Heavy metals (HMs) contamination poses a significant threat to environmental matrices, particularly soil, which is essential for food security, agricultural productivity, and key ecosystem services. Understanding how crops respond to HMs is crucial for developing biomonitoring strategies to assess soil contamination and inform remediation efforts. Plants, including crops, exhibit a range of functional traits (FT) that can indicate HMs stress and contamination levels. In this study, we investigated the response strategies of Zea mays L. var. Limagrain 31455, widely cultivated throughout the region of Land of Fires, a critically polluted area of southern Italy, to different concentrations of Zn, Pb, and Cr, corresponding to moderate to severe soil contamination. Functional traits related to the photosynthetic machinery, including gas exchange, chlorophyll fluorescence and reflectance indices, were examined. Root morpho-histochemical analysis were also conducted to correlate early root alterations with any observed changes in these photosynthetic traits. Results revealed distinct response patterns: tolerance to Zn, without adverse effects on photosynthetic traits; resistance to Pb, mediated by increased RD and photoprotection through change in reflectance indices; and sensitivity to Cr highlighted by severe functional impairments of all the studied photosynthetic traits and structural root damages. Functional traits, such as chlorophyll fluorescence parameters and the photochemical reflectance index or normalized difference vegetation index, demonstrated high potential for monitoring HMs stress responses; in addition, morpho-anatomical traits of the root system provided insights into biomass allocation and the capacity of var. Limagrain 31455 to tolerate and adapt to HMs stress. These findings underscore the importance of integrating physiological, anatomical, and spectral analyses to improve the biomonitoring and management of polluted soils and detecting spatial variability in contamination via remote sensing.

Heliotropium L. genus belongs to the Boraginaceae family and is represented by approximately 250 species found in the temperate warm regions of the world, and there are 15 species of these species recorded in Turkiye. Heliotropium hirsutissimum Grauer grows in Bulgaria, Greece, N. Africa, Syria, and Turkiye. There is no record showing that H. hirsutissimum is a heat-tolerant plant. However, in our field studies, it was observed that H. hirsutissimum, which is also distributed in Hisaralan Thermal Springs of Sindirgi-Balikesir, Turkiye, grows in the thermal area with extremely high soil temperature (57.6 degrees C (similar to 60 degrees C)). It was thought that it would be useful to investigate the tolerance mechanism of the H. hirsutissimum plant to extremely high temperatures. For this purpose, the plant seeds were obtained from a geothermal area in the thermal spring. Growing plants were exposed to 20, 40, 60, and 80 +/- 5 degrees C soil temperature gradually for 15 days under laboratory conditions. We measured the effect of high soil temperature on some morphological changes, relative water content, thiobarbituric acid reactive substances, cell membrane stability, and hydrogen peroxide analysis to determine stress levels on leaves and roots. Changes in osmolyte compounds, some antioxidant enzyme activities, ascorbate content, and chlorophyll fluorescence and photosynthetic gas exchange parameters were also determined. As a result of the study carried out to determine the stress level, it was observed that there was not much change and it was understood that the plant was tolerant to high soil temperature. In addition, there was a general increase in osmolytes accumulation, antioxidant enzyme activities, and ascorbate level. There was no significant difference in photosynthetic gas exchange and chlorophyll fluorescence parameters of plants grown at different soil temperatures. The high temperature did not negatively impact the photosynthetic yield of H. hirsutissimum because this plant was found to enhance its antioxidant capacity. The increase in antioxidant activity helped reduce oxidative damage and protect the photosynthetic mechanism under high temperature conditions, while the significant increase in the osmolyte level helped maintain the water status and cell membrane integrity of plants, thus enabling them to effectively withstand high soil temperatures.

Due to the unregulated handling of e-waste, the co-existence of PBDEs and heavy metals in water bodies and soil has been detected with high frequency. However, the combined toxicity for aquatic creatures remains unclear. This study investigated the single and combined stress of BDE3 and copper on the photosynthesis and antioxidant enzyme system of Salvinia natans (L.). The results indicated that there were no negative effects on photosynthetic pigments under single stress of BDE3 or combined stress with copper. However, to deal with oxidative stress, antioxidant defense enzymes, including SOD and CAT, were activated in S. natans. SOD was sensitive in the first stage, while CAT activity was significantly increased until the end of 14 days of incubation. Malondialdehyde content increased significantly, which indicated that excessive reactive oxygen species from pollution of BDE3 or coexistence with copper could not be eliminated. BDE3 concentration in the aqueous phase declined with time, while copper was accumulated over time in S. natans, with BCF increasing to 0.31 +/- 0.073 at the end. Our study indicated that the co-existence of copper could exacerbate the damage caused by BDE3 to S. natans in aqueous environment.

This investigation explores the physiological modulation in Brassica oleracea var. italica (broccoli) in response to treatments with distinct nanoparticles and biochemical elicitors, including copper oxide (CuO), zinc oxide (ZnO), silver nitrate (AgNO3), chitosan, methyl jasmonate (MeJA), and salicylic acid (SA). The study evaluated parameters indicative of plant vitality and stress adaptability, namely chlorophyll a and b concentrations, carotenoid content, relative water content (RWC), and relative stress injury (RSI). The application of chitosan elicited the highest RWC (95.38%), demonstrating its efficacy in preserving cellular hydration under stress, with SA (92.45%) and MeJA (90.53%) closely following. Notably, SA minimized RSI (28.95%), highlighting its superior capacity for mitigating cellular damage under adverse conditions. Comparable stress-ameliorative effects were observed for ZnO and chitosan treatments, suggesting their roles in fortifying membrane integrity. In the context of photosynthetic pigment accumulation, MeJA exhibited the most pronounced effect, achieving maximal chlorophyll a (7.13 mg/g fresh weight) and chlorophyll b (2.67 mg/g fresh weight) concentrations, with SA and ZnO displaying substantial supportive effects. Conversely, AgNO3 treatment was largely ineffective, manifesting the lowest recorded chlorophyll and carotenoid levels across all experimental conditions. Collectively, the findings underscore the potential of MeJA, SA, and chitosan nanoparticles as potent modulators of broccoli's physiological processes, particularly in enhancing photosynthetic efficiency, maintaining water balance, and mitigating oxidative damage under stress conditions. However, before field application, limitations such as the uncertain long-term effects of nanoparticles on plant genomic stability and soil ecosystems, the need for field validation under variable environmental stresses, and the economic feasibility for small-scale farmers must be addressed. Future research should focus on elucidating the molecular mechanisms behind nanoparticle-mediated stress tolerance, conducting eco-toxicity assessments of nanomaterials in agricultural systems, and optimizing cost-effective delivery methods.

Introduction Arbuscular mycorrhizal fungi (AMF) show significant potential for improving plant tolerance to vanadium (V) stress. However, the pattern and physiological mechanisms behind this effect are not fully understood.Methods To investigate this, we used green foxtail (Setaria viridis) as a test plant and inoculated this plant with (+AMF) or without (-AMF) Rhizophagus irregularis. These +AMF and -AMF plants were grown in soils with low (150 mg kg-1), medium (500 mg kg-1), and high (1000 mg kg-1) V pollution levels.Results Our results showed root colonization of +AMF plants, whereas no such colonization was observed in -AMF plants. Compared to -AMF plants, +AMF plants showed a more organized arrangement of leaf cells, intact chloroplasts, fewer starch granules, and an intact nuclear membrane. AMF increased leaf chlorophyll a concentration by 49% under high V pollution and that of chlorophyll b by 18% under low V pollution and 36% at medium soil V levels. AMF reduced the concentration of malondialdehyde (MDA) by 36%-40% in leaves and increased the activities of superoxide dismutase (SOD) by 20%-84%, catalase (CAT) by 5%-13%, and peroxidase (POD) by 12%-16%. +AMF plants exhibited 13%-32% greater plant height, 17%-23% longer root length, 42%-78% higher shoot biomass, 61%-73% greater root biomass, 16% increased root-to-shoot ratio (at high V pollution), and 7%-13% elevated leaf phosphorus concentration than -AMF plants. Furthermore, +AMF shoots had 16%-30% lower V concentrations than -AMF plants while +AMF roots exhibited 52%-73% smaller V concentrations than the -AMF control.Discussion These results suggest that AMF increase plant tolerance to V stress by protecting leaf ultrastructure, increasing chlorophyll concentration, reducing oxidative damage as well as biomass-driven V dilution and these effects of AMF were independent of soil V concentrations.

Drought stress is becoming a structural phenomenon in cropping systems challenged by climate change and soil fertility degradation. A balanced fertilization strategy based on nitrogen, phosphorus, and potassium as well as on silicon supplementation was tested as an efficient practice to improve maize tolerance to short-term drought stress. Three fertilization strategies (control: treatment with zero NPK fertilizer application; NPK: granular NPK fertilizer, and NPK + Si: granular NPK fertilizer enriched with 5% silicon) were evaluated under three irrigation regimes simulating three probable water deficit levels in the Mediterranean climate (I1, well-watered conditions: 80% of soil field capacity; I2, medium drought stress: 60% of soil field capacity; and I3, severe drought stress: 30% of soil field capacity). Drought stress was applied at V10 growth stage of maize and maintained for 15 days, then plants were rewatered according to the optimal irrigation regime. Results showed that medium and severe drought stress down-regulated maize plant growth and yield, especially under nutrient deficient conditions (control). Plants amended with NPK and NPK + Si recorded higher chlorophyll a pigment content (+ 22 to + 64%), stomatal conductance (+ 6 to 24%), and leaf relative water content (+ 7 to 23%) than those of the control, depending on the drought stress level. Silicon supplementation attenuated the down-regulation effects of drought stress on maize photosynthesis and biomass accumulation by improving stomatal conductance and electron transfer efficiency between PSII and PSI. Silicon supply improved the performance index for energy conservation from photons absorbed by PSII to the reduction of intersystem electron acceptors (PIabs) and reduced the dissipation energy flux (DIo/RC), responsible for the protection of PSII from photo-damage under drought stress, which resulted in significant enhancement of maize photosynthesis recovery and grain yield (+ 59 to 69%). Findings from the present study demonstrate that granular NPK-fertilizer fortified with silicon could be an efficient strategy to increase maize photosynthesis performance, plant growth, and productivity under short-term drought stress conditions.

Heavy metal contamination in agricultural soils is a growing environmental concern, particularly due to the increasing accumulation of cadmium (Cd) and chromium (Cr) from industrial discharge, wastewater irrigation, and excessive fertilizer use. These toxic metals severely impact crop productivity by disrupting nutrient uptake, damaging root structures, and inducing oxidative stress, which collectively inhibit plant growth and development. Maize (Zea mays L.), a globally important cereal crop, is highly susceptible to heavy metal toxicity, making it essential to develop cost-effective and sustainable mitigation strategies. Spent mushroom substrate (SMS) biochar has emerged as an effective and sustainable method due to its ability to absorb heavy metals. Spent mushroom substrate biochar improves compost quality, soil fertility, and health. Its high porosity and surface area immobilize toxic metals, reducing nutrient losses and oxidative stress in plants. Pyrolysis temperature affects its surface area, nutrient composition, and adsorption abilities. This study aims to address this gap by evaluating the effectiveness of SMS biochar at varying application rates in mitigating Cd and Cr toxicity in maize. By assessing key physiological and agronomic parameters, this research provides novel insights into the potential of SMS biochar as a sustainable soil amendment for heavy metal-contaminated soils. Five treatments, i.e., 0, 50, 100, 150 and 200B were applied under Cd and Cr toxicity in 3 replications following the completely randomized design (CRD). Results exhibited that 200B caused an increase in maize plant height (26.1%), root dry weight (99.7%), grain yield (98.2%), and chlorophyll contents (50%) over control under Cd and Cr stress. In conclusion, 200B can mitigate Cd and Cr stress in maize plants. More investigations are suggested to declare 200B as a promising amendment for mitigation of Cd and Cr stress in other crops.

Tetracycline (TC) antibiotics are one of the class of drugs widely used in clinical practice but also constitute a significant environmental concern. However, the adverse effects of TC on non-target organisms have not been well studied. The aim of this study was to examine the influence of exposure to high levels of TC on thalli of lichens to determine the impact on (1) physiological parameters including integrity of cell membranes, photosynthetic efficiency and viability, (2) oxidative stress response such as membrane lipid peroxidation, and (3) enzymatic antioxidant activities as catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR). Data demonstrated that exposure to tetracycline did not markedly affect the lichen membrane damage as indicated by no change in conductivity. This antibiotic diminished the potential photosystem II efficiency (FV/FM) indicating enhanced susceptibility as evidenced by lower chlorophyll fluorescence and chlorophyll content. The viability of lichens exposed to high concentrations of tetracycline was significantly reduced. The concentrations of thiobarbituric acid reactive substances were markedly elevated with increasing concentrations of antibiotics. At higher TC concentrations, 500 mg/L SOD activity was significantly elevated. In the case of CAT, APX and GR, TC at higher concentrations significantly decreased these enzymic activities. The findings of this study contribute to the knowledge that TC antibiotics exert adverse ecotoxicological effects on lichens at high concentrations and provided a better understanding of the mechanisms underlying toxicity. Data also indicates that lichens may serve as an effective biomonitoring species for TC antibiotic exposure.

This study aimed to evaluate the synergistic effects of zinc sulfate and Pseudomonas spp. in terms of mitigating drought stress in maize (Zea mays L.) by analyzing physiological, biochemical, and morphological responses under field conditions. A two-year (2018-2019) field experiment investigated two irrigation levels (optimal and moderate stress) and twelve treatment combinations of zinc sulfate application methods (without fertilizer, soil, foliar, and seed priming) with zinc-solubilizing bacteria (no bacteria, Pseudomonas fluorescens, and Pseudomonas aeruginosa). Drought stress significantly reduced chlorophyll content, increased oxidative damage, and impaired membrane stability, leading to a 42.4% increase in electrolyte leakage and a 10.9% reduction in leaf area index. However, the combined application of zinc sulfate and P. fluorescens, and P. aeruginosa mitigated these effects, with seed priming showing the most significant improvements. Specifically, seed priming with zinc sulfate and P. fluorescens increased catalase activity by 76% under non-stress conditions and 24% under drought stress. Principal component analysis revealed that treatments combining zinc sulfate and P. fluorescens, and P. aeruginosa were strongly associated with improved chlorophyll content, carotenoid content, and grain yield while also enhancing osmotic adjustment and antioxidant enzyme activity. These findings highlight the potential of the use of zinc sulfate and P. fluorescens as well as P. aeruginosa as sustainable strategies for enhancing maize drought tolerance, mainly through seed priming and soil application methods.

Water deficit has a negative effect on the physiological aspects of plants, such as stomatal closure and consequent decline in photosynthetic carbon assimilation. Numerous water deficit mitigation strategies have been investigated, such as the use of bioregulators to minimize the damage caused. This study aimed at assessing the effects of brassinosteroids on the physiological aspects of a & ccedil;a & iacute; seedlings in inducing drought tolerance. The experiment was conducted using two water conditions (well-watered and water-deficit plants) and three brassinosteroid concentrations (0, 0.05 and 0.10 mu M of 24-epibrassinolide-EBL), with six repetitions. At 120 days, seedlings were transplanted to pots and watered, leaving the soil near field capacity for 56 days. Next, a group of plants were well-watered, and another submitted to water deficit for 18 days. Water deficit reduced gas exchange and photosynthetic efficiency with a lower decrease at EBL concentrations of 0.05 and 0.10 mu M, while larger declines were observed in plants without EBL. Relative water content and leaf succulence were maintained in water-deficit plants, while proline content rose, mainly with 0.10 mu M of EBL. Applying EBL also improved water use efficiency and maintained the leaf chlorophyll and stem dry matter of stressed plants. It was concluded that leaf brassinosteroid application alleviate of harmful effects of water deficit in young a & ccedil;a & iacute; plants, promoting proline accumulation, which increases water use efficiency, and maintaining photosynthetic pigments and water status, contributing to improving drought tolerance in a & ccedil;a & iacute;.