Plant Physiological Activities Research Articles

Responses of Soil Water Potential and Plant Physiological Status to Pulsed Rainfall Events in Arid Northwestern China: Implications for Disclosing the Water‐Use Strategies of Desert Plants

ABSTRACTSoil water potential (SWP) strongly influences plant productivity and ecosystem functioning, particularly in arid regions characterized by sporadic and pulsed rainfall. This work aims to improve understanding of the response of SWP to varied rainfall pulses, and of the water‐use strategies of a widespread C4 shrub (Haloxylon ammodendron, HA) in arid northwestern China. Rainfall manipulation experiments and field measurements on HA were undertaken to explore the response features of SWP and plant physiological status to pulsed rainfall events of varied magnitudes and durations. The physiological state of HA was evaluated by quantifying critical metrics indicative of plant water‐use strategies, including leaf water potential, photosynthetic rate and transpiration rate. The response value of SWP increased with rainfall magnitude and was most affected by three vital factors (antecedent SWP, total rainfall and rainfall intensity). Low antecedent SWP amplifies SWP's sensitivity to subsequent events, accelerating its response to smaller rainfalls (<5 mm) compared with larger ones (>15 mm). Small rainfall can increase SWP by 0.5–2 MPa in the 20‐cm layer, sustaining plant physiological activities under high antecedent SWP conditions (>−3.5 MPa), with a maximum average rise in photosynthetic rate of 9.20 ± 0.45 μmol CO2 m−2 s−1, enhancing HA's water use efficiency to 1.79 ± 0.22 μmol CO2 mmol−1 H2O. Therefore, small events play a vital role in maintaining SWP and promoting water use of desert plants. Given the nature of plants' utilization of small rainfall events, re‐examining ecologically valid SWP thresholds of HA and other similar desert plants is critical.

Physiological Response of Two Amaranth Varieties (Amaranthus tricolor L.) to Urea Applications

Amaranth, a highly nutritious leaf vegetable, requires adequate nutrients, especially nitrogen fertilizers, to grow well and produce an optimal yield. Urea is commonly used to promote the growth of amaranth plants. This study examined the physiological responses of two varieties of amaranth to the application of urea fertilizer. This study examined the physiological responses of two varieties of amaranth to the application of urea fertilizer. This investigation was conducted in July - August 2023 in Sukosari Village, Jumantono, Karanganyar. The study utilized a completely randomized design (CRD) with two treatment variables. The first variable consisted of a variety of amaranth, including green (B1) and red (B2) varieties. The second variable in the study was the dosages of urea, including 0, 50, 100, 150, 200, 250, and 300 kg.ha-1. The study observed no correlation between various varieties of amaranth and the dose of urea applied in terms of plant growth and physiological activities. There was no discernible impact on the growth or physiological activity of both varieties of amaranth when urea fertilizer was applied. Both varieties of amaranth showed similar physiological responses to urea fertilization. However, the effect of adding urea fertilizer was to enhance the vegetative growth of amaranth plants.

Microneedle electrochemical sensor based on disposable stainless-steel wire for real-time analysis of indole-3-acetic acid and salicylic acid in tomato leaves infected by Pst DC3000 in situ

BackgroundIndole-3-acetic acid (IAA) and salicylic acid (SA), pivotal regulators in plant growth, are integral to a variety of plant physiological activities. The ongoing and simultaneous monitoring of these hormones in vivo enhances our comprehension of their interactive and regulatory roles. Traditional detection methods, such as liquid chromatography-mass spectrometry, cannot obtain precise and immediate information on IAA and SA due to the complexity of sample processing. In contrast, the electrochemical detection method offers high sensitivity, rapid response times, and compactness, making it well-suited for in vivo or real-time detection applications. ResultsA microneedle electrochemical sensor system crafted from disposable stainless steel (SS) wire was specifically designed for the real-time assessment of IAA and SA in plant in situ. This sensor system included a SS wire (100 μm diameter) coated with carbon cement and multi-walled carbon nanotubes, a plain platinum wire (100 μm diameter), and an Ag/AgCl wire (100 μm diameter). Differential pulse voltammetry and amperometry were adopted for detecting SA and IAA within the range of 0.1–20 μM, respectively. This sensor was applied to track IAA and SA fluctuations in tomato leaves during PstDC3000 infection, offering continuous data. Observations indicated an uptick in SA levels following infection, while IAA production was suppressed. The newly developed disposable SS wire-based microneedle electrochemical sensor system is economical, suitable for mass production, and inflicts minimal damage during the monitoring of SA and IAA in plant tissues. SignificanceThis disposable microneedle electrochemical sensor facilitates in vivo detection of IAA and SA in smaller plant tissues and allows for long-time monitoring of their concentrations, which not only propels research into the regulatory and interaction mechanisms of IAA and SA but also furnishes essential tools for advancing precision agriculture.

Dynamic changes of endogenous H2S generation during responding to developmental and environmental signals in Solanum lycopersicum L.

Increasing studies have confirmed the functions of hydrogen sulfide (H2S) as a gas signal molecule (gasotransmitter) in a variety of physiological activities in plants. However, the dynamic changes of endogenous H2S generation, especially the response speed and degree of H2S-generation-associated members, to both developmental and environmental cues in Solanum lycopersicum L. are still poorly understood. Here, we identified and charactered the H2S-generation-associated enzymes in tomato, including O-acetylserine (mercaptan) lyases (OAS-TL), L/D-Cysteine desulfhydrases (L/D-CDes) and nitrogen fixation S (NIFS)-like enzymes, possessing LCD-like activity. Analysis of cis-regulatory elements (CREs) showed that the promoter regions of these H2S-generation-associated genes contained lots of light-, hormone- and stresses-responsive CREs, and transcriptional factors (TFs) binding sites, suggesting that the regulatory mechanism of endogenous H2S generation might involve TFs mediated transcriptional regulation or/and interacting with phytohormones signals. Levels of endogenous H2S exhibited diversity in different organs and developmental stages in tomato, and the top and second highest level of H2S in flowers and ripened fruits hinted the significance of H2S signal in tomato reproduction and fruit development. Furthermore, the expression of SlOAS4, SlLCD, SlDCD2, SlNFS1, and SlNFS2 enhanced continuously during fruit ripening, and the SlOAS4 expression exhibited the most significant up-regulation. The SlDCD enzymatic activity responded more quickly to fruit development cues, while the SlLCD remained at a higher level almost throughout the whole fruit ripening. During environmental stimulus, it was found that the transcriptions of SlDCD2 and SlOAS2 responded faster and stronger to heat stress, while SlOAS4 and SlLCD were activated more quickly and significantly by drought stress. Both SlLCD and SlDCD enzymatic activities could be enhanced by drought and heat stress to varying degrees, and it seemed that the SlLCD was activated to a greater extent and remained at the higher activity for a longer period. With the extension of exogenous phytohormones (ABA, SA, GA, JA, ACC, NAA) treatment, the SlLCD activity and the endogenous H2S content increased in a specific time-dependent manner, and ABA, SA and NAA had more rapid effects on SlLCD activity. By widely explored the dynamic responses of endogenous H2S generation, our study would provide some references for understanding the regulatory mechanism upstream of H2S signaling in tomato growth developments and environmental adaptations.

Genome-wide identification of chalcone synthase (CHS) family members and their expression patterns at the sprouting stage of common bean (Phaseolus vulgaris) under abiotic stress

Secondary metabolites such as flavonoids, produced by plants, could help plants cope with external stress. Flavonoid synthesis is catalyzed by chalcone synthase (CHS). CHS plays a broad role in the growth, development, and physiological activities of plants. However, studies of the CHS gene family in Phaseolus vulgaris are limited. In this study, the HMMER search tool was used to identify 29 CHS members in the reference genome of P. vulgaris. These PvCHS members were divided into 5 subgroups. Notably, subfamilies with close genetic relationships exhibited similarities in motifs and gene structures of PvCHSs. Additionally, analysis of the cis-element indicated the involvement of PvCHSs in response to abiotic stress. Furthermore, quantitative real-time PCR (qRT-PCR) analysis under various abiotic stress conditions revealed that the majority of PvCHSs were associated with the response to salt stress (NaCl), alkaline salt stress (NaHCO3), and heavy metal stress (CdCl2). Particularly, PvCHS01, PvCHS05, PvCHS14, and PvCHS25 were significantly up-regulated under alkaline salt stress. PvCHSs were also correlated with CHS activity and flavonoid content. In addition, exogenous flavonoids were observed to significantly decrease accumulation of ROS in P. vulgaris under alkaline salt stress. This study provides a basis for further analysis of the mechanisms underlying the response of PvCHSs to abiotic stress.

Plant growth promoters boost the photosynthesis related mechanisms and secondary metabolism of late-sown wheat under contrasting saline regimes

There is an imminent risk of higher crop failures owing to weather vagaries for agriculture-based livelihood systems, which are already fragile due to several challenges. The most important challenge is the encounter of crops against multiple environmental stresses under natural field conditions, the combination of these stresses poses complex effects on plant physiological and metabolic activities. To date, the combined effects of salt stress (SS) and late-sown (LS) on physiological and biochemical attributes have not been studied on wheat. A two-year field study was designed to evaluate the effect of plant growth promoters (PGRPs) to alleviate the individual SS, LS and combinations on wheat. The experiment was conducted for three factors, a) late sown and timely sown, b) saline and non-saline conditions and c) PGRPs treatments (thiourea (TU @ 1000 mg L−1), salicylic acid (SA @ 100 mg L−1), hydrogen peroxide (H2O2 @ 100 µM), water spray (H2O) and control). Data revealed that under stress conditions, especially under SS+LS stress plants increased the synthesis of secondary metabolites, enhanced heat dissipation, and showed strict control over the stomatal regulation and gas exchange attributes, all these mechanisms were tweaked to deal with all the stresses. In addition, SS+LS stress followed by SS and LS stress severely reduced the flag leaf area (FLA), chlorophyll pigment contents and chlorophyll fluorescence and carboxylation capacity. However, foliar treatments of PGRPs TU, followed by SA, H2O2, H2O and control improved the chlorophyll fluorescence, pigments contents, gas exchange indicators, and relative water content (RWC). Moreover, PGRPs application improved the FLA, pigment biosynthesis and carboxylation capacity that improved the synthesis of metabolites such as anthocyanin, niacin, flavonoids, phenolics, alkaloids, saponin and riboflavin, which acted as defensive compounds to preserve the photosynthetic capacity irrespective of stress treatments.

Transcription factor PgNAC72 activates DAMMARENEDIOL SYNTHASE expression to promote ginseng saponin biosynthesis.

Ginsenosides, the primary bioactive constituents in ginseng (Panax ginseng), possess substantial pharmacological potential and are in high demand in the market. The plant hormone methyl jasmonate (MeJA) effectively elicits ginsenoside biosynthesis in P. ginseng, though the regulatory mechanism remains largely unexplored. NAC transcription factors are critical in intricate plant regulatory networks and participate in numerous plant physiological activities. In this study, we identified a MeJA-responsive NAC transcription factor gene, PgNAC72, from a transcriptome library produced from MeJA-treated P. ginseng callus. Predominantly expressed in P. ginseng flowers, PgNAC72 localizes to the nucleus. Overexpressing PgNAC72 (OE-PgNAC72) in P. ginseng callus notably elevated total saponin levels, particularly dammarane-type ginsenosides, by upregulating dammarenediol synthase (PgDDS), encoding a key enzyme in the ginsenoside biosynthesis pathway. Electrophoretic mobility shift assays and dual-luciferase assays confirmed that PgNAC72 binds to the NAC-binding elements in the PgDDS promoter, thereby activating its transcription. Further RNA-seq and terpenoid metabolomic data in the OE-PgNAC72 line confirmed that PgNAC72 enhances ginsenoside biosynthesis. These findings uncover a regulatory role of PgNAC72 in MeJA-mediated ginsenoside biosynthesis, providing insights into the ginsenoside regulatory network and presenting a valuable target gene for metabolic engineering.

Removal of Cadmium from Public Smoking area Soil using indoor Plants and Electrical Grounding

Objectives : In this study, the absorption of heavy metals in the soil from smoking areas using indoor plants and electrical grounding was investigated to increase the utility of indoor plants for soil decontamination.Methods : Soil from plant pots in a smoking area was collected for the experimental plant pot preparations. Some of the prepared pots were connected to electrical ground via an electrode. Kidney beans (<i>Phaseolus vulgaris</i>) were seeded, and their growth were observed. After 30 days of the cultivation, TOC (Total Organic Carbon), and metagenomics profiles in the soil was analyzed. To estimate the behavior of the heavy metals in soil and plants, Cadmium concentrations in the samples were analyzed using ICP-MS (Inductively Coupled Plasma-Mass Spectrometry).Results and Discussion : The connection of the electrical ground to the plant pot induced the rapid growth of plant (48.2 ± 2.3% increase in stem growth), compare to the plant in the pot without the electrical ground. TOC analysis showed that the soil from the grounded pots showed the highest value, compared to the control soil (3.08 ± 1.22%), and the soil from the pot without ground connection (2.3 ± 0.1%). The ICP-MS analysis indicated that the plant body in the grounded pot had the highest cadmium concentration at 0.33 ± 0.018 μg/kg. Using the metagenomic analysis, biomineralization related bacterial species (<i>Nocardioides</i> sp., <i>Streptomyces</i> sp., <i>Sphingomonas</i> sp. etc.) were identified from the grounded soil sample. These results suggested that the indoor plant cultivation with the electrical ground connection as an electrical fertilizer enhances the cadmium absorption by plant, exudate secretion from the plant root, and bacterial flora change in the rhizosphere.Conclusion Cadmium in the soil from the smoking area was absorbed by indoor plant with the electrical ground. Therefore, the application of the electrical ground connection (earth) to the electrically insulated outdoor plant pots might enhance the plant growth rate and physiological activity. This application could be a novel soil decontamination method using plants.

Foliar nitrogen uptake in broadleaf evergreen Mediterranean forests: Fertilisation experiment with labelled nitrogen

Atmospheric nitrogen (N) deposition in Mediterranean sclerophyllous forests of Holm oak (Quercus rotundifolia, Q. ilex) in Spain often exceeds empirical critical loads established for ecosystem conservation. There are still uncertainties on the capacity of canopy retention and uptake of the atmospheric N deposited of these forests. Studying and analysing all the forest nitrogen-cycle processes is essential to understand the potential effect of N deposition in these ecosystems. This study conducted a year-long short-term fertilisation experiment with labelled ammonium (15N-NH4) and nitrate (15N-NO3) to estimate foliar N absorption rates and assess the influence of leaf phenology and meteorological seasonal variations. Fertilising solutions were prepared to simulate low and high wet N deposition concentration, based on data reported from previous studies. Additionally, ecophysiological and meteorological measurements were collected to explore potential relationships between absorption rates, plant activity, and weather conditions. The results showed that Holm oak leaves were able to absorb both oxidised and reduced N compounds, with higher rates of NH4+ absorption. N recovery of both NH4+ and NO3− was higher in the low concentration treatments, suggesting reduced effectiveness of absorption as concentration increases. Foliar absorption rates were leaf-age dependent, with the highest values observed in young developing leaves. Foliar uptake showed seasonal changes with a clear reduction during the summer, linked to drought and dry weather conditions, and showing also smaller leaf net assimilation and stomatal conductance. During the rest of the year, foliar N absorption was not clearly associated to plant physiological activity but with environmental conditions. Our findings suggest that Holm oak canopies could absorb an important part of the incoming N deposition, but this process is compound, season and leaf phenology dependent. Further research is therefore needed to better understand and model this part of the N cycle.

Caffeic Acid O-Methyltransferase Gene Family in Mango (Mangifera indica L.) with Transcriptional Analysis under Biotic and Abiotic Stresses and the Role of MiCOMT1 in Salt Tolerance.

Caffeic acid O-methyltransferase (COMT) participates in various physiological activities in plants, such as positive responses to abiotic stresses and the signal transduction of phytohormones. In this study, 18 COMT genes were identified in the chromosome-level reference genome of mango, named MiCOMTs. A phylogenetic tree containing nine groups (I-IX) was constructed based on the amino acid sequences of the 71 COMT proteins from seven species. The phylogenetic tree indicated that the members of the MiCOMTs could be divided into four groups. Quantitative real-time PCR showed that all MiCOMT genes have particularly high expression levels during flowering. The expression levels of MiCOMTs were different under abiotic and biotic stresses, including salt and stimulated drought stresses, ABA and SA treatment, as well as Xanthomonas campestris pv. mangiferaeindicae and Colletotrichum gloeosporioides infection, respectively. Among them, the expression level of MiCOMT1 was significantly up-regulated at 6-72 h after salt and stimulated drought stresses. The results of gene function analysis via the transient overexpression of the MiCOMT1 gene in Nicotiana benthamiana showed that the MiCOMT1 gene can promote the accumulation of ABA and MeJA, and improve the salt tolerance of mango. These results are beneficial to future researchers aiming to understand the biological functions and molecular mechanisms of MiCOMT genes.

Zero-valent iron (nZVI) nanoparticles mediate SlERF1 expression to enhance cadmium stress tolerance in tomato

Cadmium (Cd) pollution threatens plant physiological and biochemical activities and crop production. Significant progress has been made in characterizing how nanoparticles affect Cd stress tolerance; however, the molecular mechanism of nZVI nanoparticles in Cd stress remains largely uncharacterized. Plants treated with nZVI and exposed to Cd had increased antioxidant capacity and reduced Cd accumulation in plant tissues. The nZVI treatment differentially affected the expression of genes involved in plant environmental responses, including those associated with the ERF transcription factor. SlEFR1 was upregulated by Cd stress in nZVI-treated plants when compared with the control and the predicted protein-protein interactions suggested SlERF1 interacts with proteins associated with plant hormone signaling pathway and related to stress. Yeast overexpressing SlEFR1 grew faster after Cd exposure and significantly had higher Cd stress tolerance when compared with empty vector controls. These results suggest that nZVI induces Cd stress tolerance by activating SlERF1 expression to improve plant growth and nutrient accumulation. Our study reveals the molecular mechanism of Cd stress tolerance for improved plant growth and will support new research on overcoming Cd stress and improving vegetable crop production.

Обобщенная модель управления потоками органического углерода и азота на мелиорированных землях

Purpose: to develop a systematic approach to solving the problem of soil fertility based on a model for managing the flows of organic carbon and nitrogen on reclaimed lands. Materials and methods: the working hypothesis of the study is the assumption of the possibility of creating a system of tools for regulating the flows of organic carbon and nitrogen, working within the framework of the principle of nature-likeness and ensuring comprehensive regulation of soil formation factors and increasing the agroecosystem productivity. Results. The conceptual model for managing organic carbon and nitrogen flows on reclaimed lands was developed. The model includes a quantitative calculation of the organic carbon and nitrogen cycles in agroecosystems, the development of scenario forecasts, the development of a control decision and assessment of its execution consequences, the determination of the basic controller’s parameters, the determination of the composition and options for using the controller’s tools, the organization of process monitoring and the assessment of scenario forecasts for actual data. The controller structure of carbon and nitrogen cycle processes for agroecosystems is detailed by the model. The controller includes tools for influencing small nitrogen and carbon cycles, possible ways to implement the tool in a practical application and technologies through which the impact is carried out, with parameters and restrictions specified for a particular case. The basic controller tools are: the plant physiological activity regulation, the phytomass accumulation regulation, the phytomass turnover regulation, the circulation of animal waste regulation, the C:N ratio regulation, the regulation of soil microbiota activity. Conclusions: a conceptual model for managing the flows of organic carbon and nitrogen including a system of tools for the integrated regulation of soil formation factors and increasing the productivity of agroecosystems has been developed.

The unimodal latitudinal pattern of K, Ca and Mg concentration and its potential drivers in forest foliage in eastern China

Potassium (K), calcium (Ca), and magnesium (Mg) are essential elements with important physiological functions in plants. Previous studies showed that leaf K, Ca, and Mg concentrations generally increase with increasing latitudes. However, recent meta-analyses suggested the possibility of a unimodal pattern in the concentrations of these elements along latitudinal gradients. The authenticity of this unimodal latitudinal pattern, however, requires validation through large-scale field experimental data, and exploration of the underlying mechanisms if the pattern is confirmed. Here, we collected leaves of common species of woody plants from 19 montane forests in the north-south transect of eastern China, including 322 species from 160 genera, 67 families; and then determined leaf K, Ca, and Mg concentrations to explore their latitudinal patterns and driving mechanisms. Our results support unimodal latitudinal patterns for all three elements in woody plants across eastern China, with peak values at latitude 36.5 ​± ​1.0° N. The shift of plant-functional-type compositions from evergreen broadleaves to deciduous broadleaves and to conifers along this latitudinal span was the key factor contributing to these patterns. Climatic factors, mainly temperature, and to a lesser extent solar radiation and precipitation, were the main environmental drivers. These factors, by altering the composition of plant communities and regulating plant physiological activities, influence the latitudinal patterns of plant nutrient concentrations. Our findings also suggest that high leaf K, Ca, and Mg concentrations may represent an adaptive strategy for plants to withstand water stress, which might be used to predict plant nutrient responses to climate changes at large scales, and broaden the understanding of biogeochemical cycling of K, Ca, and Mg.

Development of a robust daily soil temperature estimation in semi-arid continental climate using meteorological predictors based on computational intelligent paradigms.

Changes in soil temperature (ST) play an important role in the main mechanisms within the soil, including biological and chemical activities. For instance, they affect the microbial community composition, the speed at which soil organic matter breaks down and becomes minerals. Moreover, the growth and physiological activity of plants are directly influenced by the ST. Additionally, ST indirectly affects plant growth by influencing the accessibility of nutrients in the soil. Therefore, designing an efficient tool for ST estimating at different depths is useful for soil studies by considering meteorological parameters as input parameters, maximal air temperature, minimal air temperature, maximal air relative humidity, minimal air relative humidity, precipitation, and wind speed. This investigation employed various statistical metrics to evaluate the efficacy of the implemented models. These metrics encompassed the correlation coefficient (r), root mean square error (RMSE), Nash-Sutcliffe (NS) efficiency, and mean absolute error (MAE). Hence, this study presented several artificial intelligence-based models, MLPANN, SVR, RFR, and GPR for building robust predictive tools for daily scale ST estimation at 05, 10, 20, 30, 50, and 100cm soil depths. The suggested models are evaluated at two meteorological stations (i.e., Sulaimani and Dukan) located in Kurdistan region, Iraq. Based on assessment of outcomes of this study, the suggested models exhibited exceptional predictive capabilities and comparison of the results showed that among the proposed frameworks, GPR yielded the best results for 05, 10, 20, and 100cm soil depths, with RMSE values of 1.814°C, 1.652°C, 1.773°C, and 2.891°C, respectively. Also, for 50cm soil depth, MLPANN performed the best with an RMSE of 2.289°C at Sulaimani station using the RMSE during the validation phase. Furthermore, GPR produced the most superior outcomes for 10cm, 30cm, and 50cm soil depths, with RMSE values of 1.753°C, 2.270°C, and 2.631°C, respectively. In addition, for 05cm soil depth, SVR achieved the highest level of performance with an RMSE of 1.950°C at Dukan station. The results obtained in this research confirmed that the suggested models have the potential to be effectively used as daily predictive tools at different stations and various depths.

Foliar treatment with melatonin modulates photosynthetic and antioxidant responses in Silybum marianum L. under salt stress

Salinity is a significant global environmental problem that alters the physiology and morphology of plants. Melatonin modulates several physiological activities in plants under various environmental stresses. However, the contribution of melatonin to stress tolerance in response to salinity remains yet unclear. Therefore, the present study was conducted to investigate the potential impact of melatonin on various physiological reactions and metabolic processes in milk thistle (Silybum marianum) exposed to salinity stress. Salinity causes a reduction in photosynthesis and an increase in free radical production, ultimately resulting in growth inhibition. To combat the adverse effects of salinity stress, milk thistle produced increased levels of antioxidant compounds compared with control group. However, this increase in antioxidant activity could not help the plant in tolerating salinity stress. Conversely, foliar treatment of 100 µM melatonin improved photosynthesis (Pn) 64 %, relative water contents RWC (30.8 %), photochemical efficiency 0.44, antioxidant activities, and seedling characteristics in salinity-exposed plants compared with those in the negative control. Moreover, treatment with 100 µM melatonin resulted in better salinity tolerance by enhancing physiological changes such as stomatal conductance, transpiration, CO2 concentration, photosynthesis, germination, and generation of reactive oxygen species and reducing the hydrogen peroxide concentration in milk thistle plants under salinity stress.

Metabolomics combined with physiology and transcriptomics reveal key metabolic pathway responses in apple plants exposure to different selenium concentrations

Selenium (Se) can be absorbed by plants, thereby affects plant physiological activity, interferes gene expression, alters metabolite content and influences plant growth. However, the molecular mechanism underlying the plant response to Se remains unclear. In this study, apple plants were exposed to Se at concentrations of 0, 3, 6, 9, 12, 24, and 48 μM. Low concentrations of Se promoted plant growth, while high Se concentrations (≥24 μM) reduced photosynthesis, disturbed carbon and nitrogen metabolism, damaged the antioxidant system, and ultimately inhibited plant growth. The transcriptome and metabolome revealed that Se mainly affected three pathways, namely the ‘biosynthesis of amino acids’, ‘starch and sucrose metabolism’, and ‘phenylpropanoid biosynthesis’ pathways. 9 μM Se improved the synthesis, catabolism and utilization of amino acids and sugars, ultimately promoted plant growth. However, 24 μM Se up-regulated the related genes expression of PK, GPT, P5CS, SUS, SPS and CYP98A, and accumulated a large number of osmoregulation substances, such as citric acid, L-proline, D-sucrose and chlorogenic acid in the roots, ultimately affected the balance between plant growth and defense. In conclusion, this study reveals new insights into the key metabolic pathway in apple plants responses to Se.

Enhanced removal performance and mechanism of NH4+/NO3− in Starch-FeS-biochar-amended vertical flow constructed wetlands under Pb stress

The co-pollution of nitrogen (N) and lead (Pb) is one of the most serious environmental issues, and the coexistence of Pb increases the difficulty of N removal. Biochar has been proven to be efficient for promoting N removal in constructed wetlands (CWs). However, the knowledge regarding key removal pathways of N and responses of plant physiological activities and microbial community is far insufficient in modified-biochar-added CWs. Therefore, Starch-FeS@PSB biochar (SFSP) was added to vertical flow CWs serving as functional substrate to enhance N removal efficiency under Pb stress, and its mechanism on N and Pb removal was also analyzed. Results showed that adding SFSP to CWs enhanced the nitrification and denitrification intensity of ICW2, and increased removal efficiencies of NO3−-N, NH4+-N and TN by 50.77 %, 35.90 % and 43.71 %, respectively. SFSP cooperated with anammox bacteria and denitrifying bacteria enhanced the removal of N under Pb stress. Furthermore, SFSP alleviated Pb stress on Iris pseudacorus L. and increased the relative abundance of Thiobacillus, Candidatus Kuenenia, Sulfurimonas and Geobacter so as to promote microbial N removal. Therefore, SFSP can be used as an efficient and eco-friendly functional substrate in CWs to remediate N and Pb co-polluted wastewater.

Zinc oxide nanoparticles: A unique saline stress mitigator with the potential to increase future crop production

Globally, soil salinity is an abiotic stress that can threaten arable lands and crop production and consequently can negatively affect food security. Therefore, the aim of this review was to study the utilizing zinc oxide nanoparticles (ZnO-NPs) as a novel approach to mitigate salinity stress and its negative impacts on environment and crop productivity. The application of ZnO-NPs can significantly enhance plant growth, physiological and metabolic activity, and yield as well as crop quality. The antioxidant enzymes activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) are increased when ZnO-NPs are applied which can mitigate the damage caused by ROS species and make them a valuable tool for future agriculture. The sucrose synthesis which ultimately biosynthesizes lipopolysaccharides (LP), glycinebetaine (GB), and total soluble protein (TSP), and enhanced ribulose bisphosphate carboxylase-oxygenase activity, light-capturing efficiency of photosystem II, as well as the ability to transport electrons under salinity stress are increased by the application of ZnO-NPs. Therefore, ZnO-NPs can be used as a potential strategy for promoting precision agriculture. The existing yield gap under a saline environment can be minimized by promoting the application of ZnO-NPs as it serves as a cheap, environment-friendly, and efficient source of Zn. In a nutshell, being an efficient and eco-friendly nanomaterial ZnO-NPs play a key role in mitigating saline stress by alleviating NaCl toxicity and enhancing crop productivity in saline soils.

Incorporating cropping systems with eco-friendly strategies and solutions to mitigate the effects of climate change on crop production

Agricultural practices account for approximately 13.5% of all human greenhouse gas emissions and are a significant driver of land-use change. As a result, natural soil fertility has been dramatically reduced, impacting agricultural productivity, the environment, and human health. New technologies, such as green technologies, can address these challenges by adjusting agricultural practices. This paper reviews recent research on climate-mitigating agricultural practices in agronomic cropping systems, and to show how they affect crops, pests, and beneficial arthropods. An optimal amount of synthetic fertilizers and agrochemicals are necessary to maintain production costs, while maximizing outputs. There is a need to develop intelligent, responsive, biodegradable, and biocompatible materials to manufacture green, safe, and efficient fertilizers and pesticides. Site-specific nutrient management (SSNM), is an efficient strategy for managing nutrient efficiency. This system employs inorganic and organic supplies, geographical and temporal soil heterogeneity, crop demands of nutrients, and cropping techniques. A practical strategy to exploit the response of plants to abiotic factors, including the duration, extent, and incidence of specific tolerance mechanisms, is to deploy plant-based products (PBPs). Using microbials (MPBs) is a sustainable strategy to promote plant growth and productivity, even under abiotic situations. Further, nanoparticles, such as iron, silicon, silver, and titanium, can boost plant growth and physiological activity in wheat, maize, soybeans, and spinach are excellent alternatives to artificial chemical pesticides, as they are biodegradable and only affect the target species.Pest and predator responses to agricultural techniques require immediate intervention to mitigate against climate change and ensure food security.

Silicon Induces Heat and Salinity Tolerance in Wheat by Increasing Antioxidant Activities, Photosynthetic Activity, Nutrient Homeostasis, and Osmo-Protectant Synthesis.

Modern agriculture is facing the challenges of salinity and heat stresses, which pose a serious threat to crop productivity and global food security. Thus, it is necessary to develop the appropriate measures to minimize the impacts of these serious stresses on field crops. Silicon (Si) is the second most abundant element on earth and has been recognized as an important substance to mitigate the adverse effects of abiotic stresses. Thus, the present study determined the role of Si in mitigating adverse impacts of salinity stress (SS) and heat stress (HS) on wheat crop. This study examined response of different wheat genotypes, namely Akbar-2019, Subhani-2021, and Faisalabad-2008, under different treatments: control, SS (8 dSm-1), HS, SS + HS, control + Si, SS + Si, HS+ Si, and SS + HS+ Si. This study's findings reveal that HS and SS caused a significant decrease in the growth and yield of wheat by increasing electrolyte leakage (EL), malondialdehyde (MDA), and hydrogen peroxide (H2O2) production; sodium (Na+) and chloride (Cl-) accumulation; and decreasing relative water content (RWC), chlorophyll and carotenoid content, total soluble proteins (TSP), and free amino acids (FAA), as well as nutrient uptake (potassium, K; calcium, Ca; and magnesium, Mg). However, Si application offsets the negative effects of both salinity and HS and improved the growth and yield of wheat by increasing chlorophyll and carotenoid contents, RWC, antioxidant activity, TSP, FAA accumulation, and nutrient uptake (Ca, K, and Mg); decreasing EL, electrolyte leakage, MDA, and H2O2; and restricting the uptake of Na+ and Cl-. Thus, the application of Si could be an important approach to improve wheat growth and yield under normal and combined saline and HS conditions by improving plant physiological functioning, antioxidant activities, nutrient homeostasis, and osmolyte accumulation.