Environmental stress - what can we learn from chlorophyll a fluorescence analysis in woody plants? A review

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 and human-modified environments. We discuss both the circumstances under which ChF can be successfully used to assess woody plant health and the ChF parameters that can be useful in field research. Finally, we summarise the advantages and limitations of the ChF method in research on trees, shrubs, and woody vines

Photosynthetic efficiency of perennial ryegrass (Lolium perenne L.) seedlings in response to Ni and Cd stress

Abstract 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 signal could indicate a restriction in electron flow from PSII to PSI. The correlation between photosynthetic efficiency parameters, such as Area, Fo, Fm, and Fv, and growth parameters, confirmed that some photosynthetic efficiency parameters can be used as indicators for early detection of heavy metal effects

Phosphorus-deficiency stress in cucumber (Cucumis sativus L.) plants: early detection based on chosen physiological parameters and statistical analyses

Enhancing plant productivity and mitigating the impact of environmental stressors require a thorough understanding of phytomonitoring and physiological features indicative of plant health. This study delves into the response of cucumber plants to phosphorus deficiency employing diverse tools to identify key indicators and unravel the underlying mechanisms. Under phosphorus deficiency, a rapid response in older leaves was observed through the analysis of chlorophyll and carotenoid content. Molecular-level changes in photosynthetic performance were found to be age-dependent, as revealed by multidimensional statistical methods, highlighting the interconnectedness of examined features with the experimental setup timing. This can assist in understanding the long-term fluctuations in traits linked to phosphorus deficiency, facilitating early detection of stress

Efficacy of <i>Sterculia diversifolia</i> Leaf Extracts: Volatile Compounds, Antioxidant and Anti-Inflammatory Activity, and Green Synthesis of Potential Antibacterial Silver Nanoparticles

Sterculia diversifolia, widely distributed in Jordan as an ornamental plant, is a synonoum for Brachychiton populneus. Phytochemical studies examining the volatile chemicals in Sterculia diversifolia leaves are limited, despite the rising demand for their numerous applications. Furthermore, it was only recently that a report described the friendly synthesis of silver nanoparticles (AgNPs) using aqueous extract derived from Brachychiton populneus leaves. Therefore, AgNPs were produced using either aqueous plant extracts (AgWPE) or ethanolic plant extracts (AgEPE), and Shimadzu GC-MS equipment was used to detect volatile compounds in the ethanolic leaf extracts. GC-MS profile of leaf ethanolic extracts of the Jordanian chemotypes of S. diversifolia revealed the existence of major components: (3β)-Lup-20(29)-en-3-ol acetate (30.97%) and 1-octadecyne (24.88). Other compounds are squalene (7.19%), germanicol (6.23), dl-α-tocopherol (5.24), heptacosane (4.41), phytol (3.54) and pentacosane (2.89). According to published studies, these reported chemicals have numerous uses, including as animal feed, vitamin precursors, possible eco-friendly herbicides, antioxidants, and anti-inflammatory agents. Aqueous extracts of S. diversifolia leaves had total phenolic of 5.33 mg GAE/g extract and flavonoid contents of 64.88 mg QE/g extract, respectively. The results indicated the contribution of phenolic and flavonoids to this plant’s anti-inflammatory and antioxidant properties. The reduction in AgNO3 to AgNPs using S. diversifolia leaf extracts was confirmed by the change in solution color from colorless to dark black. Further characterization was attempted by X-ray diffraction, Malvern zeta-sizer and scanning electron microscope. The efficacy of synthesized Ag nanoparticles using aqueous or ethanolic plant extract of S. diversifolia against the Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus showed appreciable activity at 25 µg/mL concentration compared to the source plant extracts