genotypes for malformation behaviour.
Fusarium verticillioides is one of the most common phytopathogenic fungi affecting maize producti... more Fusarium verticillioides is one of the most common phytopathogenic fungi affecting maize production, worldwide. The early identification of F. verticillioides infection in maize could be helpful to prevent the spreading of the fungus. Therefore, this study represents the use of chlorophyll fluorescence parameters to identify F. verticillioides infection in maize. Chlorophyll a fluorescence of control and F. verticillioides infected plants showed a typical polyphasic OJIP transient curve in both MO17 and B73 lines. Infected plants from both maize lines showed a different pattern of OJIP transient curve when compared to the control plants, respectively. This indicated that F. verticillioides had an effect on the photosynthesis of infected maize plants. This study demonstrated the importance of parameters such as: the activity of the watersplitting complex on the donor side of PSII (F v /F 0), minimum fluorescence (F 0), maximum fluorescence (F m), and absorption flux per one active reaction center (ABS/RC) to identify F. verticillioides infection in maize.
Global warming is an important issue which is leading to considerable changes in biomes. Environm... more Global warming is an important issue which is leading to considerable changes in biomes. Environmental biologists are continuously assessing how global warming is going to impact the current population. Peatlands are one of the most important component of the terrestrial ecosystems which makes only 3% of them but contain around 40% of soil organic carbon. The composition of peatland vegetation impacts a range of ecosystem functions, therefore, with a change in composition, the behavior and structure of peatland plant communities are predicted to change. This work is focused on the response of Sphagnum peatland (in Poland), to the manipulated environmental conditions. The experimental design consisted of four treatments (control, warming, reduced precipitation, and a combination of warming & reduced precipitation), three replicates of each. Active warming with infrared heaters (˜1.0-1.4°C peat temperature increase) and an automatic curtain to reduce precipitation (˜30% reduction in the rain) was applied continuously since 2015. The warming and reduced precipitation caused a significant variation in the vegetation indices such as Normalized Difference Vegetation Index (NDVI), Photochemical Reflectance Index (PRI), Water Band Index (WBI), and Chlorophyll Green Index (CI green) between manipulated sites. The abundance of major plant species was recorded between manipulated sites. The prompt chlorophyll fluorescence measurement was performed in the peak of the vegetation season of August 2017 which had shown a significant variation in photosynthetic induction curve and different photosynthetic parameters from the same plant species in between the manipulated sites. The data clearly indicate that a short-term climate manipulation resulted in the change of plant abundance and its physiology, which varied for different plant species. Our study indicates that the different plant species respond differently to climate change. The study also proposes the significance of simple vegetation indices for peatland vegetation observation.
Haberlea rhodopensis is a chlorophyll-retaining resurrection plant, which can survive desiccation... more Haberlea rhodopensis is a chlorophyll-retaining resurrection plant, which can survive desiccation to air dry state under both low light and sunny environments. Maintaining the integrity of the membrane during dehydration of resurrection plants is extremely important. In the present study, the diffusion model was improved and used for a first time to evaluate the changes in ion leakage through different cellular compartments upon desiccation of H. rhodopensis and to clarify the reasons for significant increase of electrolyte leakage from dry leaves. The applied diffusion approach allowed us to distinguish the performance of plants subjected to dehydration and subsequent rehydration under different light intensities. Well-hydrated (control) shade plants had lower and slower electrolyte leakage compared to control sun plants as revealed by lower values of phase amplitudes, lower rate constants and ion concentration. In well-hydrated and moderately dehydrated plants (50% relative water ...
Improvement of drought stress of mango plants requires intensive researches that focuses on physi... more Improvement of drought stress of mango plants requires intensive researches that focuses on physiological processes. In three successive seasons (2014, 2015and 2016) field experiments with four different strains of mango were subjected to two water regimes. The growth and physiological parameters of possible relevance for drought stress tolerances in mango were investigated. Yield and its components were also evaluated. The data showed that all growth and physiological parameters were increased under K 2 SiO 3 (Si) supplement and were followed by the interaction treatment (Si treatment and its combination with drought stress) compared to that of controlled condition. Drought stress decreased the concentration of auxins (IAA), gibberellins (GA) and cytokinins (CK) in the three mango cultivars leaves, whereas, it increased the concentration of abscisic acid (ABA). On the contrary, IAA, GA, and CK (promoters) endogenous levels were improved by supplementing Si, in contrary ABA was decreased. Drought stress increased the activity of peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD) in the leaves of all mango cultivars grown during three experimental seasons. However, Si supplementation reduced the levels of all these antioxidative enzymes, especially the concentration of SOD when compared to that of control leaves. Fruit quality was improved in three successive seasons when Si was applied. Our results clearly show that the increment in drought tolerance was associated with an increase in antioxidative enzyme activity, allowing mango plants to cope better with drought stress. Si possesses an efficient system for scavenging reactive oxygen species, which protects plant against destructive oxidative reactions, thereby improving the ability of the mango trees to withstand environmental stress in arid regions.
Perennial ryegrass (Lolium perenne L.) is one of the more popular grass species in Europe. It is ... more Perennial ryegrass (Lolium perenne L.) is one of the more popular grass species in Europe. It is commonly used for starting lawns in urban areas, where plant growth is limited by many environmental conditions. The contamination of soils by salt is one of the major problems in urban green areas, as well as in natural areas. The basic aim of this study is to provide a detailed in vivo analysis of the changes in the delayed chlorophyll fluorescence and MR 820 signals (induced by salt stress) of two lawn varieties of perennial ryegrass, and to find out if there are correlations between these parameters and gas exchange. Two lawn varieties of Lolium perenne L. were used: Nira and Roadrunner. Salinization was performed at 8 weeks after sowing by adding NaCl in water solution (0, 0.15, and 0.30 M). There were 8
The book begins with a detailed description of the characteristics of the photosynthetic apparatu... more The book begins with a detailed description of the characteristics of the photosynthetic apparatus and the processes that take place there, to then present the general principles of fluorescence. After that, it gives a description of the characteristics of direct and modulated fluorescence and a presentation of the shared and distinctive parameters of these two techniques. Then a brief presentation is made of other innovative approaches to the analysis of fluorescence (Chlorophyll Fluorescence Imaging - CFI, P700 absorbance, delayed fluorescence) and the relative tools. An important part of the book comprises a description of the possible applications of fluorescence techniques for the analysis of various types of stress (aridity, strong light radiations, UV, high and low temperatures, salinity, weedkillers, pollution, etc.) and, consequently, their possible use in agriculture, forestry and to protect the environment.
Uploads
Papers by Hazem Kalaji