Improving nutrient use efficiency and minimizing environmental pollution from excessive fertilization require appropriate nutrient management supported by continuous monitoring of soil nutrient levels during crop growth. As only a few real-time sensors for the measurement of soil nutrients are available, this study evaluated the potential of electrical conductivity (EC) sensors, which reflect the ionic concentrations of the soil solution, for real-time estimation of plant-available nutrient levels. Nitrogen and potassium were sequentially supplied to achieve cumulative application rates of 25-300% of the nutrient uptake-based fertilization rate. The relationship between cumulative fertilization rate and accumulated sensor-based EC increase was described using linear, polynomial, and nonlinear saturation models. Sensor EC increased linearly from 25 to 125% of the nutrient uptake-based fertilization rate, while higher application rates were better explained by the nonlinear saturation equation. Sensor-based EC showed strong correlation with soil ammonium nitrogen (NH4+-N), indicating that the sensor effectively reflected nutrient dynamics. In open-field pepper soil, fertigation-induced increases in sensor EC followed the patterns predicted by both the linear and nonlinear saturation models established in the laboratory. These results demonstrate that EC sensors can be used for real-time monitoring of soil nutrient levels and may contribute to efficient nutrient management in open-field cultivation.

Nitrogen (N) and phosphorus (P) are essential nutrients that play critical roles in plant physiological processes and the accumulation of N and P in broccoli head was significantly correlated with yield. Therefore, there is a need for a rapid, non-destructive diagnosis of crop status by detecting deficiencies in essential nutrients. This study evaluated the effects of N and P deficiency on field grown broccoli (Brassica oleracea L. var. italica Plenk) using a plant-induced electrical signal (PIES) sensor, in which needle electrodes are inserted into the stem to measure electrical conductivity reflecting plant water and ion status. Four treatments were established, including the control (N100P100) with sufficient N and P supply, N deficiency (N0P100), P deficiency (N100P0), and combined N-P deficiency (N0P0). For sufficient supply, urea and fused phosphate (FP) were applied at rates of 122 kg N ha-1 and 71 kg P ha-1, respectively. Soil, stem, and leaf nutrient contents, growth parameters, and stress related indicators were analyzed and their relationship with PIES values were evaluated. PIES was highest in control (N100P100) and lowest under N-P deficiency (N0P0). Higher PIES values were observed during the vegetative stage, whereas values declined during the reproductive stage, reflecting changes in physiological activity. Growth parameters such as shoot and root weight and stem diameter were generally superior in the control (N100P100) treatment, while leaf calcium (Ca), magnesium (Mg), and potassium (K) concentrations showed no significant differences among treatments. Total N content in leaves was higher in N fertilized treatments (control and P deficiency). Photosynthesis-related parameters, including soil plant analysis development (SPAD), Fv/Fm, and chlorophyll content, were lowest under N-P deficiency, which was reflected in the PIES. Principal component analysis (PCA) showed that the PIES was closely associated with growth and photosynthetic parameters and clearly distinguished N sufficient treatments (control and P deficiency) from N deficient treatments (N0P100, N0P0). Overall, these findings suggest that PIES monitoring can serve as a sensitive physiological indicator of nutrient stress and may be applied as an early diagnostic tool before visible growth inhibition occurs in broccoli cultivation.

Particulate matter (PM) deposited on leaves reflects the quantity and chemical composition of atmospheric pollutants. The study investigated the seasonal variation in PM accumulated on the leaves of different roadside tree species (Chionanthus retusus, Ligustrum obtusifolium, Zelkova serrata, Acer palmatum, and Pinus densiflora) and the associated metal concentrations in different sizes of PM. The amount of PM accumulated on leaf surface was the lowest in summer (August) and increased in autumn (October), which was related to atmospheric PM concentration. The PM accumulation on leaves was influenced by rainfall and the duration of leaf exposure to the atmosphere. Pinus densiflora showed the highest PM accumulation across all seasons, with little seasonal variation in total amount of PM. Nickel, Zn, Cu, and Pb concentrations in PM>10 ranged from 23 to 215, 495 to 2694, 99 to 462, and 29 to 115 mg/kg, respectively, while those in PM2.5–10 ranged from 14 to 95, 210 to 817, 65 to 214, and 5.3 to 54 mg/kg. Metal concentrations in leaves varied, with Zn (26–929 mg/kg) being the most abundant metal, followed by Cu (6.1–100 mg/kg), Ni (0.95–58 mg/kg), and Pb (0.86–20 mg/kg). Metal concentrations in leaves were the lowest in spring and increased in summer and autumn. Adjacent soil samples beneath the tree canopy showed significant differences in metal concentrations despite their spatial proximity. The highest metal concentrations in soil were detected beneath Pinus densiflora, which may be influenced by inputs from PM accumulated on leaves via litterfall or wash-off. Strong positive correlations were found between metal concentrations in PM, soil and leaves, indicating potential bidirectional interactions and PM-associated leaf metal uptake.

Crops exhibit diverse growth characteristics influenced by environmental conditions, nutrient inputs, and climate, necessitating adaptive fertilizer management strategies. This study developed crop growth models for green onions (Sinheukgeumjang) and evaluated three fertigation strategies to optimize nutrient application under field conditions. Growth data from a quantitative fertigation control system were fitted using Logistic, Gompertz, and Double Logistic models via the Levenberg–Marquardt algorithm. Model performance was assessed using the coefficient of determination (R²) and Akaike Information Criterion (AIC), and stratified bootstrap resampling quantified parameter uncertainty. Three fertigation regimes were compared: (1) uniform fertigation, distributing nutrients evenly across the growth period; (2) proportional fertigation, allocating fertilizer according to the growth curve slope; and (3) model-informed dynamic fertigation, an enhancement of the proportional approach that integrates real-time soil electrical conductivity (EC) monitoring to adjust nutrient application rates according to both modeled growth and current field conditions. Field implementation in 2024 showed that Model-informed Dynamic Fertigation System (MIDFS) significantly improved plant length and yield compared with the other approaches. MIDFS improved plant growth and yield by approximately 14–15

Soil contamination with toxic metal(loid)s such as arsenic (As), cadmium (Cd), and lead (Pb) poses serious health risks by metal(loid) accumulation in crops. Biochar (BC) is a porous material that immobilizes metal(loid)s and modification of biochar further enhances its immobilization efficiency. Modified biochar (MBC) with iron phosphate can simultaneously immobilize As, Cd, and Pb in soil, as As is immobilized by iron oxides while Cd and Pb are immobilized by phosphate. Therefore, the purpose of this study was to evaluate and compare the effectiveness of BC and MBC in immobilizing metal(loid)s in contaminated soil and promoting the growth of lettuce. Both BC and MBC were applied to soils contaminated with either single or mixed metal(loid)s, including As, Cd and Pb. Shoot dry weight of lettuce grown in mixed metal(loid)-contaminated soil increased by 60.7

Minerals containing iron (Fe) and phosphate can simultaneously immobilize cations such as lead (Pb) and oxyanions including arsenic (As) and antimony (Sb). However, phosphate released from these minerals substitutes for adsorbed As and Sb and increases metal(loid) mobility, which limits their practical effectiveness. Vivianite [Fe3(PO4)2·8(H2O)], an Fe-phosphate mineral with low phosphate release potential, offers a promising solution for the simultaneous stabilization of cationic and anionic contaminants. This study evaluated the effectiveness of vivianite for concomitant immobilization of arsenite [As(III)], arsenate [As(V)], antimonite [Sb(III)], antimonate [Sb(V)], and Pb(II) in single- and mixed-metal(loid) solutions and contaminated soils. The adsorption of As(III), As(V), and Sb(III) onto vivianite followed the Langmuir isotherm model, indicating monolayer surface interaction. In mixed-metal(loid) solutions containing As or Sb with Pb, immobilization increased by 73

Nutrients and water in a greenhouse should be supplied in appropriate amounts to support proper growth of the plants. Supplying nutrient solutions based on solar radiation can lead to over-application of nutrients relative to plant uptake, potentially causing nutrient imbalance or inefficient fertilizer use. Therefore, the study investigated the effects of reducing electrical conductivity (EC) of nutrient solution on the growth, fruit quality, and nutrient use efficiency (NUE) of cherry tomatoes in a smart farm system. Cherry tomatoes were cultivated under two irrigation treatments, with the decreased EC treatment maintained at 2.0-2.5 dS m− 1 and the conventional EC treatment following conventional practices at 3.0-3.5 dS m− 1. The plant-induced electrical signal (PIES), which reflects plant vitality and water uptake, was higher in the decreased EC treatment. The partial factor productivity (PFP), indicating fertilizer use efficiency, was approximately 38.7

Soil contaminated with trivalent chromium (Cr3+) induced manganese (Mn) mobilization potentially leading to increased ecological toxicity. Although Cr3+ is relatively immobile in soil, its interaction with soil minerals indirectly increases Mn bioavailability, which poses risks to soil organisms. The objective of this study was to assess the bioavailability and potential ecological toxicity of Mn and Cr in Cr3+ contaminated soil using chemical extractions, earthworm (Eisenia fetida) toxicity tests, and dehydrogenase activity (DHA) as bioindicators. The mitigation of Mn toxicity in Cr contaminated soil was evaluated following amendments with biochar and calcium carbonate (CaCO3). Both amendments increased soil pH and reduced bioavailable Mn concentrations by 44-100% through sorption and pH induced immobilization. While bioavailable Cr concentrations also decreased, the effect was less significant because Cr was originally immobile in the soil. Earthworm survival and loss in biomass was not significantly affected by biochar treatment. Dehydrogenase activity was enhanced in biochar and CaCO3 amended soils, indicating improved microbial activity. Principal component analysis confirmed that biochar and CaCO3 amendments reduced bioavailability and metal toxicity to levels comparable to uncontaminated soils. The assessment of bioavailability through chemical extraction and toxicity using earthworm and DHA showed similar trends in this experiment. However, high amounts of biochar may negatively affect earthworms, and a holistic approach is required to effectively evaluate amendments for mitigating metal toxicity in soils.

The widespread use and improper disposal of plastics in the environment lead to microplastic (MP) pollution. Polyethylene terephthalate (PET) plastics are widely used as single-use plastics, and the mass use of these plastics is contaminating aquatic and terrestrial environments. The transportation of those plastic fragments on agricultural land increases the risk to crop production and food safety. Therefore, the study aimed to evaluate the effect of polyethylene terephthalate microplastics (PET-MPs) on plant growth, nutrient uptake, and physiological stress responses. A short-term effect of PET-MPs (0.1 g/L) on plant growth was assessed using radish (Raphanus sativus) and carrot (Daucus carota var. sativa) grown in half-strength Hoagland solution for one week. PET-MPs did not significantly affect plant biomass and nutrient uptake by plants. Micronutrients such as Cu, Fe, Mn, and Zn were mostly increased in roots and decreased in shoot samples of both plants with PET-MP treatment compared to the control. Although short-term exposure of plants to PET-MPs did not significantly affect plant biomass and nutrient uptake, a significant difference was observed in the physiological stress responses. Chlorophyll a and b contents were significantly (p < 0.05) decreased in radish leaves after PET-MP treatment. Malondialdehyde (MDA) content in the leaves of radish plants significantly increased, indicating that the plant was facing abiotic stress in PET-MP treatment. This study advances understanding of MP-induced phytotoxicity and highlights its potential implications for food safety in agroecosystems.

Although manganese (Mn) is essential element for plants, increasing Mn mobility caused by trivalent chromium [Cr(III)] in soil can be toxic to plants. Therefore, the study aimed to evaluate the stabilizing effects of chicken manure-derived biochar and lime (CaCO3) on Mn and Cr in sandy loam and loam soils treated with Cr(III), and to investigate the effects on growth and physiological responses of lettuce (Lactuca sativa). Biochar and lime application significantly reduced extractable Mn and Cr concentrations, increased soil pH and reduced Mn uptake in lettuce. In addition, biochar contributed to the alleviation of toxicity and the improvement of plant health. Lime also effectively reduced Mn accumulation in both shoots and roots, but increased Cr uptake in root. In both treatments, biochar limited translocation of Mn from root to shoot. Therefore, the phytotoxicity of Mn induced by Cr(III) spiking can be effectively mitigated by applying biochar to the soil.

Farmers use plastic mulching films to suppress weeds and protect plants from biotic and abiotic stresses; however, these films can become a source of microplastics in ecosystems. To better understand how plastic film-derived microplastics influence the rhizosphere microbiome and plant health, we examined the effects of plastic residues on Arabidopsis thaliana grown in treated soils. Plastic residues (≥5 mm) were mixed with agricultural soils at 5% (w/w) and incubated at 25 °C and 80% relative humidity in the dark for 120 d to allow microbial community stabilization. Neither the presence of plastics, soil incubation, nor their interaction significantly affected seedling growth or flowering time. However, rhizobacterial compositions were significantly changed by plastic treatment, incubation, and their interaction, despite no change in the α-diversity within each bacterial community tested in this study. Notably, the abundance of bacterial families, such as Alcanivoracaceae, Cytophagaceae, and Latescibacteraceae, shifted in response to plastic. Additionally, changes in the microbiome and treatment conditions induced transcriptional alterations in genes involved in photosynthesis, nitrogen assimilation, and the response to oxidative stress. These findings suggest that plastic residues in soil indirectly affect the bacterial community and plant gene expression; thus, their interaction should be considered to maintain sustainable agroecosystems.

Comparative evaluation of defence responses in different Arabidopsis ecotypes to pathogens is useful for understanding how plants acquire disease resistance and finding valuable genetic resources for disease resistance. In this study, leaf chlorosis was delayed in Arabidopsis ecotype Dijon-G (Di-G) in response to Xanthomonas campestris pv. campestris (Xcc) 8004 infection, as well as continuous darkness compared to the ecotype Columbia-0 (Col-0). However, Xcc bacterial proliferation within Di-G was slightly higher in Col-0. The Xcc infection led to lower expression of several pathogenesis-related genes (PDIOX, GLIP1 and PAD4) and senescence-related genes (DIN6 and SAG12) in Di-G. Dark-induced leaf senescence was delayed in detached Di-G leaves, showing a higher chlorophyll content than that of Col-0. Exogenous SA did not change the chlorophyll loss in the Xcc-inoculated Col-0 or Di-G leaves, but SA limited Xcc growth in Col-0 but not in Di-G. SA pretreatment compromised chlorophyll loss in Col-0 during dark-induced leaf senescence, but it remained unaltered in Di-G. These results show that Di-G may have more efficient machinery for attenuating chlorophyll degradation during Xcc bacterial infection and continuous darkness than Col-0. The different sensitivities to exogenous SA in Col-0 and Di-G suggest that the two ecotypes have adapted differently to their natural habitats in terms of plant immunity and leaf senescence.

Metal contamination poses serious environmental and human health risks, which results in the need for low-cost remediation approaches. The utilization of agricultural byproducts for the removal of metal contaminants is considered cost-effective and environmentally sustainable. Garlic byproducts are rich in sulfur-containing compounds, and various functional groups contribute to metal binding. This study aimed to evaluate the potential of garlic stem and peel for the removal of cadmium (Cd), lead (Pb), and arsenic (As) from aqueous solutions and for their immobilization in contaminated soils. Batch sorption experiments conducted at pH 7 for 24 h showed that garlic stem removed 71.5% of Cd and 70.8% of Pb, while garlic peel achieved 65.4% and 79.4% removal, respectively. The higher Pb removal by garlic peel might be attributed to its higher sulfur content. However, both byproducts were less effective in removing As(III) and showed negligible removal of As(V), as these species predominantly occur in neutral or negatively charged species at neutral pH, resulting in weak interactions with negatively charged surface functional groups. Soil incubation experiments were conducted using 1% and 5% amendments of garlic stem and peel in Pb- and As-contaminated soils. Extractable Pb concentrations significantly increased in soils treated with 1% garlic peel because of the formation of labile complexes of Pb with dissolved organic carbon. However, a column experiment to evaluate the impact on Pb mobility under saturated and unsaturated conditions showed that Pb concentration in soil pore water decreased with garlic stem. Pb concentration was lower under saturated conditions, possibly due to the precipitation of Pb as PbS. Although the short-term application of raw agricultural byproducts increased extractable metal concentrations, long-term incubation reduced Pb levels in pore water. These findings suggest that unmodified garlic stem is a promising, cost-effective amendment for Pb immobilization in soil. Nevertheless, caution is needed in its application to prevent unintended metal mobilization in soil.

Plants are the major reservoir of bioactive compounds such as flavonoids, phenolics, proanthocyanidins, alkaloids, terpenoids, saponins, glycosides, essential oils, carotenoids, and natural dyes, some of which demonstrate bioactive properties. Bioactive compounds play a vital role in the food, fragrance, cosmetic, textile, and pharmaceutical sectors. Globally, the demand for plants as a whole and plant-based biomolecules is increasing to treat human diseases effectively. However, conventional production methods are time-consuming and fail to meet market demand. Recently, researchers have been exploring the potential of nanoparticles (NPs) as novel elicitors for increasing the levels of industrially important bioactive compounds in plants. Nanoparticles can be categorized into metallic, metal-oxide, non-metallic, bimetallic, and nanocomposites. Nanoparticles trigger the synthesis of reactive oxygen species (ROS), resulting in the upregulation of secondary metabolism to enhance bioactive compound synthesis. This review systematically discusses recent advancements in NPs assisted elicitation of bioactive plant metabolites in both in vitro and in vivo systems. The role of NPs in enhancing the production of secondary metabolites (SMs) has been comprehensively examined across various culture conditions. Several NPs, including silver, gold, zinc, cobalt, nickel, cerium, and aluminum, have shown promise as effective elicitors for boosting SM levels. However, some studies have reported phytotoxic effects, negatively affecting plant growth and SM accumulation. Accordingly, this review also highlights the potential adverse effects of NPs on plant systems and discusses the challenges associated with scaling up this technology. Overall, NPs present a novel and promising strategy for enhancing SM production in plants for industrial, pharmaceutical, and other applications.

Long-term exposure of plastics to the environment causes them to disintegrate, resulting in the formation of micro/nanoplastics as well as the release of additives and chemicals into the soil. The micro/nanoplastics are able to readily migrate into the soil, destabilize the soil microbiota, and finally enter crop plants. Endocytosis, apoplastic transport, root adsorption, transpiration pull, stomatal entry, and crack-entry mode are well-known pathways by which microplastics enter into plants. Roots of vegetable crops were able to transfer 0.2 µm–1.0 µm of microplastics through root adsorption and by transpiration pull to the xylem and then further transported them to the plant tissues through apoplastic pathways. Beads of 1000 nm size were also engulfed by BY-2 protoplast cells through endocytosis. Micro and nanoplastics that enter crops affected the physiological and biochemical activities of the plants. Aquaporins were needed to aid the symplastic pathway which made the symplastic pathway difficult for MPs/NPs transport. Microplastics block seed capsules and roots of seedlings, thereby negatively affecting the uptake and efficient use of nutrients supplied. Photosynthesis of plants was affected due to the reduction in chlorophyll contents. Exposing soils to MPs/NPs drastically affected the pH, EC, and bulk density of the soil. This review focused on bridging the knowledge gap with understanding how microplastics prevent nutrient uptake and nutrient use efficiency in plants. This understanding is essential for assessing the broader ecological impacts of plastic contamination and for developing effective mitigation strategies. Further research is needed on microorganisms capable of degrading plastics, as well as on developing analytical methods for detecting plastics in soil and plant tissues. Also, further research on how to replace plastic mulching and still provide the same benefits as plastic mulch is needed.

Soil contamination with metalloids such as arsenic (As) and antimony (Sb) and heavy metals such as lead (Pb) in agricultural area surrounding mines affects growth of crops. Because As and Sb are stabilized by iron (Fe) hydroxide and heavy metals are stabilized by phosphate, iron phosphate-coated biochar (IPCB) simultaneously stabilizes metal(loid)s and prevents detrimental effect of metal(loid)s on crops. Therefore, the objective of the study was to evaluate lettuce growth followed by metal stabilization in soil by treating metal contaminated soil with IPCB. The lettuce grown in single and mixed metal(loid)-contaminated soil treated with IPCB showed higher dry biomass, chlorophyll content measured by soil plant analysis development (SPAD) meter, and Fv/Fm values than without IPCB indicating that IPCB mitigated toxic effect of metal(loid)s. The IPCB decreased bioavailable As, Sb, and Pb by 40.8 ± 3.0

Soil around mines contaminated with metal(loid) is not suitable for growing plants and it is necessary to select indigenous plants with tolerance for metal(loid) and ameliorate metal toxicity in soil using soil amendments. Therefore, the purpose of this study was to improve the soil environment to make it suitable for plant growth by treating chicken manure derived-biochar in soil contaminated with arsenic (As), cadmium (Cd), and lead (Pb). Biochar application increased soil pH and significantly reduced bioavailable As, Cd and Pb, thereby lowering toxicity in plants. Indigenous plant growth also increased by 30.2 and 91.3% in As and Pb contaminated soil under biochar treatment, respectively. Especially, Artemisia japonica Thunb. was effective for phytoextraction due to its accumulation of metals from contaminated soil, along with biochar application. Carex breviculmis R. Br. and Lespedeza cuneata (Dum. Cours.) G. Don. showed decreased above-ground Cd uptake by 57.6 and 44.9%, respectively, and As, Cd and Pb uptake by Juncus decipiens (Buchenau) Nakai decreased by 47.3, 65.7, and 94.1%, respectively, following biochar treatment. Juncus decipiens (Buchenau) Nakai, displayed tolerance in As, Cd and Pb contaminated soils and showed similar growth with or without biochar treatment, while the other three indigenous plant species failed to grow in the absence of biochar treatment. Therefore, J. decipiens is the most suitable candidate for the phytoremediation of metal-contaminated soils, and biochar further promoted plant health and growth.