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Understanding the dynamics of excited-state vibrational energy relaxation in photosynthetic pigments is crucial for elucidating the mechanisms underlying energy transfer processes in light-harvesting complexes. Utilizing advanced femtosecond broadband transient fluorescence (TF) spectroscopy, we explored the excited-state vibrational dynamics of Chlorophyll-a (Chl-a) both in solution and within the light-harvesting complex II (LHCII). We discovered a vibrational cooling (VC) process occurring over ∼6 ps in Chl-a in ethanol solution following Soret band excitation, marked by a notable ultrafast TF blueshift and spectral narrowing. This VC process, crucial for regulating the vibronic lifetimes, was further elucidated through the direct observation of the population dynamics of higher vibrational states within the Qy electronic state. Notably, Chl-a within LHCII demonstrated significantly faster VC dynamics, unfolding within a few hundred femtoseconds and aligning with the ultrafast energy transfer processes observed within the complex. Our findings shed light on the complex interaction between electronic and vibrational states in photosynthetic pigments, underscoring the pivotal role of vibrational dynamics in enabling efficient energy transfer within light-harvesting complexes. [ABSTRACT FROM AUTHOR]

Selenium (Se) is considered a beneficial element for plants. It plays a fundamental role in several physiological processes that influence their growth, development, and productivity. However, the influence of Se depends on both the concentration used and the method of application. It was hypothesized that low concentrations of Se stimulate plant growth and development, and foliar applications are more effective as a method of application. For that reason, the objective of the present investigation was to evaluate the effectiveness of 5, 10, 25, and 50 µM of Se applied radically and foliarly in bell pepper crop employed in a soilless cultivation system. The presence of Se by both application methods stimulated plant production, dry biomass accumulation, and photosynthetic pigment content, as well as leaf concentration of nitrogen (N) and potassium (K), except for calcium (Ca), and phosphorus (P) which were influenced by the application method and Se concentration factor, respectively. Fruit size was favored by the Se concentration factor while shelf life was favored by the application method. Se concentration in fruit dry matter varied as a function of Se concentration and application method, being more effective for human consumption by foliar application. This demonstrates the potential of Se as a beneficial element and reinforces the importance of proper management of both the concentration and method of Se application in agricultural crop production. [ABSTRACT FROM AUTHOR]

• RB LED promoted the number of shoots and leaves of in vitro Kaempferia parviflora plants, while red LED improved the length of the shoots,. • The production of photosynthetic pigments was increased under white, blue and RGB light,. • Red LED induced the accumulation of carbohydrates, while RB LED increased the production of proteins, with the highest antioxidant activity of Kaempferia parviflora observed under white LED. Black ginger (Kaempferia parviflora) is a popular plant in Thailand and Malaysia that is valued for its medicinal properties, especially its aphrodisiac qualities. Light-emitting diodes (LEDs) have successfully induced regeneration and various growth responses of black ginger plants in vitro. This study aims to investigate LED-induced photomorphogenesis of black ginger and to evaluate its physiology state. Shoot explants were grown in vitro under irradiation of white (400–750 nm), red (660 nm), blue (460 nm), RB (440 nm; 660 nm), and RGB (400 – 660 nm) to determine the vegetative responses of black ginger plants under the influence of light quality after six weeks. Biochemical analyses such as photosynthetic pigments, total carbohydrate content, protein estimation and free radical scavenging activity were also performed. The highest percentage of shoots was obtained at 96.67 % under blue light, but the maximum number of shoots and leaves were produced under RB LED with 3.21 ± 0.25 and 3.92 ± 0.28, respectively. The red light significantly promoted shoot length with an average length of 3.07 ± 0.21 cm. Rooting was spontaneously induced in all light treatments, with the highest number of roots recorded under RGB lighting at 11.80 ± 1.30. In general, RGB light significantly promoted the synthesis of photosynthetic pigments such as total chlorophyll content, carotenoids and porphyrins with 0.68 ± 0.02 µg/ml, 248.67 ± 3.38 µg/g and 3.94 ± 0.11 µg/g, respectively. The highest carbohydrate and protein contents were obtained with red and RB lights at 80.07 ± 9.15 mg/g and 309.33 ± 0.58 µg/ml, respectively. The control plants with white LED light showed the highest DPPH radical scavenging activity 94.34 ± 0.04%. Our results indicate that different light qualities induce photomorphogenesis of in vitro black ginger plants. The spectral combination with green light significantly improved the morphology and physiology of the plants. Therefore, the green spectrum should be considered as an important light source to promote plant growth in controlled environment agriculture. [ABSTRACT FROM AUTHOR]

Salicylic acid (SA) and melatonin (MEL) are affordable and effective phytohormones that help mitigate environmental stress. However, the combined benefits of SA and MEL in managing salt and drought stress in lettuce have not been evaluated. Therefore, this study was designed to evaluate the effectiveness of foliar spraying with 1.0 mM SA and 100 µM MEL, either alone or in combination, to enhance lettuce yield, growth, photosynthetic pigments, mineral status, quality, and antioxidant response under four different irrigation regimes. The irrigation practices used were: full irrigation (FI, irrigated with 0.18 dS m −1 at 100 % field capacity [FC]), deficit irrigation (DI, irrigated with 0.18 dS m −1 at 75 % FC), saline irrigation (SW, irrigated with 2.5 dS m −1 at 100 % FC), and deficit saline irrigation (DSW, irrigated with 2.5 dS m −1 at 75 % FC). Additionally, a control treatment (CK) was carried out with foliar application of distilled water and irrigation at 0.18 dS m −1. Compared to the CK, the application of SA, MEL, and SA+MEL increased evapotranspiration by 4.3 %, 8.6 %, and 15.1 %, and yield by 10.2 %, 16.4 %, and 23.8 %, respectively, under FI conditions. Furthermore, the joint application of SA and MEL at FI showed 25.3 % and 20.2 % higher K +/Na+ and Ca2+/Na+ ratios, respectively, compared to the CK. Additionally, the co-application of SA+MEL improved chlorophyll a, b, and carotenoid levels by 19.2 %, 17.2 %, and 20.4 %, respectively, under FI conditions, compared to the CK. Exogenous application of SA, MEL, and SA+MEL also improved total soluble solids by 17.3 %, 18.5 %, and 11.1 % and reduced nitrate content by 9.7 %, 10.4 %, and 13.5 % in lettuce under FI conditions, compared to the CK. The application of SA+MEL together resulted in a more pronounced increase in vitamin C content compared to supplying SA and MEL individually. Moreover, under DSW conditions, exogenous application of SA, MEL, and SA+MEL decreased the membrane stability index by 13.7 %, 9.4 %, and 6.3 %, increased malondialdehyde by 65.4 %, 40.8 %, and 36.6 %, and increased proline content by 68.4 %, 65.4 %, and 96.4 %, respectively, compared to the CK. Moreover, exogenous SA+MEL significantly increased the activities of superoxide dismutase, catalase, peroxidase enzymes under both SW and DSW conditions compared to the SA or MEL. Conversely, the activity of ascorbate peroxidase enzyme showed a gradual decrease in DI, SW, and DSW conditions, relative to the FI conditions. In conclusion, the integrated application of SA+MEL is an optimal strategy to enhance yield, morpho-physiological traits, nutrient homeostasis, antioxidant capacity, and quality in lettuce and mitigate the adverse effects of drought, salinity, and drought-salinity stress. [Display omitted] • Deficit saline irrigation has the most adverse effect on lettuce yield. • SA and MEL enhanced lettuce tolerance to drought and salinity stress. • Joint use of SA (1.0 mM) and MEL (100 µM) more effectively alleviates stress in lettuce. • SA+MEL improved the nutrient homeostasis and antioxidant capacity of lettuce. • SA+MEL combination increased vitamin C and decreased the nitrate content of lettuce. [ABSTRACT FROM AUTHOR]

Aluminum (Al) is known to inhibit plant growth and limit crop yields in acid areas. This study aimed to investigate the effect of endophytic fungus Glomerella sp. JP4 infection on the growth, photosynthetic pigments, antioxidant enzyme activities, organic acids contents, and Al content of endophyte-infected rice seedlings (EI) and endophyte-uninfected rice seedlings (EF) exposed to Al stress for 9 days. Al stress decreased shoot height, root length, and dry weight of EF plants. Endophyte infection increased the growth parameters except for root length. Compared to EF plants, the chlorophyll a+b content and carotenoid content were significantly enhanced in the EI plants. Antioxidant enzyme activity was also increased in the EI plants compared to the EF plants subjected to Al stress, while malondialdehyde (MDA) content was remarkably reduced. Endophytic infection significantly increased the contents of citrate and succinate in leaves, as well as that of lactate, malate, fumarate, and succinate in roots under Al stress. Endophyte infection decreased the Al content in the shoots and the roots and restricted the Al transfer from the roots to the shoots in the EI plants compared to the EF plants. Our results indicated that infection with endophytic fungus JP4 in the roots had an active role in promoting plant growth, alleviating the phytotoxic effects caused by Al exposure. [ABSTRACT FROM AUTHOR]

The generation of reactive oxygen/nitrogen species under either natural or stressful conditions activates antioxidant systems to balance the redox status in plant cells. The effect of seed priming with low concentrations of H2O2 and/or arginine (Arg) was examined on redox status of salinity-stressed Vicia faba in the present study. Salinity stress produced H2O2 and caused oxidative damage to photosynthetic pigments and membrane lipids represented by reduction in chlorophyll contents and carbohydrate production, and high accumulation of malondialdehyde, denoted as oxidative distress. Under saline conditions, Arg and/or H2O2 priming increased the activity of antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase), non-enzymatic antioxidants (phenols, flavonoids, anthocyanins and carotenoids), proline and total antioxidant activity (based on the FRAP method) followed by a reduction in the malondialdehyde content and an increase in the chlorophylls and water soluble carbohydrates contents. Altogether, the seed priming with H2O2 and Arg could constitute a 'priming memory' in seeds of V. faba, which recruited upon a subsequent salinity stress-exposure and induced stress-tolerance of primed beans trough invoking antioxidant systems. [ABSTRACT FROM AUTHOR]

Microalgae are the richest source of natural carotenoids—accessory photosynthetic pigments used as natural antioxidants, safe colorants, and nutraceuticals. Microalga Bracteacoccus aggregatus IPPAS C-2045 responds to stresses, including high light, with carotenogenesis—gross accumulation of secondary carotenoids (the carotenoids structurally and energetically uncoupled from photosynthesis). Precise mechanisms of cytoplasmic transport and subcellular distribution of the secondary carotenoids under stress are still unknown. Using multimodal imaging combining micro-Raman imaging (MRI), fluorescent lifetime (τ) imaging (FLIM), and transmission electron microscopy (TEM), we monitored ultrastructural and biochemical rearrangements of B. aggregatus cells during the stress-induced carotenogenesis. MRI revealed a decline in the diversity of molecular surrounding of the carotenoids in the cells compatible with the relocation of the bulk of the carotenoids in the cell from functionally and structurally heterogeneous photosynthetic apparatus to the more homogenous lipid matrix of the oleosomes. Two-photon FLIM highlighted the pigment transformation in the cell during the stress-induced carotenogenesis. The structures co-localized with the carotenoids with shorter τ (mainly chloroplast) shrunk, whereas the structures harboring secondary carotenoids with longer τ (mainly oleosomes) expanded. These changes were in line with the ultrastructural data (TEM). Fluorescence of B. aggregatus carotenoids, either in situ or in acetone extracts, possessed a surprisingly long lifetime. We hypothesize that the extension of τ of the carotenoids is due to their aggregation and/or association with lipids and proteins. The propagation of the carotenoids with prolonged τ is considered to be a manifestation of the secondary carotenogenesis suitable for its non-invasive monitoring with multimodal imaging. [ABSTRACT FROM AUTHOR]

Plants encounter many biotic entities, such as fungi, bacteria, and nematodes, which induce biotic stress that disrupts normal metabolism and limits the growth and productivity of plants. Currently, the use of plant growth-promoting bacterial endophytes instead of synthetic fungicides is intriguingly eco-friendly. An in vitro and in vivo antagonistic approach using Bacillus amyloliquefaciens RaSh1 was used to mimic the pathogenic effect of Alternaria alternata. The results showed that B. amyloliquefaciens significantly inhibited pathogenic fungal growth in vitro. Further, Capsicum annuum L. (pepper plants) were grown and subjected to inoculation with B. amyloliquefaciens and infected with A. alternata, and then the growth attributes, photosynthetic pigments, physio-biochemical parameters, and the level of endogenous phytohormones were assessed. Under the pathogen attack, the main responses, such as plant length, total fresh and dry weights, total chlorophylls, and pigments, were reduced, accompanied by increases in H2O2. As well, infection of pepper with A. alternata caused downregulation in the plant hormonal system by significantly decreasing gibberellins, indole-3-acetic acid, abscisic acid, as well as cytokinin concentrations. Although, with B. amyloliquefaciens application, an enhancement in growth, photosynthetic pigments, proline, thiol content, phenylalanine ammonia-lyase, and peroxidase in pepper plant leaves appeared while the content of H2O2 decreased. Endogenous phytohormones were found to be upregulated in B. amyloliquefaciens-inoculated and diseased plants. The current study found that B. amyloliquefaciens RaSh1 rescued pepper plant growth by modulating antioxidant defense and regulating hormones, and could be used to control A. alternata in an environmentally friendly manner while maintaining sustainable agriculture and food security. [ABSTRACT FROM AUTHOR]

Carnation (Dianthus caryophyllus L.) plant is native to the Mediterranean region. However, it is cultivated throughout the world for its beautiful flowers. In Pakistan, its flower yield and quality is very poor due to numerous abiotic stresses including salt stress, which drastically decreases plant growth, flower yield and quality. The aim of the present study was to evaluate foliar application of moringa and mint leaf extracts (0.03% each, separately) to mitigate negative effects of irrigation water salinity (0, 30 and 60 mM NaCl) on carnation plants. Salinity treatments reduced plant height, plant fresh and dry weights, leaf number, root length, number of flower buds, number of flowers, fresh and dry weights of flowers, photosynthetic pigments, i.e. chlorophyll a, chlorophyll b and total chlorophyll, and carotenoid content as well as ascorbic acid content. However, number of branches increased at 30 mM irrigation water salinity level and then decreased at 60 mM, while hydrogen peroxide (H2O2), malondialdehyde (MDA), peroxidase (POD) and catalase (CAT) activities increased with an increase in salinity level. Leaf length, root fresh weight, total phenolic content and superoxide dismutase (SOD) activity in leaves remained unaffected due to the salinity treatments. Over all, performance of mint leaf extract was better that of moringa; however, moringa leaf extract was more effective in improving leaf carotenoids content than mint leaf extract. Both, extracts reduced H2O2 and MDA contents. Leaf length, root length, root fresh weight, fresh weight of flowers and total phenolic content remained unaffected due to foliar application of extracts. Present study revealed that plant extracts especially mint leaf extract had good potential to mitigate negative effects of salt stress in carnation through regulation of metabolic and biochemical capabilities. [ABSTRACT FROM AUTHOR]

Drought stress, at different growth stages, causes substantial yield loss in major crops, thus, threatening global food security. Enhancement of drought stress tolerance in plants has been reported with the sole application of silicon (Si) and Zinc (Zn). However, the synergistic effects of their combined application and the exact mechanisms through which they enhance drought tolerance are still not fully understood. Therefore, the present study investigated the potential of Si and Zn to ameliorate drought stress in Eruca sativa (L.) and associated morphological and physio-biochemical mechanisms. The seeds were soaked in individual or combined Si (3 mM, from calcium silicate) and Zn (10 mM, from zinc sulfate) solutions for 8 h and 12 h. Water-primed and unprimed seeds were kept as control. Later, primed seeds were grown under various levels of drought viz. control (100% field capacity, FC) and 50% FC. Results revealed that drought stress significantly reduced growth traits, photosynthetic pigments, and reactive oxygen species and decreased antioxidative enzymes activities. Seed priming with Si and Zn increased seedling lengths, and their fresh and dry weights under drought stress with significantly higher values for the combined application of both. Moreover, Si and Zn-treated plants also showed a significant increase in chlorophyll pigments, i.e., chlorophyll and carotenoid contents in drought-exposed seedlings. Seed priming treatments improved drought-induced oxidative stress tolerance associated with higher activities of enzymatic and non-enzyme antioxidant activities and soluble sugar and proline contents. The results suggested that the combined application of Si and Zn serves as an appropriate treatment to increase the seedling growth, and physiological and biochemical attributes of E. sativa under drought stress conditions. [ABSTRACT FROM AUTHOR]

Terpenes serve important functions in enhancing plant thermotolerance. Cinnamomum camphora mainly has eucalyptol (EuL), camphor (CmR), linalool (LnL) and borneol (BeL) chemotypes basing on the uppermost monoterpenes. To reveal the thermotolerance mechanisms of these uppermost monoterpenes (eucalyptol, camphor, linalool, and borneol) in C. camphora, we surveyed the ROS metabolism and photosynthesis in the 4 chemotypes fumigated with the corresponding uppermost monoterpene after fosmidomycin (Fos) inhibiting monoterpene synthesis under high temperature at 38°C (Fos+38°C+monoterpene), and investigated the related gene expression in EuL and CmR. Meanwhile, the thermotolerance differences among the 4 uppermost monoterpenes were analyzed. In contrast to normal temperature (28°C), ROS levels and antioxidant enzyme activities in the 4 chemotypes increased under 38°C, and further increased in the treatment with Fos inhibiting monoterpene synthesis at 38°C (Fos+38°C), which may be caused by the alterations in expression of the genes related with nonenzymatic and enzymatic antioxidant formation according to the analyses in EuL and CmR. Compared with Fos+38°C treatment, Fos+38°C+monoterpene treatments lowered ROS levels and antioxidant enzyme activities for the increased non-enzymatic antioxidant gene expression and decreased enzymatic antioxidant gene expression, respectively. High temperature at 38° C reduced the chlorophyll and carotenoid content as well as photosynthetic abilities, which may result from the declined expression of the genes associated with photosynthetic pigment biosynthesis, light reaction, and carbon fixation. Fos+38°C treatment aggravated the reduction. In contrast to Fos+38°C treatment, Fos+38°C+monoterpene treatments increased photosynthetic pigment content and improved photosynthetic abilities by up-regulating related gene expression. Among the 4 uppermost monoterpenes, camphor showed strong abilities in lowering ROS and maintaining photosynthesis, while eucalyptol showed weak abilities. This was consistent with the recovery effects of the gene expression in the treatments with camphor and eucalyptol fumigation. Therefore, the uppermost monoterpenes can enhance C. camphora thermotolerance as signaling molecules, and may have differences in the signaling functions. [ABSTRACT FROM AUTHOR]

Background: Chromium (Cr) toxicity significantly threatens agricultural ecosystems worldwide, adversely affecting plant growth and development and reducing crop productivity. Trehalose, a non-reducing sugar has been identified as a mitigator of toxic effects induced by abiotic stressors such as drought, salinity, and heavy metals. The primary objective of this study was to investigate the influence of exogenously applied trehalose on maize plants exposed to Cr stress. Results: Two maize varieties, FH-1046 and FH-1453, were subjected to two different Cr concentrations (0.3 mM, and 0.5 mM). The results revealed significant variations in growth and biochemical parameters for both maize varieties under Cr-induced stress conditions as compared to the control group. Foliar application of trehalose at a concentration of 30 mM was administered to both maize varieties, leading to a noteworthy reduction in the detrimental effects of Cr stress. Notably, the Cr (0.5 mM) stress more adversely affected the shoot length more than 0.3mM of Cr stress. Cr stress (0.5 mM) significantly reduced the shoot length by 12.4% in FH-1046 and 24.5% in FH-1453 while Trehalose increased shoot length by 30.19% and 4.75% in FH-1046 and FH-1453 respectively. Cr stress significantly constrained growth and biochemical processes, whereas trehalose notably improved plant growth by reducing Cr uptake and minimizing oxidative stress caused by Cr. This reduction in oxidative stress was evidenced by decreased production of proline, SOD, POD, MDA, H2O2, catalase, and APX. Trehalose also enhanced photosynthetic activities under Cr stress, as indicated by increased values of chlorophyll a, b, and carotenoids. Furthermore, the ameliorative potential of trehalose was demonstrated by increased contents of proteins and carbohydrates and a decrease in Cr uptake. Conclusions: The study demonstrates that trehalose application substantially improved growth and enhanced photosynthetic activities in both maize varieties. Trehalose (30 mM) significantly increased the plant biomass, reduced ROS production and enhanced resilience to Cr stress even at 0.5 mM. [ABSTRACT FROM AUTHOR]

Chromium (Cr) toxicity hampers ornamental crops' growth and post-harvest quality, especially in cut flower plants. Nano-enabled approaches have been developing with phenomenal potential towards improving floricultural crop production under heavy metal-stressed conditions. The current pot experiment aims to explore the ameliorative impact of silicon nanoparticles (Si-NPs; 10 mM) and indole butyric acid (IBA; 20 mM) against Cr stress (0.8 mM) in Freesia refracta. The results showed that Cr stress significantly reduced morphological traits, decreased roots-stems biomass, abridged chlorophyll (14.7%) and carotenoid contents (27.2%), limited gas exchange attributes (intercellular CO2 concentration (Ci) 24.8%, stomatal conductance (gs) 19.3% and photosynthetic rate (A) 28.8%), condensed proline (39.2%) and total protein (40%) contents and reduced vase life (15.3%) of freesia plants by increasing oxidative stress. Contrarily, antioxidant enzyme activities, MDA and H2O2 levels, and Cr concentrations in plant parts were remarkably enhanced in Cr-stressed plants than in the control. However, foliar supplementation of Si-NPs + IBA (combined form) to Cr-stressed plants increased defense mechanism and tolerance as revealed by improved vegetative and reproductive traits, increased biomass, photosynthetic pigments (chlorophyll 30.3%, carotenoid 57.2%) and gaseous exchange attributes (Ci 33.3%, gs 25.6%, A 31.1%), proline (54.5%), total protein (55.1%), and vase life (34.9%) of metal contaminated plants. Similarly, the improvement in the activities of peroxidase, catalase, and superoxide dismutase was recorded by 30.8%, 52.4%, and 60.8%, respectively, compared with Crstressed plants. Meanwhile, MDA (54.3%), H2O2 (32.7%) contents, and Cr levels in roots (43.3), in stems (44%), in leaves (52.8%), and in flowers (78.5%), were remarkably reduced due to combine application of Si-NPs + IBA as compared with Cr-stressed nontreated freesia plants. Thus, the hypothesis that the synergistic application of Si-NPs + IBA will be an effective approach in ameliorating Cr stress is authenticated from the results of this experiment. Furthermore, the study will be significant since it will demonstrate how Si-NPs and IBA can work synergistically to combat Cr toxicity, and even when added separately, they can improve growth characteristics both under stressed and unstressed conditions. [ABSTRACT FROM AUTHOR]

Overuse of artificial chemical fertilizers could be detrimental to the environment. Utilizing beneficial microorganisms as biofertilizers is a sustainable technique that promotes soil health, crop yield, and ecosystem preservation. Curcuma longa L. is utilized as a medication since it has its antibacterial, anti-microbial, and anti-tumor characteristics, which reduce inflammation and hasten wound healing. The effect of E. cloacae strain MSR1, which is common in the roots of alfalfa grown in the Al-Ahsaa region, on C. longa plants is being investigated. C. longa rhizomes were planted under greenhouse conditions after being submerged in a solution of E. cloacae strain MSR1 (OD 500) or water treatment as a control for 12 hours. After 240 days of growing, ten randomly selected plants from each treatment were collected, and the vegetative growth and yield metrics were assessed. To investigate how E. cloacae influences C. longa production and chemical composition (photosynthetic pigment, nitrogen, phosphorus, potassium, and curcuminoid), measurements were conducted as well as genes diketide-CoA and curcumin synthases genes. Our research showed that C. longa's growth and yield were favorably impacted by E. cloacae. Significant increases in the related plants' chlorophyll a,b, carotenoid, nitrogen, phosphorus, and potassium levels were likewise a reflection of the enhanced effects shown in the growth and yield parameters. Treatment with E. cloacae raised the curcuminoid's three sub-components' compositions to varying degrees: bisdemethoxycurcumin, demethoxycurcumin, and curcumin. Comparing E. cloacae treated plants to the control, high expression levels of the genes diketide-CoA and curcumin synthase-1, -2, and 3 were also found. The treatment of E. cloacae is a good biostimulant candidate for boosting growth and yield as well as raising the medicinal qualities of C. longa, according to the overall results. [ABSTRACT FROM AUTHOR]

Trunk injection applies more nutrients in the correct volume and composition, delivering ideal results with fewer fertilizer treatments under drought-stress conditions. We used a completely randomized block design to examine the effects of trunk injection therapy on the development of drought stress tolerance in olive trees in arid climates. Treatments included seaweed extract (SWE), potassium amino acid chelate (PAC), calcium silicate (CS), and potassium silicate (PS) at five different concentrations: 0.25, 0.5, 1, 2, and 4% for each treatment. Each treatment consisted of four replications – four dry replications for each treatment and four irrigation controls – each receiving weekly irrigation. The findings showed that, in comparison to drought control, trunk injection of PAC at a concentration of 2% enhances the relative water content of leaf and proline and decreases electrolyte leakage (EL) and malondialdehyde (MDA) content. Chlorophyll a, carotenoids, and proline content are all significantly higher in the trunk after CS injection at a 4% concentration than in the control treatment. MDA and EL were also reduced. Injecting PS leads to an increase in proline and photosynthetic pigments. The SWE treatment improved the proline, relative leaf water content, and photosynthetic pigments. To sum up, trunk injection treatments under drought conditions improved plant photosynthetic pigments, increased proline content, prevented relative water content reduction, and prevented an increase in MDA and EL. In conclusion, among the several treatments, the use of 2% PS was the most effective at reducing the adverse effects of drought stress on olive plants. [ABSTRACT FROM AUTHOR]

The Coulomb coupling between transition densities of the pigments in photosynthetic pigment-protein complexes, termed excitonic coupling, is a key factor for the description of optical spectra and energy transfer. A challenging question is the quantification of the screening of the excitonic coupling by the optical polarizability of the environment. We use the equivalence between the sophisticated quantum chemical polarizable continuum (PCM) model and the simple electrostatic Poisson-TrEsp approach to analyze the distance and orientation dependence of the dielectric screening between chlorophylls in photosystem I trimers. On the basis of these calculations we find that the vacuum couplings V m n (0) and the couplings in the dielectric medium V m n = f m n V m n (0) are related by the empirical screening factor f m n = 0.60 + 39.6 θ (| κ m n | − 1.17) exp (− 0.56 R m n / Å) , where κ m n is the usual orientational factor of the dipole-dipole coupling between the pigments, R m n is the center-to-center distance, and the Heaviside-function θ (| κ m n | − 1.17) ensures that the exponential distance dependence only contributes for in-line type dipole geometries. We are confident that the present expression can be applied also to other pigment-protein complexes with chlorophyll or related pigments of similar shape. The variance between the Poisson-TrEsp and the approximate coupling values is found to decrease by a factor of 8 and 3–4 using the present expression, instead of an exponential distance dependent or constant screening factor, respectively, assumed previously in the literature. [ABSTRACT FROM AUTHOR]

Rising temperature is a major threat to the normal growth and development of maize, resulting in low yield production and quality. The mechanism of maize in response to heat stress remains uncertain. In this study, a maize mutant Zmhsl-1 (heat sensitive leaves) with wilting and curling leaves under high temperatures was identified from maize Zheng 58 (Z58) mutant lines generated by ethyl methanesulfonate (EMS) mutagenesis. The Zmhsl-1 plants were more sensitive to increased temperature than Z58 in the field during growth season. The Zmhsl-1 plants had lower plant height, lower yield, and lower content of photosynthetic pigments. A bulked segregant analysis coupled with whole-genome sequencing (BSA-seq) enabled the identification of the corresponding gene, named ZmHSL, which encodes an endo-β-1,4-xylanase from the GH10 family. The loss-of-function of ZmHSL resulted in reduced lignin content in Zmhsl-1 plants, leading to defects in water transport and more severe leaf wilting with the increase in temperature. RNA-seq analysis revealed that the differentially expressed genes identified between Z58 and Zmhsl-1 plants are mainly related to heat stress-responsive genes and unfolded protein response genes. All these data indicated that ZmHSL plays a key role in lignin synthesis, and its defective mutation causes changes in the cell wall structure and gene expression patterns, which impedes water transport and confers higher sensitivity to high-temperature stress. [ABSTRACT FROM AUTHOR]

Introduction: Salt stress is a major abiotic stress that affects crop growth and productivity. Choline Chloride (CC) has been shown to enhance salt tolerance in various crops, but the underlying molecularmechanisms in rice remain unclear. Methods: To investigate the regulatory mechanism of CC-mediated salt tolerance in rice, we conducted morpho-physiological, metabolomic, and transcriptomic analyses on two rice varieties (WSY, salt-tolerant, and HHZ, saltsensitive) treated with 500 mg·L-1 CC under 0.3% NaCl stress. Results: Our results showed that foliar application of CC improved morphophysiological parameters such as root traits, seedling height, seedling strength index, seedling fullness, leaf area, photosynthetic parameters, photosynthetic pigments, starch, and fructose content under salt stress, while decreasing soluble sugar, sucrose, and sucrose phosphate synthase levels. Transcriptomic analysis revealed that CC regulation combined with salt treatment induced changes in the expression of genes related to starch and sucrose metabolism, the citric acid cycle, carbon sequestration in photosynthetic organs, carbon metabolism, and photosynthetic antenna proteins in both rice varieties. Metabolomic analysis further supported these findings, indicating that photosynthesis, carbon metabolism, and carbon fixation pathways were crucial in CC-mediated salt tolerance. Discussion: The combined transcriptomic and metabolomic data suggest that CC treatment enhances rice salt tolerance by activating distinct transcriptional cascades and phytohormone signaling, alongwithmultiple antioxidants and uniquemetabolic pathways. These findings provide a basis for further understanding the mechanisms of metabolite synthesis and gene regulation induced by CC in rice in response to salt stress, and may inform strategies for improving crop resilience to salt stress. [ABSTRACT FROM AUTHOR]

Globally, heavy metals especially arsenic (As) toxicity in staple crops like wheat has posed serious threats to human health, necessitating conducting fresh studies to find out biologically viable As toxicity mitigation strategies. Therefore, this study aimed to investigate the impact of foliar-applied silicon nanoparticles (SiNPs) at the tillering stage on the activation of physiological and antioxidant regulation in wheat to induce tolerance against varying As toxicity levels. The trial comprised two promising wheat cultivars (Anaaj and Ghazi) and five SiNPs regimes including 0, 30, 60, 90, and 120 ppm doses against As toxicity levels of 0 and 25 ppm. The recorded findings depicted that SiNPs regimes significantly improved morphological characteristics such as root length, fresh and dry weight, as well as shoot length, and fresh and dry weight of wheat cultivars. Additionally, the levels of chlorophyll pigments, including chlorophyll a, chlorophyll b, and total chlorophyll contents, were significantly increased in SiNPs-treated plants, indicating improved photosynthetic activity. The enhanced antioxidant enzyme activities, such as ascorbate peroxidase (APX), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), played a vital role in combating oxidative stress induced by As toxicity. Moreover, SiNPs application resulted in a significant reduction in As concentration in both leaves and roots, highlighting the ability of SiNPs to regulate the uptake and accumulation of arsenic and mitigate its toxic effects. In conclusion, the foliar application of SiNPs during the tillering stage of wheat effectively activated physiological and antioxidant regulation, leading to enhanced tolerance against As toxicity. [ABSTRACT FROM AUTHOR]

Microalgal lipids are precursors to the production of biodiesel, as well as a source of valuable dietary components in the biotechnological industries. So, this study aimed to assess the effects of nutritional (nitrogen, and phosphorus) starvations and salinity stress (NaCl) on the biomass, lipid content, fatty acids profile, and predicted biodiesel properties of green microalga Monoraphidium braunii. The results showed that biomass, biomass productivity, and photosynthetic pigment contents (Chl. a, b, and carotenoids) of M. braunii were markedly decreased by nitrogen and phosphorus depletion and recorded the maximum values in cultures treated with full of N and P concentrations (control, 100%). These parameters were considerably increased at the low salinity level (up to 150 mM NaCl), while an increasing salinity level (up to 250 mM NaCl) reduces the biomass, its productivity, and pigment contents. Nutritional limitations and salt stress (NaCl) resulted in significantly enhanced accumulation of lipid and productivity of M. braunii, which represented more than twofold of the control. Furthermore, these conditions have enhanced the profile of fatty acid and biodiesel quality-related parameters. The current study exposed strategies to improve M. braunii lipid productivity for biodiesel production on a small scale in vitro in terms of fuel quality under low nutrients and salinity stress. [ABSTRACT FROM AUTHOR]

SUMMARY Photosynthetic organisms must cope with rapid fluctuations in light intensity. Nonphotochemical quenching (NPQ) enables the dissipation of excess light energy as heat under high light conditions, whereas its relaxation under low light maximizes photosynthetic productivity. We quantified variation in NPQ kinetics across a large sorghum (Sorghum bicolor) association panel in four environments, uncovering significant genetic control for NPQ. A genome‐wide association study (GWAS) confidently identified three unique regions in the sorghum genome associated with NPQ and suggestive associations in an additional 61 regions. We detected strong signals from the sorghum ortholog of Arabidopsis thaliana Suppressor Of Variegation 3 (SVR3) involved in plastid–nucleus signaling. By integrating GWAS results for NPQ across maize (Zea mays) and sorghum‐association panels, we identified a second gene, Non‐yellowing 1 (NYE1), originally studied by Gregor Mendel in pea (Pisum sativum) and involved in the degradation of photosynthetic pigments in light‐harvesting complexes. Analysis of nye1 insertion alleles in A. thaliana confirmed the effect of this gene on NPQ kinetics in eudicots. We extended our comparative genomics GWAS framework across the entire maize and sorghum genomes, identifying four additional loci involved in NPQ kinetics. These results provide a baseline for increasing the accuracy and speed of candidate gene identification for GWAS in species with high linkage disequilibrium. [ABSTRACT FROM AUTHOR]

AbstractFluoride is one of the most highly toxic soil and air pollutant prevalent in aquatic as well as terrestrial ecosystems. It seriously affects crop plant quality and productivity worldwide. Although a crop with great nutritional value; oats are susceptible to a variety of abiotic stresses. In the current study, the responses of six oat cultivars (JHO-99-1, JHO-2009, BJ-2012, KANT, JHO-822, and JHO-2000) to fluoride stress on growth measurements, photosynthetic pigments, and photosynthetic parameters have been studied. The fluoride (200 and 400 mg/kg) was added to the soil artificially, seeds were sown and the pots were kept under controlled conditions. Another set of plants without the fluoride treatment (0 mg/kg) were labeled as control. The experiment was conducted in a plant growth chamber and fluoride was artificially added to the soil prior to seeding. All six oat cultivars subjected to fluoride stress exhibited an overall decrease in plant growth when compared to the control. Further under fluoride stress, while the oat cultivars also showed a decrease in chlorophyll content and different photosynthetic parameters but on the contrary the antioxidant activities were increased. While the cultivar JHO-822 was most affected under fluoride stress, JHO-99-1 showed tolerance toward fluoride toxicity in comparison to other cultivars JHO-2009, BJ-2012, KANT, JHO-822, and JHO-2000. It is concluded that the tolerance or susceptibility of a cultivar to fluoride can be well correlated with various parameters studied in the present study. [ABSTRACT FROM AUTHOR]

The biogeochemical role of the sediments in the Guadalquivir River estuary, a vital region in the SW Iberian Peninsula, has been considerably neglected. The benthic microalgae (microphytobenthos, MPB) inhabiting the sediment surface could contribute to the autochthonous primary production and influence nutrient recycling in this hyper-turbid and hypernutrified estuary. Sediment-water column fluxes of O2 and dissolved inorganic nitrogen species (DIN = NH4 + +NO3 -+NO2 -) were assessed in laboratory incubations of sediment cores from Bonanza (mouth) and Lebrija (middle) during a 1-year study. Vertical profiles down to the 10-cm depth of photosynthetic pigments, organic C, total nitrogen, DIN, Fe2+, SO42-, and dissolved inorganic carbon (DIC) were also measured. Chlorophyll a in the sediment surface was higher at the estuarine mouth, exhibiting a seasonal pattern at both sites with highest values in winter and lowest in summer. Net community production (NCP) was higher in Bonanza compared with Lebrija and showed positive values most of the year, indicating that MPB contributed to the overall autochthonous primary production of the estuary. Seasonal changes in chlorophyll a and NCP were not parallel, suggesting different ecological controls. The sediment was generally a net sink of NO3 - and NH4 + in both sites, with several fold higher rates for NO3 - uptake. MPB N demand could account for the entire sediment DIN uptake in Bonanza and 21% in Lebrija. The remaining high NO3 - uptake rates indicate that they sustain elevated sediment denitrification rates. In contrast, rates of anaerobic oxidation of organic matter by Fe reduction and SO4 2-reduction, estimated from Fe2+ and SO4 2-vertical concentration profiles, were several orders of magnitude lower than the estimated water column-dependent denitrification rates. Overall, this study shows the importance of MPB in the Guadalquivir Estuary and the potential dominant role of denitrification in the anaerobic mineralization of organic matter. [ABSTRACT FROM AUTHOR]

The novelty of this study lies in demonstrating a new approach to control wilt diseases using Jania ethyl acetate extract. In the current investigation, the potential impacts of Jania sp. ethyl acetate extract (JE) on Tomato Fusarium oxysporum wilt (FOW) have been studied. The in vitro antifungal potential of JE against F. oxysporum (FO) was examined. GC–MS investigation of the JE revealed that, the compounds possessing fungicidal action were Phenol,2-methoxy-4-(2-propenyl)-,acetate, Eugenol, Caryophyllene oxide, Isoespintanol, Cadinene, Caryophylla-4(12),8(13)-dien-5à-ol and Copaen. Jania sp. ethyl acetate extract exhibited strong antifungal potential against FO, achieving a 20 mmzone of inhibition. In the experiment, two different methods were applied: soil irrigation (SI) and foliar application (FS) of JE. The results showed that both treatments reduced disease index present DIP by 20.83% and 33.33% respectively. The findings indicated that during FOW, proline, phenolics, and the antioxidant enzymes activity increased, while growth and photosynthetic pigments decreased. The morphological features, photosynthetic pigments, total phenol content, and antioxidant enzyme activity of infected plants improved when JE was applied through soil or foliar methods. It is interesting to note that the application of JE had a substantially less negative effect on the isozymes peroxidase and polyphenol oxidase in tomato plants, compared to FOW. These reactions differed depending on whether JE was applied foliarly or via the soil. Finally, the use of Jania sp. could be utilized commercially as an ecologically acceptable method to protect tomato plants against FOW. [ABSTRACT FROM AUTHOR]

Background: As a result of the world population and climate change impact increases (especially in arid environments), there is a critical need for high-yield, drought-tolerant wheat. Synthetic hexaploid wheat derived lines (SHW-DL), were created artificially by crossing different durum wheat cultivars (AABB) with accessions of Aegilops tauschii (DD), a beneficial source of new genes for common bread wheat (Triticum aestivum L). Here, we studied the response of a panel of 91 SHW-DL for drought tolerance based on physiological, antioxidant enzyme activities, and drought tolerance indices. Results: A wide range of variation and high values of heritability observed for grain yield, physiological and antioxidant traits indicating that the SHW-DL panel constitutes a valuable gene source for drought tolerance improvement of wheat. Despite decreases in grain yield (YLD), leaf area index (LAI), and relative water content (RWC) an increase in the content of malondialdehyde (MDA) was observed. Moreover, drought streass increased the antioxidant enzyme activities of ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD), and also photosynthetic pigments, proline (Pro), and MDA content. With higher values of grain yield, physiological and biochemical traits such as photosynthetic pigments, and RWC, and lower content of MDA, and peroxidase (H2O2) activity, SHW-DL performed better compared to common wheat lines under water stress conditions. Conclusions: Different responses to water stress within the germplasm and between synthetic and common wheat suggest that selection for adaptive and suitable genotypes is possible for drought tolerance in synthetic wheat germplasm. Genotypes 54, 98, 102, 105, 122, 124, 143, 159, 196, and 198 were identified to be directly used in breeding programs or indirectly by crossing them with other wheat germplasm collections. [ABSTRACT FROM AUTHOR]

Background: Abiotic stress, such as salinity, affects the photosynthetic apparatus of plants. It is reported that the use of selenium nanoparticles (Se NPs), and biochemical compounds such as chitosan (CS) increase the tolerance of plants to stress conditions. Therefore, this study aimed to elucidate the potential of Se NPs, CS, and their composite (CS + Se NPs) in improving the photosynthetic apparatus of C. sinensis under salt stress in greenhouse conditions. The grafted seedlings of C. sinensis cv. Valencia after adapting to the greenhouse condition, were imposed with 0, 50, and 100 mM NaCl. After two weeks, the plants were foliar sprayed with distilled water (control), CS (0.1% w/v), Se NPs (20 mg L− 1), and CS + Se NPs (10 and 20 mg L− 1). Three months after treatment, the levels of photosynthetic pigments, leaf gas exchange, and chlorophyll fluorescence in the treated plants were evaluated. Results: Under salinity stress, total chlorophyll, carotenoid, and SPAD values decreased by 31%, 48%, and 28% respectively, and Fv/Fm also decreased compared to the control, while the ratio of absorption flux (ABS), dissipated energy flux (DI0) and maximal trapping rate of PSII (TR0) to RC (a measure of PSII apparent antenna size) were increased. Under moderate (50 mM NaCl) and intense (100 mM NaCl) salinity stress, the application of CS + Se NPs significantly increased the levels of photosynthetic pigments and the Fv/Fm value compared to plants treated with distilled water. Conclusions: It may be inferred that foliar treatment with CS + Se NPs can sustain the photosynthetic ability of C. sinensis under salinity stress and minimize its deleterious effects on photosynthesis. [ABSTRACT FROM AUTHOR]

Promoting more floret primordia within a spike to acquire fertile potential during the differentiation and pre-dimorphism phases is critical for increasing the number of fertile florets per spike (NFFs). However, it is yet unknown the physiological mechanism regulating the complex and dynamic process. This study aimed to clarify how intra-spike hormones, pigments, and assimilates coordinate with each other to regulate spike morphology and then floret primordia development. A two-year field experiment was conducted with two winter wheat genotypes: N50 (big-spike with greater NFFs) and SM22 (mediumspike with fewer NFFs). We monitored high temporal and spatial-resolution changes in the number and morphology of floret primordia within a spike, as well as in intra-spike hormones, pigments, and assimilates. Our results revealed that the big-spike genotype had more NFFs than the medium-spike genotype, not only because they had more spikelets, but also because they had greater NFFs mainly at central spikelets. More floret primordia at central spikelets had sufficient time to develop and acquire fertile potential during the differentiation phase (167-176 d after sowing, DAS) and the pre-dimorphism phase (179 DAS) for the big-spike genotype than the medium-spike genotype. Floret primordia with fertile morphology during the pre-dimorphism phase always developed into fertile florets during the dimorphism phase. Those early-developed floret primordia most proximal and intermediate to the rachis in the big-spike genotype developed faster than the medium-spike genotype. Correspondingly, the spike dry matter and pigments (chlorophyll a, chlorophyll b, carotene, and carotenoids) content during 170-182 DAS, auxin (IAA) and cytokinin (CTK) content on 167 DAS were significantly higher in the big-spike genotype than in the medium-spike genotype, while jasmonic acid (JA) content was significantly lower in the big-spike genotype compared to the medium-spike genotype during 167-182 DAS. Since the significant differences in intra-spike hormone content of the two genotypes appear earlier than those in dry matter and pigments, we propose a possible model that helped the N50 genotype (big-spike) to form more fertile florets, taking the intra-spike hormone content as a signaling molecule induced assimilates and pigments synthesis, which accelerated the development of more floret primordia during the differentiation phase and then acquired fertile potential during the pre-dimorphism phase, finally improved the NFFs. Our high temporal and spatial-resolution analysis provides an accurate time window for precision cultivation and effective physiological breeding to improve the number of fertile florets in wheat. [ABSTRACT FROM AUTHOR]

The application of phyto-nanotechnology in horticulture is a sustainable tool for agriculture due to its cost-effectiveness and eco-friendly properties. Essential micro-elements have been used as nano-fertilizer to enhance crop production. Fine-tuning of the nanoparticle dose is also recognized as the critical factor determining their impact on plant growth. Therefore, this study aimed to investigate the effects of iron (Fe) and manganese (Mn) oxide nanoparticles (NPs) on potato plants physiological and biochemical changes under the hydroponic conditions. Observations revealed that the plant growing in the adapted hydroponics media (supplemented with 4.0 mg L− 1 Fe3O4 NPs and 1.0 mg L− 1 MnO2 NPs instead of original Fe and Mn salt respectively) improved various physiological and biochemical parameters, total biomass, and tuber yield compared to the untreated control. The growth-promoting impact of metal oxide NPs (hereafter refers as MONPs) simultaneously induced the activity of various antioxidant enzymes (SOD, CAT, POD) and contributed to the adequate reduction in malondialdehyde (MDA) and hydrogen peroxide (H2O2) content relative to the untreated control plants. This indicated that the application of MONPs could improve the potato yield per plant via modulating the plant antioxidant machinery. In addition, the application of MONPs as nano-nutrient appreciably improved the photosynthetic efficiency of plants via modulating the photosynthetic pigment content like Chl a, Chl b, total Chl, ratio Chl a/b, carotenoids as well as soluble sugar. The SEM-EDX elemental mapping also showed a slightly higher content of metals ions (Fe, Mn, and Ca) in the root and shoot tissues, however, the TEM analysis also confirmed absorption as well as transportation of MONPs in the root tissues growing in the presence of MONPs. This study opened the opportunity of utilizing MONPs as nano-nutrient in a hydroponic condition for development of pathogen-free potato tuber. [ABSTRACT FROM AUTHOR]

In Mediterranean regions, severe summers are becoming more common, leading to restrictions to vine productivity and yield quality, requiring sustainable practices to support this sector. We assessed the behaviour of three red grapevine varieties from the Douro Region to examine their tolerance to summer climate stress from the perspective that the less common varieties may have potential for increased use in a climate change scenario.Leaf and fruit biochemical profile, antioxidant activity and fruit colorimetric parameters were assessed at different phenological stages in Aragonez (AR), Tinto Cão (TC) and Touriga Nacional (TN) grape varieties.All three varieties exhibit significant variability in phenological timing, influenced by genetic and environmental factors. Photosynthetic pigment strategies differed among varieties. Chlorophyll content in AR was high to cope with high radiation, while TN displaying a balanced approach, and TC had lower pigment levels, with higher levels of phenolics, antioxidants, and soluble sugars, particularly during stress. The variations in berry biochemical profile highlight the distinct characteristics of the varieties. TC and TN show potential for coping with climate change, having elevated total acidity, while AR has larger and heavier berries with distinct coloration.These findings reinforce the need to study the behaviour of different varieties in each Terroir, to understand their diverse strategies to deal with summer climate stress. This will help in selecting the most suitable variety for these conditions under vineyard management in the Douro Region [ABSTRACT FROM AUTHOR]

Phaeocystis globosa is an important bloom‐forming marine phytoplankton species that often accumulates to large levels in temperate and tropical waters and has significant impacts on food webs and biogeochemical cycles. It can form "giant" colonies that reach 3 cm in diameter. Microscopic observations, colony elemental composition, and pigment composition were analyzed to assess the characteristics of colonies as a function of colony size. Particulate organic carbon (POC) per unit surface area, colonial cell density, and chlorophyll a per unit surface area all increased with colony size, in contrast to results from temperate waters. Cellular chl a averaged 0.85 pg chl · cell−1. Colonies had both photosynthetic and protective pigments, with fucoxanthin being the dominant accessory pigment. Based on chl a and pigment levels, it appears colonies were acclimated to relatively low irradiances, likely due to their life cycle and the extremely turbulent environment in which they grew. Mucous carbon ranged from 16.2% to 79.2% of the total POC, and mucous carbon per unit surface area increased with colony size, suggesting that the mucous envelope did not thin as the colony grew. Based on elemental composition, nitrogen did not appear to limit growth, but phosphorus:carbon ratios were similar to those of P‐limited cultures. Giant colonies represent an extreme response to the environment, but they do not appear to have greatly different characteristics than other tropical strains. [ABSTRACT FROM AUTHOR]

Simple Summary: Macroalgae in natural marine areas play an important role in mitigating ocean climate change. The complexity of natural conditions also makes it necessary to study macroalgae not only by considering the effects of changes in a single factor but also by exploring the coupled effects of different environmental conditions on macroalgae. Therefore, in this study, two species of macroalgae were used as experimental subjects to observe their growth processes under different co-treatments of temperature and CO2 concentration. The results of this study can provide a reference for how natural macroalgae can cope with future changes in ocean climate. To investigate the ecological impacts of macroalgae in the framework of shifting global CO2 concentrations, we conducted a study utilizing Ulva fasciata and Sargassum horneri specimens sourced from the Ma'an Archipelago in Zhejiang Province on how ocean acidification (OA) and temperature changes interact to affect the photosynthetic physiological responses of macroalgae. The results of the study showed that OA reduced the tolerance of U. fasciata to bright light at 20 °C, resulting in more pronounced photoinhibition, while 15 °C caused significant inhibition of U. fasciata, reducing its growth and photosynthetic activity, but OA alleviated the inhibition and promoted the growth of the alga to a certain extent. The tolerance of S. horneri to bright light was also reduced at 20 °C; the inhibition was relieved at 15 °C, and the OA further improved the algal growth. The Relative Growth Rate (RGR), photosynthetic pigment content, and the release of the dissolved organic carbon (DOC) of U. fasciata were mainly affected by the change in temperature; the growth of the alga and the synthesis of metabolites were more favored by 20 °C. A similar temperature dependence was observed for S. horneri, with faster growth and high metabolism at 15 °C. Our results suggest that OA reduces the tolerance of macroalgae to high light at suitable growth temperatures; however, at unsuitable growth temperatures, OA effectively mitigates this inhibitory effect and promotes algal growth. [ABSTRACT FROM AUTHOR]

The effect of dust pollution on the photosynthesis and respiration parameters of foliose lichens Hypogimnia physodes (L.) Nyl, Lobaria pulmonaria (L.) Hoffm. and Peltigera aphthosa (L.) Willd., collected near the bauxite mine (Komi Republic, Russia) was investigated. Microscopic analysis showed that fine dust particles were mainly on the thalli surface, with a few mineral inclusions in the thalli medulla. The deposition of dust particles caused significant changes in the optical properties of the lichen surface in the visible and infrared spectral regions. A number of spectral indices (BRI, REP, RES, WI) sensitive to lichen pollution by dust emissions from the bauxite mine were identified due changes in the reflectance spectra of the thalli. Shading of the algal layer by mineral particles deposited on the thalli surface did not affect the content of photosynthetic pigments and PS II photochemical activity parameters. At the same time, lichen CO2-exchange parameters were observed to change. Lichen thalli from the polluted area were characterized by lower values of net CO2 uptake in the moderate light conditions (150 µmol PAR/m2 s), and the proportion of dark respiration in the gas exchange was 1.5 to 2 times higher than the values for thalli from background site. A 2-fold decrease in cytochrome respiration capacity was observed in thalli from the affected area. In thalli of L. pulmonaria and P. aphthosa, the energetically inefficient alternative respiratory pathway capacity increased 1.5‑fold and in H. physodes the activity of residual respiration increased more than 3.5-fold. The results obtained allowed an assessment of the chronic dust pollution effects on the foliose lichens symbionts functioning. The data may be useful for environmental biomonitoring. [ABSTRACT FROM AUTHOR]

Salinity poses a serious challenge for stevia cultivation to meet growing demand. This study investigates protective supplements for stevia grown under saline conditions. Seedlings were subjected to titanium dioxide nanoparticles (0, 150, and 300 ppm), putrescine (0 and 1 mM), and salt (0, 75, and 150 mM) in a factorial design. Morphological traits (plant height, leaf dry and fresh weight), photosynthetic pigments (chlorophyll a, b, total), proline content, soluble and glycoside sugars (rebaudioside A and stevioside), and antioxidant enzyme activity (catalase and peroxidase) were measured. Higher salt concentrations (150 mM NaCl) reduced plant height, leaf dry and fresh weight, and chlorophyll but increased proline, soluble and glycoside sugars, and antioxidant enzyme activity. Foliar applications of putrescine (1 mM) and TiO2 nanoparticles (150 and 300 ppm) mitigated salt stress by improving growth and physiological properties. Simultaneous application of putrescine (1 mM) and TiO2 nanoparticles (300 ppm) was most effective at enhancing secondary metabolite production, important for the pharmaceutical industry. This study demonstrates protective roles of putrescine and TiO2 nanoparticles for stevia cultivation under saline conditions. [ABSTRACT FROM AUTHOR]

Drought, an important abiotic stress factor, has a profound effect on plant growth, especially in arid and semi-arid regions. This study investigated the interactive effects of drought stress [100, 75, 50 and 25% Field Capacity (FC)] and plant development stages (20, 40 and 60 days after flowering) on pepper species (Capsicum annuumL. and Capsicum chinense Jacq.). The results show that drought affects plant morphology and reduces photosynthetic pigments while increasing phytochemicals [total phenolics (TPh), total flavonoids (TFv) and total antioxidant activity (TAa)], malondialdehyde (MDA), protein, proline, and antioxidant enzymes [catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD)] (P ≤ 0.05). Throughout plant development, a decrease in photosynthetic pigments and phytochemicals was observed, accompanied by an increase in biochemical components and antioxidant enzymes. The photosynthetic pigments of C. annuum were less affected by drought. Extreme irrigation conditions (25 and 100% FC) caused significant phytochemical changes. With increasing drought stress severity, C. annuum showed significantly higher biophysical and enzymatic values compared to C. chinense. Different stress conditions resulted in significantly higher increases in SOD, POD and CAT levels in C. annuum compared to C. chinense at all growth stages, with average increases of 1.40-fold, 1.25-fold and 1.75-fold, respectively. In addition, antioxidant enzyme activities were significantly higher in C. annuum with increasing stress severity, helping to cope with oxidative stress. In conclusion, C. annuum shows more stable morphological, physiological and biochemical performances compared to C. chinense, establishing itself as a more drought-tolerant species. [ABSTRACT FROM AUTHOR]

• Biofabrication of silver nanoparticles (AgNPs) using leaves extract of date palm as capping and reduction agents and silver nitrate as substrate. • Characterization of biogenic AgNPs using several techniques. • Evaluate the impact of biofabricated AgNPs on the growth and development of strawberry under closed cultivation conditions; morphological, physiological, and biochemical parameters were investigated. • The achieved results demonstrated that the biofabricated silver nanoparticles have tangible effect on growth and development of strawberry under closed cultivation conditions. Silver nanoparticles (AgNPs) have extensively been used in industrial and medical fields due to their chemical and physical features such as quantum scale effects, size, surface, and interface effects. In addition, AgNPs are being used in the agricultural sector to enhance plant growth and development. However, most previous reports have focused on AgNPs phytotoxicity rather than positive impact on plant growth and development. Therefore, this research is aimed to investigate the effect of biofabricated AgNPs on biomass, physiological and biochemical indices of strawberry under closed cultivation conditions. Thus, AgNPs were fabricated biologically using plant extract, while the synthesis AgNPs was confirmed using several appropriate techniques such as UV–visible spectrophotometer (UV), Zeta potential analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscope (SEM), and energy dispersive X-ray (EDX). Thereafter, different concentrations (0, 20, 40 mg/L) of biofabricated AgNPs were supplemented to the nutrient medium of strawberry explants and incubated for 90 days. Next, biomass, physiological and biochemical indices were estimated. The obtained results revealed that AgNPs with an average size 100 nm, spherical shape and negative charge have an effective and tangible impact on the conditions. The addition of AgNPs to strawberry medium led to an increase in biomass, photosynthetic pigments, as well as total protein content and superoxidase dismutase (SOD) activity were upregulated. Total sugar content (TSC) and total phenolic content (TPC) were decreased under biofabricated AgNPs treatment compared to untreated explants. Moreover, the influence of biofabricated AgNPs on plant phytohormones such Indole-3-acetic acid (IAA) and Abscisic acid (ABA) were chromatographically investigated. The obtained results demonstrated that IAA content was increased behave to AgNPs, while ABA hormone decreased in treated plants comparing to the control. This study concluded that biofabricated AgNPs have played a vital role in the growth and development of strawberry as well as in combating the stress originating in closed cultivation rooms. [ABSTRACT FROM AUTHOR]

The positive effects of Trichoderma on the antioxidant responses of nodulated cowpea plants under aluminum (Al) stress are not well documented. This study aims to evaluate the effects of different microbial consortia of Bradyrhizobium yuanmingense (bradyrhizobia) and Trichoderma species (T. asperelloides T02, T. asperellum T77, or T. harzianum T78) on the growth and antioxidant responses of cowpea under Al stress. Coinoculation with Bradyrhizobia and Trichoderma resulted in greater growth (plant height and root length) and biomass (dry weight of shoots and roots) compared to single inoculations. The dual application of bradyrhizobia and T. asperellum T77 to Al-treated plants increased chlorophyll- a (36 %), chlorophyll- b (210 %), and carotenoid (92 %) contents. Under Al stress, plants inoculated with bradyrhizobia exhibited a 53 % increase in anthocyanin content compared to the unstressed control. The highest levels of reduced ascorbate and ascorbate redox state were observed in plants coinoculated with bradyrhizobia and Trichoderma , whereas oxidized ascorbate accumulated more in plants with single inoculations (bradyrhizobia or Trichoderma). Lipid peroxidation and hydrogen peroxide levels were 50 % lower in plants coinoculated with bradyrhizobia and Trichoderma. Additionally, these plants showed increased activities of superoxide dismutase, catalase, ascorbate peroxidase, and peroxidases under Al stress, particularly in those coinoculated with bradyrhizobia and T. asperelloides T02 and T. harzianum T78. Our results confirm that the presence of bradyrhizobia and Trichoderma in the cowpea rhizosphere mitigates oxidative damage caused by reactive oxygen species under Al stress and positively influences cowpea growth and development under stressful conditions. [Display omitted] • Growth and biomass were superior in cowpea coinoculated with bradyrhizobia and Trichoderma. • Dual application of bradyrhizobia and Trichoderma on Al-treated plants improved photosynthetic pigments. • Lipid peroxidation and hydrogen peroxide content were inferior in plants coinoculated with bradyrhizobia and Trichoderma under Al stress. • Antioxidant enzymes were improved in cowpea coinoculated with bradyrhizobia and Trichoderma under Al stress. [ABSTRACT FROM AUTHOR]

• Drought stress severely affects plant growth and development. • The use of glycine betaine encapsulated chitosan nanoparticles is an efficient strategy to alleviate drought stress. • Chitosan and glycine betaine encapsulated chitosan nanoparticles increased the physiological, morphological and molecular attributes of maize plant. • Glycine betaine encapsulated chitosan nanoparticles were more effective under drought stress as compared to alone nanoparticles. Drought is one of the main abiotic stresses that affect the growth and development of maize crop, thus causing food crises across the world. Nanoparticles are considered an effective tool for improving crop yield by upgrading the plant tolerance mechanism under abiotic stress. In this study, we investigated the role of foliar application of glycine betaine-encapsulated chitosan loaded nanoparticles (LNPs) and unloaded chitosan nanoparticles (NPs) in improving morphological, physiological, biochemical and molecular attributes in two maize varieties, HNG and CZP, grown under drought stress. Petri plates experiment was performed to screen different levels of drought (5 % and 20 %) and nanoparticle concentrations (10, 20 and 40 μg NPs). In the pot experiment, 20 % drought stress along with 20 μg LNPs and 20 μg NPs were used to examine the morphological, physiological and biochemical attributes of maize plants. Drought stress led to a significant reduction in fresh and dry weight, relative water content, root and shoot lengths, photosynthetic pigments, and antioxidant enzyme activities, including catalase, superoxide dismutase, ascorbate peroxidase, and proline content compared to control plants. However, foliar application of LNPs resulted in increased photosynthetic pigments, enhanced antioxidant enzyme activity, and elevated proline content under both control and drought-stressed conditions. Conversely, malondialdehyde (MDA) content decreased significantly with the application of LNPs and NPs alone under stress conditions. Moreover, nanoparticles also enhanced the relative expression levels of antioxidant genes, ZmAPX, ZmCAT , and ZmSOD. These findings highlight the potential of LNPs as an ecofriendly which helps in ameliorating drought stress in maize, and other plants. [ABSTRACT FROM AUTHOR]

• Neomarica longifolia is a commercially important ornamental iris plant. • Silicon nanoparticles (SiNPs) along with plant hormones in the medium improved the rate of shoot amplification. • Silicon NPs had a positive impact on the morpho-structural differentiation of leaves. • Silicon NPs also increased chlorophyll contents, rooting efficiency, and acclimatization of plantlets. Neomarica longifolia (Link & Otto) Sprague is a commercially important ornamental iris plant. This study aimed to explore in vitro regeneration and the relevance of silicon nanoparticles during the shoot amplification phase and their impact on the subsequent development of plants, structural differentiation, and rooting efficiency of N. longifolia. A maximum number of shoots (4.3 per explant) from node explants was recorded on Murashige and Skoog's (MS) medium augmented with 1.5 mg L−1 6-benzylaminopurine (BAP). However, lower concentration of BAP (0.5 mg L−1) combined with 0.2 mg L−1 Indole-3-acetic acid (IAA) were optimal for multiple shoot production (9.3 shoots). The foliages of such shoots were structurally weak and underdeveloped with reduced photopigments. The incorporation of 2.0 mg L−1 SiNPs in the nutrient solution showed a positive impact on the rate of amplification (15.0 shoots per explant) and well differentiation of mechanical and vascular tissues and photopigments. The increased concentrations of SiNPs (beyond optimum) decreased the above-studied parameters. The shootlets obtained from optimized concentrations of SiNPs along with optimum plant growth regulators (PGRs) rooted maximum (94.5 % response, 13.0 roots per shoot) on ½ MS medium + 0.5 mg L−1 Indole-3-butyric acid (IBA) and survived well in the greenhouse. We, therefore, hypothesize that the incorporation of optimal SiNPs (2.0 mg L−1) along with optimal PGRs at the shoot proliferation phase is important for upregulating the rate of shoot amplification, differentiation of foliar architecture, synthesis of photopigments, root development, and survival of the plantlets during hardening. Furthermore, the present study addressed the limitations of in vitro -induced morpho-structural disorders by introducing SiNPs in the medium. [ABSTRACT FROM AUTHOR]

Ethanol has been reported as a supplementary substrate for microalgae cultivation, however, information about its effect on the morphology, growth and desired metabolites accumulation of Chlorella sorokiniana is limited. To bridge this gap, the effects of exogenous ethanol on C. sorokiniana was screened by providing 0.00, 0.0025, 0.025, 0.1 and 1% (v/v) ethanol. Results showed ethanol caused multifaceted effects. 0.0025% and 0.025% ethanol caused a small increase in cell volume, growth and photosystem II (PSII) function. In contrast, cell volume conspicuously increased and was up to 2.5-fold (63.5 µm3) and 3.6-fold (91.3 µm3) higher in the 0.1% and 1% ethanol treatment groups, respectively, compared with the control (25.1 µm3). 1% ethanol conspicuously reduced chlorophyll concentration, inhibited growth, damaged the photosynthetic apparatus and decreased PSII electron transport. Carbohydrate and lipid accumulation increased in the 0.1% (112.6±7.8 µg mL-1) and 1% (217.87±31.6 µg mL-1) ethanol by 1.6 and 50-fold, compared to the control (70.5±2.2 µg mL-1and 7.2±2.6 µg mL-1). The cell permeability also increased coinciding with the pronounced increse of reactive oxygen species, particularly in the 0.1 and 1% ethanol treatment groups. There were giant palmloid-like cells containing unequal and numerous daughter cells in the higher ethanol treatments, indicating the cell cycle has been altered through suppression of mother cell cytokinesis, which could serve as a protective function to overcome ethanol stress. The results suggest that ethanol has the potential to be used as an impotent substrate to induce lipid and carbohydrate accumulation in C. sorokiniana cultivation. [ABSTRACT FROM AUTHOR]

Aims: Enhancing crop yields is a contemporary challenge of the modern world, and selenium (Se) has been shown to improve plant health against various abiotic stressors. This study aimed to evaluate the influence of Se on the biosynthesis of photosynthetic pigments, nitrogen metabolism, antioxidant metabolism, flavonoid synthesis and nodulation of cowpea plants. Methods: We carried out a soil experiment with five Se application rates (0, 7.5, 15, 30, and 45 µg kg−1) and a hydroponics experiment with four Se concentrations (0, 5, 10, and 15 µmol L−1). Results: Both experiments revealed hormetic-like responses of cowpea plants to Se, at both molecular and whole-plant levels. Se dose-dependently increased the synthesis of chlorophylls, carotenoids and pheophytin as well as the efficiency of enzymatic antioxidant metabolism by decreasing MDA levels and increasing CAT and APX activity. Selenium also enhanced nitrate reductase activity, resulting in greater biosynthesis of amino acids and proteins in the leaves. However, the dose responses were not identical in the two experiments. Hormetic-like biphasic responses were uniquely revealed for daidzein, genistein, and kaempferol in the hydroponics experiment. Selenium also enhanced the number of nodules in roots, which generated increases in the production of ureides and greater production of shoot dry weight in both experiments. Low rates of Se stimulated the translocation of allantoic acid from nodules to leaves. Conclusions: This study adds new insights regarding Se effect on antioxidant and nitrogen metabolism, photosynthetic pigments and nodulation, which can increase cowpea yield. [ABSTRACT FROM AUTHOR]

This work studied the micropropagation of fegra fig (F. palmata Forssk.) during which we experienced the incidence of shoot-tip necrosis (STN). STN was evident during the shoot elongation stage, which was regenerated on Murashige and Skoog (MS) medium supplemented with 2 mg/L 6-benzylaminopurine. To alleviate SNT, we conducted a series of experiments and supplemented the medium with calcium chloride (40, 80, and 120 mg/L), ascorbic acid (50, 100, and 150 mg/L), silver nitrate (1, 2, and 3 mg/L), and boric acid (9.3, 12.4, and 15.5 mg/L). Results showed that all the treatments controlled STN at varying levels, and supplementation of medium with 3 mg/L silver nitrate reduced the incidence of STN from 80% to 24%. The regenerated shoots were rooted on the same medium with incubation of cultures in the dark for 3 weeks and subsequent 4 weeks of incubation under 16/8-hour light/dark photoperiod. The growth parameters (number of shoots and roots, length of the main shoot and root, fresh and dry weights), photosynthetic pigments (chlorophylls and carotenoids), and relative water content of plantlets were restored with the application of 3 mg/L silver nitrate to the medium. Incubation of cultures initially in the dark followed by 16/8-hour light incubation facilitated axillary shoot elongation. On the basis of our findings, it is recommended to culture the regenerated axillary shoots of fegra fig onto MS medium containing 3% sucrose, 1.5 mg/L activated charcoal, and 3 mg/L silver nitrate to manage STN effectively. [ABSTRACT FROM AUTHOR]

BACKGROUND: In recent decades cyanobacterial species have attracted research attention as potential sources of new biostimulants. In this study, the biostimulant effects of five cyanobacterial suspensions on the growth and essential oil composition of Thymus vulgaris L. were evaluated. The expression of key genes involved in the biosynthesis of thymol and carvacrol, such as DXR and TPS2, were investigated. RESULTS: A pot culture experiment revealed that cyanobacterial application significantly improved T. vulgaris L. growth indices, including plant height, dry and fresh weight, leaf and flower number, leaf area, and photosynthetic pigment content. Total phenol and flavonoid content in inoculated plants also showed a significant increase compared with the control. Anabaena torulosa ISB213 inoculation significantly increased root and shoot biomass by about 65.38% and 92.98% compared with the control, respectively. Nostoc calcicola ISB215 inoculation resulted in the highest amount of essential oil accumulation (18.08 ± 0.62) in T. vulgaris leaves, by about 72.19% compared with the control (10.5 ± 0.50%). Interestingly, the amount of limonene in the Nostoc ellipsosporum ISB217 treatment (1.67%) increased significantly compared with the control and other treatments. The highest expression rates of DXR and TPS2 genes were observed in the treatment of N. ellipsosporum ISB217, with 5.92‐fold and 5.22‐fold increases over the control, respectively. CONCLUSION: This research revealed the potential of the cyanobacteria that were studied as promising biostimulants to increase the production of biomass and secondary metabolites of T. vulgaris L., which could be a suitable alternative to chemical fertilizers. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Diabetes poses a significant global health burden, demanding safe and effective therapeutic interventions. Medicinal plants offer promising avenues for natural diabetic management. Galega officinalis (goat's rue) has long been recognized for its hypoglycemic potential, but optimizing its phytochemical content and antidiabetic activity remains a key challenge. This study aimed to address this aspect by investigating the impact of foliar application of chitosan and salicylic acid on the physiological and phytochemical properties of G. officinalis, and subsequently evaluating its antidiabetic efficacy compared to that of the established drug metformin. A randomized complete block design with three replications was employed. Laboratory mice were divided into treatment groups receiving G. officinalis extract from plants sprayed with four salicylic acid concentrations (0.5–3 mM/L) and four chitosan concentrations (0–0.8 g/L). Blood glucose levels and various physiological parameters were assessed. Chitosan at 0.4 g/L and salicylic acid at 2 mM significantly enhanced the growth, photosynthetic pigments, and antioxidant activity of G. officinalis. Notably, the extract from plants treated with 3 mM salicylic acid exhibited the highest total alkaloid content, a potential contributor to antidiabetic activity. In a separate study, diabetic mice treated with this optimized G. officinalis extract (50 mg/kg) exhibited significantly greater blood glucose reductions compared to those treated with metformin (500 mg). This study demonstrates the potential of chitosan and salicylic acid in optimizing the beneficial properties of G. officinalis. The extract derived from plants treated with 3 mM salicylic acid displayed superior blood glucose‐lowering efficacy compared to metformin, suggesting its promising role as a potential natural antidiabetic therapy. Further research is warranted to elucidate the specific bioactive compounds responsible for this enhanced activity and translate these findings into clinical applications. [ABSTRACT FROM AUTHOR]

Present study attempts to study the impact of Serlui-B hydroelectric dam on water quality ('water-energy nexus') of a Himalayan river and to devise possible phytotechnology for heavy metals remediation. Physico-chemical characteristics of water were analyzed using 'American Public Health Association (APHA)' methods while Atomic Absorption Spectrophotometer (AAS) was used for estimation of heavy metals. To this end, concentrations of Fe and Ni were recorded above permissible limit which can impose public health risks. Therefore, phytoremediation experiments were performed by using Pistia stratiotes L. (water lettuce) and effects of Fe and Ni concentrations (1.0, 2.0, and 5.0 mg/L) on photosynthetic pigments were observed. Phytoremediation investigations using 24 aquaria (of 40.5 L) revealed that P. stratiotes was an effective hyperaccumulator of Fe and Ni with maximum removal efficiency of 96.2% and 92%, respectively. In relation to bioaccumulation indices, the bioconcentration factor (BCF) values decreased with increase in Fe and Ni concentrations, whereas the translocation factor (TF) was noted higher at low concentrations and vice versa. Furthermore, the total chlorophyll content and carotenoid levels in P. stratiotes demonstrated negative significant correlation with the rise in Fe/Ni concentrations that may be considered as an adaptive biochemical strategy to mitigate metals induced oxidative stress. The present study can further be extrapolated to field phytoremediation for ameliorating both physico-chemical and metallic contaminants. Last, the role of microbial biodiversity associated with P. stratiotes should be elucidated in future to help achieve SDG 6 and environmental sustainability. [ABSTRACT FROM AUTHOR]

Sandy sediments of lowland streams are typically transported at low flow in the form of migrating ripples. In these bedforms, microbial communities spanning all trophic guilds (heterotrophic bacteria, fungi, photoautotrophic and phagotrophic protists) are exposed to highly frequent moving–resting cycles of sediment grains. Up to date, it is unknown to what extent ripple migration impacts community metabolism and composition as well as the vertical zonation of sediment‐associated multitrophic microbial communities compared to stationary sediments. We hypothesize that, as a result of mechanical abrasion and limited light supply, migrating ripple sediments have lower microbial abundance, diversity, metabolism and resource acquisition and no vertical zonation compared to stationary sediments. We collected samples from five lowland streams in north‐eastern Germany between May and June 2020. The coarser and better sorted sediments of migrating ripples had a higher oxygen concentration and less organic matter than stationary sediments. Photosynthetic pigments, potential extracellular enzyme activities, bacterial cell counts, and fungal gene copies were lower in migrating ripples than in stationary sediments. In contrast, cell‐specific bacterial production was higher in migrating ripples. Metabarcoding revealed that bedform migration was important in shaping the community structure of bacteria, fungi, and phagotrophic protists. Dry mass‐related net community production, respiration, and bacterial production were higher in superficial compared to underlying layers irrespective of sediment transport. By modulating the abundance, diversity, and structure of different trophic guilds of microbial communities and their resource acquisition, migrating bedforms create streambed heterogeneity, shaping regional biodiversity and the flow of matter through the benthic food web. [ABSTRACT FROM AUTHOR]

The effect of copper at concentrations of 10, 20, and 50 μg/L on population growth, chlorophyll a fluorescence, and content of photosynthetic pigments (chlorophyll a and carotenoids) of the diatom Thalassiosira nordenskioeldii was studied. It was shown that at metal concentrations of 10 and 20 μg/L, the cell number started to increase from the first days of the experiment and, by the end of the experiment, exceeded that in the control group by 5.8- and 5.6 times, respectively. The intensity of chlorophyll a fluorescence and the content of photosynthetic pigments under these conditions were higher than in the control throughout the experiment. At a metal concentration of 50 μg/L, the growth of the cell population was inhibited at the beginning of the experiment; by the end of the experiment, the cell number exceeded that in control. The same pattern was recorded for the other parameters too. Based on the obtained data, it is hypothesized that copper at the studied concentrations may contribute to the proliferation of T. nordenskioeldii in the natural environment. [ABSTRACT FROM AUTHOR]

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Hydrogels have shown promise in improving soil quality and alleviating plant drought stress. This study investigated the effectiveness of four hydrogel composites composed of polyvinyl alcohol, sodium alginate, and pine or olive tree biochar in improving bean (Phaseolus vulgaris) plant growth and soil microbial activities. The experiment was conducted in natural soil, where biochar–hydrogel composites were applied at a concentration of 0.75% hydrogel per soil weight (w/w) for 35 days under two different moisture conditions: adequate moisture (70% of water holding capacity (WHC)) and drought stress (40% WHC). The results showed variation between hydrogel composites and, more importantly, between water regimes. Under water deficit conditions, biochar–hydrogel composites consistently caused a decrease in plant weight and in chlorophyll (CHL) CHLa/CHLb ratio. Furthermore, antioxidant enzyme activities and malondialdehyde and protein levels generally increased in contrast to the observations at 70% WHC. Regarding microbial activities, the composites reduced soil respiration (12–38%) while promoting phosphatase activity (42–65%) under both moisture regimes. Overall, the introduction of hydrogel composites did not show consistently positive effects on either plants or soil microorganisms. To thoroughly evaluate the efficacy of these hydrogels as soil amendments, further studies are needed, considering different soil types, plant species, and hydrogel application rates. [ABSTRACT FROM AUTHOR]

Featured Application: The findings from this research may have a specific and so far unique application in creating new packaged food products that are not traditionally distributed as such. The results show that the selection of proper packaging material with good thickness, transparency and permeability characteristics along with favorable storage conditions can help to preserve the antioxidant compounds of fresh-cut nettle leaves for 14 days. Green leafy vegetables are very challenging in terms of storage and preservation, while packaging in controlled conditions with the selection of appropriate polymer material is crucial for maintaining their nutritional value and quality. Various packaging materials have different gas and water vapor permeability as well as physicochemical properties that can create a specific environment inside the package, therefore affecting the chemical composition, sensory characteristics, and overall quality of packed leafy vegetables. Stinging nettle is an edible plant with a high antioxidant content, making it a valuable leafy vegetable. Therefore, this study aimed to evaluate the influence of four packaging materials (biaxially oriented polypropylene (BOPP), low-density polyethylene (LDPE), polyamide/polyethylene (PA/PE), and polylactic acid (PLA)) on the antioxidant content of packed fresh nettle leaves during 14-day storage. Ascorbic acid content was the highest after 6 days of storage, equally well preserved in all tested films, with an average of 86.74 mg/100 g fm (fresh mass). After 14 days of storage, the total phenolic content was best preserved when packed in LDPE. The content of caffeoylmalic and chlorogenic acids was the highest in LDPE after 6 days. In addition, leaves packed in LDPE after 6 days of storage had the highest content of all photosynthetic pigments. According to FRAP analysis, the antioxidant capacity was best maintained in LDPE (at the 14th day, the measured capacity was 43.61 µmol TE/g). This study shows that the type of packaging material (BOPP, LDPE, PA/PE, and PLA) and storage duration (6 and 14 days) have a great impact on the level of antioxidant compounds in the nettle leaves, where LDPE and BOPP can be highlighted as the most favorable for the preservation of total and individual phenolic compounds, photosynthetic pigments, and antioxidant capacity. [ABSTRACT FROM AUTHOR]

Hollyhock (Alcea rosea L.) is an aromatic, ornamental/medicinal plant species for which the selection of drought-tolerant varieties based on physio-chemical traits is desirable. The data presented resulted from a field experiment. This experiment was designed as a split-plot, based on a randomized complete block design, in which the main plots consisted of the three irrigation regimes (30, 60 and 80% permissible discharge moisture available in the soil), and the subplots consisted of nine hollyhock varieties. Photosynthetic pigments, Fv/Fm, proline content and selected antioxidant enzymes were measured throughout the period of induced drought stress. The data obtained illustrate the nature of the physiological response of hollyhock to drought stress. Based on the measured traits the varieties Isfahan 1, Shiraz 1 and Tabriz were shown to display the highest degree of resistance to drought stress. These data suggest that the effect of drought stress is dependent upon the drought level, variety and the trait in question. In this regard, future plant breeders for this species may find it useful to utilize ascorbate peroxidase (APX), catalase (CAT) and guayacol peroxidase (POX) activities as biochemical markers to select for drought-tolerant genotypes. As such, hollyhock can be considered a promising ornamental/medicinal species for cultivation in semi-arid environments. [ABSTRACT FROM AUTHOR]