Combined toxicity of zinc oxide nanoparticles and cadmium inducing root damage in Phytolacca americana L

Zinc oxide nanoparticles alleviated Cd toxicity in Hibiscus syriacus L. by reducing Cd translocation and improving plant growth and root cellular ultrastructure

Soil cadmium (Cd) contamination threatens plant growth and agricultural productivity. Hibiscus syriacus L., valued for its ornamental, edible, and medicinal properties, is widely cultivated in Cd-contaminated areas of southern China.This study aimed to evaluate the effectiveness of nano-zinc oxide (nZnO) in alleviating Cd toxicity in H. syriacus, examining plant phenotypes, physiological and biochemical responses, root ultrastructure, and the accumulation and distribution of Cd and Zn within the soil-H. syriacus system. Pot experiments included Cd treatment (100 mg/kg) and combined soil or foliar applications of nZnO (50 and 100 mg/L), with plants harvested after 45 days. Compared to Cd treatment alone, the combined application of nZnO significantly increased biomass in roots, stems, and leaves, improved photosynthetic performance, osmotic regulation, and antioxidant levels, and mitigated root cell damage; Cd concentrated mainly in roots, and nZnO reduced root Cd levels by 0.24 %-9.06 %. SEM-EDS observations revealed that Cd predominantly accumulated in the root epidermis and cortex, with Cd stress leading to increased levels and localized aggregation of Cd in the xylem. By contrast, nZnO treatment alleviated this disruption. Leaf application of 50 mg/L nZnO showed the best results. These findings highlight nZnO as a promising nano fertilizer for alleviating Cd stress in plants.

An Innovative Approach: Alleviating Cadmium Toxicity in Grapevine Seedlings Using Smoke Solution Derived from the Burning of Vineyard Pruning Waste

Although plant-derived smoke solutions (SSs) have exhibited growth-promoting properties in various plant species, their potential role in mitigating heavy metal stress, specifically in grapevines, has remained unexplored and unreported. This knowledge gap prompted the present study to evaluate the efficacy of foliar application of SSs derived from vineyard pruning waste at concentrations of 0%, 0.5%, 1%, and 2% in mitigating Cadmium (Cd) phytotoxicity in grape saplings. In our study, cadmium stress was induced by applying 10 mg/kg CdCl2 to the root area of the saplings, in conjunction with fertilizers. Our findings showed that exposure to Cd toxicity impeded the growth of grapevine saplings, adversely affecting shoot and root length, as well as fresh weight. Furthermore, it resulted in a reduction in chlorophyll content, stomatal conductance, and leaf water content while significantly increasing membrane damage and lipid peroxidation. Notably, the application of 0.5% SS enhanced grapevine sapling growth and alleviated Cd stress-induced damage by more effectively regulating physiological and biochemical responses compared to the control and other concentrations. Based on our results, under Cd stress conditions, the application of 0.5% SS effectively increased chlorophyll content, relative water content (RWC), stomatal conductance (1.79 mmol.m-2.sn-1), and total phenolic content (1.89 mg.g-1), whereas it significantly reduced malondialdehyde (MDA) levels and membrane damage (1.35 nmol.g-1). Additionally, it significantly elevated the activities of antioxidant enzymes, including superoxide dismutase (SOD) (2.16 U.mg-1), catalase (CAT) (1.55 U.mg-1), and ascorbate peroxidase (APX) (3.03 U.mg-1). The study demonstrated that plant-derived SS mitigates Cd stress in grapevines by enhancing antioxidative defence mechanisms.

Bridging agro-science and human nutrition: zinc nanoparticles and biochar as catalysts for enhanced crop productivity and biofortification

The integration of zinc nanoparticles (Zn NPs) with biochar offers a transformative approach to sustainable agriculture by enhancing plant productivity and human nutrition. This combination improves soil health, optimizes nutrient uptake, and increases resilience to environmental stressors, leading to superior crop performance. Our literature review shows that combining Zn NPs with biochar significantly boosts the crop nutrient composition, including proteins, vitamins, sugars, and secondary metabolites. This enhancement improves the plant tolerance to environmental challenges, crop quality, and shelf life. This technique addresses the global issue of Zn deficiency by biofortifying food crops with increased Zn levels, such as mung beans, lettuce, tomatoes, wheat, maize, rice, citrus, apples, and microgreens. Additionally, Zn NPs and biochar improve soil properties by enhancing water retention, cation exchange capacity (CEC), and microbial activity, making soils more fertile and productive. The porous structure of biochar facilitates the slow and sustained release of Zn, ensuring its bioavailability over extended periods and reducing the need for frequent fertilizer applications. This synergy promotes sustainable agricultural practices and reduces the environmental footprint of the traditional farming methods. However, potential ecological risks such as biomagnification, nanoparticle accumulation, and toxicity require careful consideration. Comprehensive risk assessments and management strategies are essential to ensure that agricultural benefits do not compromise the environmental or human health. Future research should focus on sustainable practices for deploying Zn NPs in agriculture, balancing food security and ecological integrity and positioning this approach as a viable solution for nutrient-efficient and sustainable agriculture.

Application of Zinc Oxide Nanoparticles to Mitigate Cadmium Toxicity: Mechanisms and Future Prospects

Cadmium (Cd), as the most prevalent heavy metal contaminant poses serious risks to plants, humans, and the environment. The ubiquity of this toxic metal is continuously increasing due to the rapid discharge of industrial and mining effluents and the excessive use of chemical fertilizers. Nanoparticles (NPs) have emerged as a novel strategy to alleviate Cd toxicity. Zinc oxide nanoparticles (ZnO-NPs) have become the most important NPs used to mitigate the toxicity of abiotic stresses and improve crop productivity. The plants quickly absorb Cd, which subsequently disrupts plant physiological and biochemical processes and increases the production of reactive oxygen species (ROS), which causes the oxidation of cellular structures and significant growth losses. Besides this, Cd toxicity also disrupts leaf osmotic pressure, nutrient uptake, membrane stability, chlorophyll synthesis, and enzyme activities, leading to a serious reduction in growth and biomass productivity. Though plants possess an excellent defense mechanism to counteract Cd toxicity, this is not enough to counter higher concentrations of Cd toxicity. Applying Zn-NPs has proven to have significant potential in mitigating the toxic effects of Cd. ZnO-NPs improve chlorophyll synthesis, photosynthetic efficiency, membrane stability, nutrient uptake, and gene expression, which can help to counter toxic effects of Cd stress. Additionally, ZnO-NPs also help to reduce Cd absorption and accumulation in plants, and the complex relationship between ZnO-NPs, osmolytes, hormones, and secondary metabolites plays an important role in Cd tolerance. Thus, this review concentrates on exploring the diverse mechanisms by which ZnO nanoparticles can alleviate Cd toxicity in plants. In the end, this review has identified various research gaps that need addressing to ensure the promising future of ZnO-NPs in mitigating Cd toxicity. The findings of this review contribute to gaining a deeper understanding of the role of ZnO-NPs in combating Cd toxicity to promote safer and sustainable crop production by remediating Cd-polluted soils. This also allows for the development of eco-friendly approaches to remediate Cd-polluted soils to improve soil fertility and environmental quality.

Plant-nano interactions: A new insight of nano-phytotoxicity

Whether nanoparticles (NPs) are boon or bane for society has been a centre of in-depth debate and key consideration in recent times. Exclusive physicochemical properties like small size, large surface area-to-volume ratio, robust catalytic activity, immense surface energy, magnetism and superior biocompatibility make NPs obligatory in many scientific, biomedical and industrial ventures. Nano-enabled products are newer entrants in the present era. To attenuate environmental stress and maximize crop yields, scientists are tempted to introduce NPs as augmented supplements in agriculture. The feasible approaches for NPs delivery are irrigation, foliar spraying or seed priming. Internalization of excessive NPs to plants endorses negative implications at higher trophic levels via biomagnification. The characteristics of NPs (dimensions, type, solubility, surface charge), applied concentration and duration of exposure are prime factors conferring nanotoxicity in plants. Several reports approved NPs persuaded toxicity can precisely mimic abiotic stress effects. The signature effects of nanotoxicity include poor root outgrowth, biomass reduction, oxidative stress evolution, lipid peroxidation, biomolecular damage, perturbed antioxidants, genotoxicity and nutrient imbalance in plants. NPs stress impels mitogen-activated protein kinase signaling cascade and urges stress responsive defence gene expression to counteract stress in plants. Exogenous supplementation of nitric oxide (NO), arbuscular mycorrhizal fungus (AMF), phytohormones, and melatonin (ME) is novel strategy to circumvent nanotoxicity. Briefly, this review appraises plants' physio-biochemical responses and adaptation scenarios to endure NPs stress. As NPs stress represents large-scale contaminants, advanced research is indispensable to avert indiscriminate NPs usage for synchronizing nano-security in multinational markets.

Zinc oxide nanoparticles influence on plant tolerance to salinity stress: insights into physiological, biochemical, and molecular responses

A slight variation in ecological milieu of plants, like drought, heavy metal toxicity, abrupt changes in temperature, flood, and salt stress disturbs the usual homeostasis or metabolism in plants. Among these stresses, salinity stress is particularly detrimental to the plants, leading to toxic effects and reduce crop productivity. In a saline environment, the accumulation of sodium and chloride ions up to toxic levels significantly correlates with intracellular osmotic pressure, and can result in morphological, physiological, and molecular alterations in plants. Increased soil salinity triggers salt stress signals that activate various cellular-subcellular mechanisms in plants to enable their survival in saline conditions. Plants can adapt saline conditions by maintaining ion homeostasis, activating osmotic stress pathways, modulating phytohormone signaling, regulating cytoskeleton dynamics, and maintaining cell wall integrity. To address ionic toxicity, researchers from diverse disciplines have explored novel approaches to support plant growth and enhance their resilience. One such approach is the application of nanoparticles as a foliar spray or seed priming agents positively improve the crop quality and yield by activating germination enzymes, maintaining reactive oxygen species homeostasis, promoting synthesis of compatible solutes, stimulating antioxidant defense mechanisms, and facilitating the formation of aquaporins in seeds and root cells for efficient water absorption under various abiotic stresses. Thus, the assessment mainly targets to provide an outline of the impact of salinity stress on plant metabolism and the resistance strategies employed by plants. Additionally, the review also summarized recent research efforts exploring the innovative applications of zinc oxide nanoparticles for reducing salt stress at biochemical, physiological, and molecular levels.

Nano-enabled agrochemicals: mitigating heavy metal toxicity and enhancing crop adaptability for sustainable crop production

The primary factors that restrict agricultural productivity and jeopardize human and food safety are heavy metals (HMs), including arsenic, cadmium, lead, and aluminum, which adversely impact crop yields and quality. Plants, in their adaptability, proactively engage in a multitude of intricate processes to counteract the impacts of HM toxicity. These processes orchestrate profound transformations at biomolecular levels, showing the plant's ability to adapt and thrive in adversity. In the past few decades, HM stress tolerance in crops has been successfully addressed through a combination of traditional breeding techniques, cutting-edge genetic engineering methods, and the strategic implementation of marker-dependent breeding approaches. Given the remarkable progress achieved in this domain, it has become imperative to adopt integrated methods that mitigate potential risks and impacts arising from environmental contamination on yields, which is crucial as we endeavor to forge ahead with the establishment of enduring agricultural systems. In this manner, nanotechnology has emerged as a viable field in agricultural sciences. The potential applications are extensive, encompassing the regulation of environmental stressors like toxic metals, improving the efficiency of nutrient consumption and alleviating climate change effects. Integrating nanotechnology and nanomaterials in agrochemicals has successfully mitigated the drawbacks associated with traditional agrochemicals, including challenges like organic solvent pollution, susceptibility to photolysis, and restricted bioavailability. Numerous studies clearly show the immense potential of nanomaterials and nanofertilizers in tackling the acute crisis of HM toxicity in crop production. This review seeks to delve into using NPs as agrochemicals to effectively mitigate HM toxicity and enhance crop resilience, thereby fostering an environmentally friendly and economically viable approach toward sustainable agricultural advancement in the foreseeable future.

Fulvic acid modified ZnO nanoparticles improve nanoparticle stability, mung bean growth, grain zinc content, and soil biodiversity

Zinc oxide nanoparticles (ZnO NPs) have emerged as a novel solution to combat Zn deficiency in agriculture. However, challenges persist regarding their Zn utilization efficiency and environmental impact. Fulvic acid (FA), as a relatively mature modified material, is a promising candidate to enhance the environmental stability of ZnO NPs. This study investigates modifying ZnO NPs with FA to improve their stability and increase Zn content in mung bean fruit and explores their effect on plants and the soil ecosystem. We combined FA and ZnO NPs (FZ-50) at mass ratios of 1: 5, 1: 2, and 4: 5, denoted as 20 % FZ, 50 % FZ, and 80 % FZ, respectively. Initial germination tests revealed that the 50 % FZ treatment improved sprout growth and Zn content and minimized agglomeration the most. A subsequent pot experiment compared FZ-50 with ZnO, ZnO NPs, and F + Z (1: 1 FA: ZnO NPs). Notably, the FZ-50 treatment (50 % FZ applied to the soil) demonstrated superior results, exhibiting a 30.25 % increase in yield, 121 % improvement in root nodule quality, and 56.38 % increase in Zn content, with no significant changes in enzyme activities (catalase and peroxidase). Furthermore, FZ-50 increased soil available Zn content and promoted soil microorganism diversity, outperforming ZnO and ZnO NPs. This study underscores the potential of FA as a relatively mature material for modifying ZnO NPs to increase grain Zn content, presenting a novel approach to addressing Zn deficiency in agriculture.

An Innovative Approach to Alleviate Zinc Oxide Nanoparticle Stress on Wheat through Nanobubble Irrigation

The extensive utilization of zinc oxide nanoparticles in consumer products and the industry has led to their substantial entry into the soil through air and surface runoff transportation, which causes ecotoxicity in agro-ecosystems and detrimental effects on crop production. Nanobubbles (diameter size < 1 µm) have many advantages, such as a high surface area, rapid mass transfer, and long retention time. In this study, wheat seedlings were irrigated with a 500 mg L-1 zinc oxide nanoparticle solution delivered in the form of nanobubble watering (nanobubble-ZnO-NPs). We found that nanobubble watering improved the growth and nutrient status of wheat exposed to zinc oxide nanoparticles, as evidenced by increased total foliar nitrogen and phosphorus, along with enhanced leaf dry mass per area. This effect can be attributed to nanobubbles disassembling zinc oxide aggregates formed due to soil organic carbon, thereby mitigating nutrient absorption limitations in plants. Furthermore, nanobubbles improved the capability of soil oxygen input, leading to increased root activity and glycolysis efficiency in wheat roots. This work provides valuable insights into the influence of nanobubble watering on soil quality and crop production and offers an innovative approach for agricultural irrigation that enhances the effectiveness and efficiency of water application.

Aluminum phytotoxicity in acidic environments: A comprehensive review of plant tolerance and adaptation strategies

Aluminum (Al), a non-essential metal for plant growth, exerts significant phytotoxic effects, particularly on root growth. Anthropogenic activities would intensify Al's toxic effects by releasing Al3+ into the soil solution, especially in acidic soils with a pH lower than 5.5 and rich mineral content. The severity of Al-induced phytotoxicity varies based on factors such as Al concentration, ionic form, plant species, and growth stages. Al toxicity leads to inhibited root and shoot growth, reduced plant biomass, disrupted water uptake causing nutritional imbalance, and adverse alterations in physiological, biochemical, and molecular processes. These effects collectively lead to diminished plant yield and quality, along with reduced soil fertility. Plants employ various mechanisms to counter Al toxicity under stress conditions, including sequestering Al in vacuoles, exuding organic acids (OAs) like citrate, oxalate, and malate from root tip cells to form Al-complexes, activating antioxidative enzymes, and overexpressing Al-stress regulatory genes. Recent advancements focus on enhancing the exudation of OAs to prevent Al from entering the plant, and developing Al-tolerant varieties. Gene transporter families, such as ATP-Binding Cassette (ABC), Aluminum-activated Malate Transporter (ALMT), Natural resistance-associated macrophage protein (Nramp), Multidrug and Toxic compounds Extrusion (MATE), and aquaporin, play a crucial role in regulating Al toxicity. This comprehensive review examined recent progress in understanding the cytotoxic impact of Al on plants at the cellular and molecular levels. Diverse strategies developed by both plants and scientists to mitigate Al-induced phytotoxicity were discussed. Furthermore, the review explored recent genomic developments, identifying candidate genes responsible for OAs exudation, and delved into genome-mediated breeding initiatives, isolating transgenic and advanced breeding lines to cultivate Al-tolerant plants.

Nanotoxicity assessment in plants: an updated overview

Nanotechnology is rapidly emerging and innovative interdisciplinary field of science. The application of nanomaterials in agricultural biotechnology has been exponentially increased over the years that could be attributed to their uniqueness, versatility, and flexibility. The overuse of nanomaterials makes it crucial to determine their fate and distribution in the in vitro (in cell and tissue cultures) and in vivo (in living species) biological environments by investigating the nano-biointerface. The literature states that the beneficial effects of nanoparticles come along with their adverse effects, subsequently leading to an array of short-term and long-term toxicities. It has been evident that the interplay of nanoparticles with abiotic and biotic communities produces several eco-toxicological effects, and the physiology and biochemistry of crops are greatly influenced by the metabolic alterations taking place at cellular, sub-cellular, and molecular levels. Numerous risk factors affect nanoparticle's accumulation, translocation, and associated cytogenotoxicity. This review article summarizes the contributing factors, possible mechanisms, and risk assessment of hazardous effects of various types of nanoparticles to plant health. The methods for evaluating the plant nanotoxicity parameters have been elaborated. Conclusively, few recommendations are put forward for designing safer, high-quality nanomaterials to protect and maintain environmental safety for smarter agriculture demanded by researchers and industrialists.

Soil pollution and the invasion of congener Sphagneticola in crop lands

The input of agro-pollutants, such as microplastics and nanopesticides, on farmlands is widespread and may facilitate biological invasions in agroecosystems. Here, the effects of agro-pollutants that promote invasion of congener species is studied by examining the growth performance of native Sphagneticola calendulacea and its invasive congener, S. trilobata, when grown in a native only, invasive only and mixed community. Sphagneticola calendulacea naturally occurs in croplands in southern China, while S. trilobata was introduced to this region and has since naturalized, encroaching onto farmland. In our study, each plant community was subjected to the following treatments: control, microplastics only, nanopesticides only, and both microplastics and nanopesticides. The effects of the treatments on soils of each plant community were also examined. We found that aboveground, belowground, and photosynthetic traits of S. calendulacea were significantly inhibited by the combined microplastics and nanopesticides treatment in the native and mixed communities. The relative advantage index of S. trilobata was 69.90% and 74.73% higher under the microplastics only and nanopesticides only treatments respectively compared to S. calendulacea. Soil microbial biomass, enzyme activity, gas emission rates, and chemicals in each community were reduced when treated with both microplastics and nanopesticides. Yet, soil microbial biomass of carbon and nitrogen, CO₂ emission rates and nitrous oxide rates were significantly higher (56.08%, 58.33%, 36.84% and 49.95% respectively) in the invasive species community than in the native species community under microplastics and nanopesticides. Our results suggest that the addition of agro-pollutants to soils favors the more resistant S. trilobata and suppresses the less tolerant S. calendulacea. Soil properties from the native species community are also more impacted by agro-pollutants than substrates supporting the invasive species. Future studies should explore the effects of agro-pollutants by comparing other invasive and native species and considering human activities, industry, and the soil environment.

Controlled synthesis and computational analysis of gold nanostars for the treatment of Fusarium oxysporum

Fusarium oxysporum (F. oxysporum) is linked to the widespread fusarium wilt in plants affecting the quality and yield of food crops. Management of fusarium wilt by synthetic fertilizers poses safety concerns. Safer-by-design nanomaterials synthesized with a greener approach can meet the needs of commercial antifungal drug resistance. Herein, a simple aqueous reduction method has been adopted for the synthesis of anisotropic gold nanostars (AuNSs) using quercetin-para aminobenzoic acid (QPABA) as both a reducing and stabilizing agent at room temperature for the treatment of F. oxysporum. QPABA was used to control the growth of Au³⁺ star-shaped nanoparticles at increasing concentrations in the ratio of 2 : 1 (QPABA : Au³⁺ ions) respectively. Transmission electron microscopy (TEM) analysis of the as-prepared gold nanoparticles confirmed the formation of nanostars with sizes of 40 ± 2 nm. The formation of anisotropic gold nanoparticles was evaluated by UV-vis characterizations which showed longitudinal surface plasmon modes at 540 and 800 nm. The gold nanoparticles exhibit excellent antifungal activity against F. oxysporum with the minimum inhibitory concentration (MIC) of 100 μg mL^-1 using an agar well-diffusion assay. AuNSs proved to be efficacious in controlling F. oxysporum, as shown in the SEM analysis with a disintegrated cell membrane upon treatment. Computational analysis was performed to determine the specific binding sites on the QPABA ligand for gold ion interactions using the DFT B3LYP method, with a 6-31+G(d) basis set. Results showed that the interaction between Au³⁺ and QPABA at the 4 and 3 positions yielded the highest stability and formation of gold nanostars. The results suggest that the synthesized AuNSs act as a promising antifungal agent with great potential in treating frequent fungal infections that affect agricultural production.

Co-exposure of maize to polyethylene microplastics and ZnO nanoparticles: Impact on growth, fate, and interaction

Microplastics (MPs), especially polyethylene MPs (PE MPs), which are the primary component of mulch, have attracted increasing attention in recent years. ZnO nanoparticles (NPs), which constitute a metal-based nanomaterial commonly used in agricultural production, co-converge with PE MPs in the soil. However, studies revealing the behavior and fate of ZnO NPs in soil-plant systems in the presence of MPs are limited. In this study, a pot experiment was used to evaluate the effects of maize co-exposure to PE MPs (0.5 % and 5 % w/w) and ZnO NPs (500 mg/kg) on growth, element distribution, speciation, and adsorption mechanism. The results demonstrate that individual exposure to PE MPs posed no significant toxicity; however, it significantly decreased maize grain yield (essentially 0). ZnO NP-exposure treatments significantly increased the Zn concentration and distribution intensity in maize tissues. Among them, the Zn concentration in the maize root exceeded 200 mg/kg, compared with 40 mg/kg in the grain. Moreover, the Zn concentrations in various tissues decreased in the following order: stem, leaf, cob, bract, and grain. Reassuringly, ZnO NPs still could not be transported to the maize stem under co-exposure to PE MPs. ZnO NPs had been biotransformed (64 % of the Zn was associated with histidine, with the remainder being associated with P [phytate] and cysteine) in maize stem. This study provides new insights into the plant physiological risks of PE MP and ZnO NP co-exposure in the soil-plant system and assesses the fate of ZnO NPs.

Zinc oxide nanoparticles improve lettuce (Lactuca sativa L.) plant tolerance to cadmium by stimulating antioxidant defense, enhancing lignin content and reducing the metal accumulation and translocation

Cadmium (Cd) contamination is a serious global concern that warrants constant attention. Therefore, a hydroponic study was conducted to evaluate the effect of different concentrations (0, 1, 2.5, 5, 10, 15 mg/l) of zinc oxide nanoparticles (ZnONPs) on the Cd content in lettuce (Lactuca sativa L.) under Cd stress conditions. The results showed that Cd stress triggered a decrease in plant biomass, an increase in relative electrolyte conductivity (REC), a decrease in root activity, accumulation of reactive oxygen species (ROS) accumulation, and nutrient imbalance. The application of ZnONPs reduced the toxicity symptoms of lettuce seedlings under Cd stress, with the most pronounced effect being observed 2.5 mg/l. ZnONPs promoted the growth of lettuce under Cd stress, mainly in terms of increase in biomass, chlorophyll content, antioxidant enzyme activity, and proline content, as well as reduction in Cd content, malondialdehyde, and reactive oxygen species (ROS) in plant tissues. ZnONPs also enhanced the uptake of ions associated with photosynthesis, such as iron, manganese, magnesium, and zinc. In addition, ZnONPs increase the amount of lignin in the roots, which blocks or reduces the entry of Cd into plant tissues.

Effect of Exogenous Application of Nicotinic Acid on Morpho-Physiological Characteristics of Hordeum vulgare L. under Water Stress

Abiotic stresses, such as high temperature and drought conditions, greatly influence the development of plants and the quality and quantity of products. Barley (Hordeum vulgare L.) crop production is largely impacted by drought, affecting growth, yield, and ultimately the productivity of the crop in hot arid/semi-arid conditions. The current pot experiment was directed to observe the outcome of nicotinic acid (NA) treatments on barley's physiological, biochemical, and production attributes at two capacity levels, i.e., 100% normal range and withholding water stress. Randomized complete block design (RCBD) was used during the experimentation with the two-factor factorial arrangement. NA was applied exogenously by two different methods, i.e., foliar and soil application (fertigation). NA solution contained various application levels, such as T1 = control, foliar applications (T2 = 0.7368 gL-1, T3 = 1.477 gL-1, T4 = 2.2159 gL-1), and soil applications (T5 = 0.4924 gL-1, T6 = 0.9848 gL-1, and T7 = 1.4773 gL-1). Results depicted that, overall, foliar treatments showed better effects than control and soil treatments. Plant growth was preeminent under T4 treatment, such as plant height (71.07 cm), relative water content (84.0%), leaf water potential (39.73-MPa), leaf area index (36.53 cm2), biological yield (15.10 kgha-1), grain yield (14.40 kgha-1), harvest index (57.70%), catalase (1.54 mmolg-1FW-1), peroxidase (1.90 g-1FWmin-1), and superoxide dismutase (52.60 µgFW-1) were superior under T4 treatment. Soil plant analysis development (54.13 µgcm-2) value was also higher under T4 treatment and lowest under T7 treatment. In conclusion, NA-treated plants were more successful in maintaining growth attributes than non-treated plants; therefore, the NA foliar treatment at the rate of 2.2159 gL-1 is suggested to find economical crop yield under drought conditions. The present study would contribute significantly to improving the drought tolerance potential of barley through exogenous NA supply in water deficit areas.

Phylogenomics Reveals the Evolutionary History of Phytolacca (Phytolaccaceae)

Phytolacca is the largest genus of Phytolaccaceae. Owing to interspecific hybridization, infraspecific variation, and apparent weak genetic control of many qualitative characters, which have obscured boundaries between species, the classification and phylogenetic relationships of this genus are unclear. Native Phytolacca is disjunctly distributed in America, eastern Asia, and Africa, and the biogeographic history of the genus remained unresolved. In this study, we used the whole chloroplast genome and three markers (nrDNA, rbcL, and matK) to reconstruct phylogenetic relationships within Phytolacca, analyze divergence times, and infer biogeographic histories. The phylogenetic results indicate that Phytolacca is monophyletic, which is inconsistent with the infrageneric classification based on morphology. According to the divergence time estimation, Phytolacca began to diversify at approximately 20.30 Ma during the early Miocene. Central America, including Mexico, Costa Rica, and Colombia, is the center of species diversity. Biogeographical analysis indicated five main dispersal events and Phytolacca originated from Central and South America. Birds may be the primary agents of dispersal because of the fleshy fruiting of Phytolacca. This study extended sampling and added more genetic characteristics to infer the evolutionary history of Phytolacca, providing new insights for resolving the classification and elucidating the dispersal events of Phytolacca.

Morpho-physiological growth performance and phytoremediation capabilities of selected xerophyte grass species toward Cr and Pb stress

Being sessile organisms, plants cannot escape unwanted changes in the environment. The rapid human population explosion caused significant environmental problems. Heavy metals produced through various sources can cause severe damage to living organisms. The study was planned to evaluate four grass species' morpho-physiological growth characteristics and phytoremediation capabilities under chromium (Cr) and lead stress (Pb) in the arid climate. Typha angustifolia, Tragus roxburghii, Aeluropus logopoides, and Cenchrus ciliaris grass species were used for the study. One-year-old stubbles from the Cholistan desert were used for the experiment. Cr treatments in the form of K₂Cr₂O₇ were applied at 0, 20, 40, and 80 mg L^-1, whereas Pb was applied as PbCl₂ at 0, 50, 200, and 500 mg L^-1 as control, low, moderate and high-stress, respectively. After 6 weeks of heavy metals treatments, plants were harvested and analyzed for growth performance and phytoremediation capabilities. Results depicted that, regarding morphological attributes, T. angustifolia performed better, followed by C. ciliaris; no clear pattern was observed for T. roxburghii and A. logopoides. The CO₂ assimilation rate (Co₂d) and water use efficiency (WUE) increased as the heavy metal stress increased in all species under both metals. In contrast, total chlorophyll content was higher under low stress. Other physiological parameters, such as relative humidity (RHd), net photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), leaf internal CO2 concentration (Ci) and membrane stability index (MSI) gradually decreased as the Cr, and Pb stress levels increased among all the species. Moreover, Cr and Pb absorption contents of T. angustifolia were higher than the other three species at each stress level. Overall, T. angustifolia thrived against heavy metals stress and showed higher biomass, maximum photosynthetic measurements, WUE and higher metal absorption among all the selected species. Results concluded that although all the selected species behaved fine under stress conditions, T. angustifolia performance was better; thus, it can be used to remediate the soil near industrial estates.