Search Results (204)

Reducing the greenhouse gas (GHG) intensity of dairy production remains challenging because enteric methane and upstream supply chain emissions persist despite existing mitigation strategies. This study evaluated a supply chain decarbonization approach in which Spirulina (Arthospira platensis) produced through a carbon-removal supply chain (GeoSpirulina) was incorporated into dairy rations to enable net supply chain carbon removal within cradle-to-farm-gate boundaries. A carbon-focused life cycle assessment (LCA) was combined with a commercial-scale feeding trial to determine an appropriate inclusion rate and assess production outcomes. The LCA integrated primary activity and production data from the commercial dairy farm with previously published GeoSpirulina production and soil organic carbon sequestration data derived from primary Icelandic production and field studies, supplemented by secondary background datasets and published dairy emission estimates. GeoSpirulina was produced using geothermal energy and coupled with soil organic carbon sequestration associated with the application of residual biomass as a soil biostimulant, resulting in a modeled net-negative production footprint. Under the defined LCA assumptions, supplementation with 2 g cow⁻¹ day⁻¹ of GeoSpirulina reduced the modeled milk GHG intensity from approximately 1.9 to 0.06 kg CO₂e kg⁻¹ at the farm gate. Scenario analysis identified active vitamin B₁₂ concentration as a key driver of the modeled carbon balance. Milk yield and group-level feed efficiency were unaffected, whereas butterfat (+4.7%, p = 0.002), fatty acids (+4.4%, p = 0.011), and somatic cell count (−71%, p = 0.007) improved without detectable adverse effects. These findings suggest that carbon-negative feed ingredients may provide a complementary sustainability strategy for dairy production by embedding measurable carbon removal within agricultural supply chains while maintaining production performance. Although this approach counterbalances rather than eliminates biological emissions, it may contribute to broader dairy decarbonization and sustainable food-production strategies alongside direct greenhouse gas mitigation interventions. Full article

Multiomics is increasingly valued as a strategy for investigating the regulatory mechanisms by which plants respond to adverse stress conditions. Currently, information on the molecular processes underlying plant responses to Pb stress, particularly those observed through an approach that combines proteomics and metabolomics, is lacking. Therefore, in this study, we aimed to explore functional correlations between Pb-responsive proteins and metabolites under Pb stress by performing label-free quantitative proteomics and untargeted metabolomics on the roots of the Pb hyperaccumulator Pogonatherum crinitum (Thunb.) Kunth. The selected Pb stress-responsive proteins were functionally verified using quantitative reverse transcription polymerase chain reaction (RT-qPCR) and parallel reaction monitoring (PRM). Under Pb stress, 397 upregulated and 431 downregulated proteins were identified through proteomic analysis. Metabolomic analysis identified 478 upregulated and 354 downregulated metabolites. Pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes revealed that differentially expressed proteins and metabolites were involved in pathways linked to heavy metal stress, such as starch and sucrose metabolism and plant hormone signal transduction. Through integrated proteomic and metabolomics analyses, we uncovered the coordinated regulatory interplay between glutathione (GSH) metabolism and jasmonic acid signaling. GSH reductase and 12-oxophytodienoate reductase drive the accumulation of GSH and jasmonic acid, respectively. The synergistic enhancement of these components is critical for maintaining cellular redox homeostasis and activating hormone-mediated defense signaling. These downstream metabolites were upregulated under Pb stress. RT-qPCR validation revealed that the transcriptional change trends were consistent with those of the proteomics analysis. Further quantitative validation of the target protein using PRM revealed significant upregulation under Pb stress. In conclusion, the P. crinitum root system upregulated the activity of key enzymes in the antioxidant system and plant hormone synthesis under Pb stress, thereby regulating the accumulation of GSH, glutamate, and metabolites for jasmonic acid synthesis. This integrated regulatory network provides promising candidate targets for breeding Pb-tolerant hyperaccumulators to remediate Pb-contaminated farmland and mining soil. Full article

The durability of concrete in chemically aggressive environments remains a major concern for marine structures, wastewater systems, industrial facilities, pavements, and foundations exposed to sulfate-bearing soils. Geopolymer concrete has attracted increasing attention as a lower-carbon alternative to ordinary Portland cement concrete because its aluminosilicate-rich reaction products, reduced portlandite content, and adjustable precursor–activator chemistry may enhance resistance to various chemical attack mechanisms. However, its durability is strongly governed by mixture composition and exposure regime, and therefore cannot be generalized across all geopolymer systems. This review provides a systematic and critical synthesis of the chemical attack resistance of geopolymer concrete, focusing on acid, sulfate, chloride, marine, wastewater, and combined aggressive exposures. The effects of precursor chemistry, calcium content, activator composition, curing regime, additives, fibers, aggregate type, recycled materials, and environmental coupling are examined in relation to degradation mechanisms and durability indicators. A PRISMA-informed methodology was used to identify, screen, verify, and synthesize primary experimental and modeling studies. The reviewed evidence indicates that low-calcium and well-polymerized geopolymer systems often exhibit favorable sulfate resistance due to the reduced availability of calcium-bearing phases that form expansive products, whereas chloride resistance is primarily governed by pore refinement, chloride transport, binding capacity, pore–solution alkalinity, and reinforcement corrosion behavior. In contrast, acid resistance remains more variable, depending on acid type, pH, exposure duration, solution renewal, calcium content, and the stability of protective silica-rich layers. Additives and alternative aggregates can enhance durability by refining the pore structure, improving the interfacial transition zone, or controlling cracking, but excessive or incompatible dosages may have adverse effects. Overall, geopolymer concrete offers strong potential for chemically aggressive infrastructure when designed through performance-based criteria and validated under realistic multi-exposure conditions. Full article

Organic matter critically restricts the effectiveness of conventional cement stabilization of soft soils and undermines the performance of reinforced soil layers. However, how different organic matter components affect reactive MgO carbonation reinforcement remains poorly understood. This study adopted Portland cement (PC) stabilization, MgO stabilization and MgO carbonation to treat silty clay with 0~8% fulvic acid (FA) and humic acid (HA). The engineering performance and microstructural features of stabilized soils were investigated via dry density, unconfined compressive strength (UCS) and pH tests, combined with X-ray diffraction (XRD), scanning electron microscopy (SEM) and pore structure analysis. The results show that MgO carbonation achieved the optimal densification effect, delivering distinctly higher dry density and UCS than the other two methods. Increased organic matter content reduced soil alkalinity and hindered strength development, with FA exerting a stronger inhibitory impact than HA due to lower UCS and higher dosage sensitivity. Carbonation effectively mitigated the adverse effects of FA and HA and yielded superior soil strength. XRD identified nesquehonite, dypingite and hydromagnesite as dominant carbonation products; organic matter reduced the formation of these strength-enhancing phases and retained uncarbonated brucite. SEM further verified that organic matter modified carbonate morphology and distribution, forming loose microstructures despite reduced pore volume. Overall, reactive MgO carbonation presents stronger anti-interference capability against organic matter than conventional PC stabilization. It improves the performance of organic-rich soft soils and realizes CO₂ sequestration. This study provides experimental support and practical insights for the engineering application of low-carbon MgO-CO₂ soil stabilization technology. Full article

Malaysia plans to produce 80% of its rice requirement by 2030. To achieve the plan, new agronomic approaches have to be put in place to enhance the fertility of rice soils in the country. One of the options is to turn the infertile acid sulfate soils endemic in the low-lying coastal plains of Peninsular Malaysia into a new granary area. Using traditional agro-techs, rice yield in the area is below the national average of 4 t/ha/season. The low yield is due to soil acidity stress (pH < 4) together with Al³⁺ and/or Fe²⁺ toxicity. The critical pH for rice is 6, while the respective critical Al³⁺ and Fe²⁺ concentrations are 5.2 µM and 14.6 µM. The adverse conditions contributing to yield reduction can be resolved by applying appropriate soil amendments known to raise water pH, eliminating the toxic cations. The recommended agronomic practice is to apply ground magnesium limestone (GML) or ground basalt, or better still, apply GML or ground basalt in combination with bio-fertilizer, fortified with phosphate-solubilizing bacteria (PSB). The PSB increases water pH as well as helps rice plants secrete organic acids that reduce the toxic effects of Al³⁺ and Fe²⁺ via chelation. When pH rises >5, the toxic metals are precipitated, forming inert hydroxides. Ultimately, rice yield can be increased from 3 to 5 t/ha/season, which can last more than three consecutive cropping seasons. If this agro-tech is adopted throughout ASEAN, food security in the region will be sustained. Full article

Soil contamination with metals is a significant environmental problem that can adversely affect the growth of crops and the quality of yields. Among potentially toxic elements, iron plays a particularly important role, as excessive amounts of it disrupt physiological processes and plant nutrition. The aim of the study was to assess the impact of varying levels of iron contamination in the soil and the effectiveness of selected neutralising substances in mitigating iron stress on the growth, mass, SPAD index and chemical composition of maize biomass. In the absence of additives, excessive iron content (750 mg Fe kg⁻¹ of soil) significantly restricted plant growth, causing a 62% reduction in plant height and a reduction in fresh and dry matter mass of 92% and 94%, respectively, compared to the control. However, the lowest dose of iron (250 mg Fe kg⁻¹ of soil) in without additions series exhibited a stimulating effect, resulting in an increase in maize height and fresh matter mass. Among the tested neutralising substances, bentonite proved to be the most effective, significantly mitigating the negative effects of iron by increasing plant height by average 92% and fresh and dry matter mass by 167% and 193%, respectively, compared to the series without additives. Bentonite and humic acids also limited the decline in the SPAD index during subsequent growth stages. Soil contamination with iron significantly altered the chemical composition of maize biomass, with the additives used correcting these changes to varying degrees. Full article

Rice seedlings are typically grown in high-phosphorus nursery soils in practice, which reduces rice root growth and the plant’s ability to adapt to adverse conditions after transplantation to the paddy field. Thus, it is important to improve rice root development in high-phosphorus nursery soils. Rice root developments are closely connected with soil microorganisms. Arbuscular mycorrhizal fungi (AMF) can promote rice root growth and help improve rice performance in resisting adverse conditions. To illustrate the mechanisms of rice seedlings with AMF inoculation under suitable and high-phosphorus nursery soils in resisting adverse conditions, rice seedlings were cultivated in suitable and high-phosphorus nursery soils inoculated with AMF JD5 (Paraglomus sp.) and transplanted into soda saline–alkaline soils following successful AMF inoculation. Results showed that under high-phosphorus conditions, AMF JD5 inoculation significantly promoted plant height and root elongation, likely through increased total chlorophyll content. Concurrently, proline content was reduced, whereas soluble sugar and soluble protein contents were elevated, indicating alleviation of osmotic stress induced by saline–alkaline conditions. Moreover, AMF JD5-inoculated seedlings exhibited increased CAT activity, which efficiently scavenged reactive oxygen species (ROS) generated under salt–alkaline stress and reduced lipid peroxidation. However, thiobarbituric acid reactive substances (TBARS) content was significantly decreased with AMF inoculation in high-phosphorus conditions. Collectively, these findings suggest that AMF JD5 inoculation in high-phosphorus nursery soils establishes a physiological and biochemical foundation that maintains rice resilience against saline–alkaline stress throughout early growth. Full article

With the rapid progression of global industrialization and urbanization, heavy metal contamination has emerged as a major global threat, especially cadmium pollution. Consequently, optimizing remediation measures has become a pivotal means to solve cadmium contamination. Compared to traditional physical and chemical remediation methods, microbial remediation has great potential in addressing cadmium pollution. In this study, a novel bacterial strain, Chryseobacterium sp. HGX-24, exhibiting high cadmium resistance was successfully isolated and screened from cadmium-contaminated environments. A preliminary discussion of the response mechanisms of this strain under cadmium stress is provided. Additionally, preliminarily explored the synergistic remediation of microbial-plant in cadmium-contaminated soil. Under conditions of high cadmium concentration, cadmium ions were effectively adsorbed by strain HGX-24 through extracellular polymers and functional groups on the cell wall surface, including −COOH, −CONH−, −NH, −OH, and >C=O. Extracellular proteins and polysaccharides were secreted by strain HGX-24 to regulate the adverse effects of heavy-metal cadmium ions on bacterial growth. Furthermore, the expression of genes such as antioxidant defense and ROS scavenging (katG, fabG, ybjT), Fe-S cluster assembly (sufB, sufD), sulfur metabolism (cysAU), amino acid metabolism (hisA, cysD, aspC), phenylacetic acid catabolism (paaC), and ribosomal proteins (rplC, rpsC, rpsL, rplA, rplY, rpmC) was regulated, affecting the synthesis and metabolism of membrane transporters (ABC transporters and efflux RND transporters), antioxidant enzymes (SOD, COT, POD), Fe-S clusters, thioredoxin family proteins, and ribosomal proteins, thereby enhancing resistance to cadmium toxicity. Moreover, strain HGX-24 was found to regulate the activities of redox enzymes in Zea mays L., thereby alleviating oxidative stress and reducing the negative feedback effects of reactive oxygen species in Z. mays. Full article

Excessive fertilizer application is a common practice in agricultural production in the North China Plain. To determine an optimal fertilization strategy for summer maize with nitrogen-fixing bacterial inoculation, we conducted a two-year field experiment (2022–2023) using the conventional fertilization rate (600 kg ha⁻¹ NPK; N:P₂O₅:K₂O = 28:8:10; 100F by default) as a control and examined the effects of fertilizer reduction (at 90%, 80%, 62.5%, and 50% of 100F) combined with Azotobacter chroococcum inoculation on maize plants and soil. Although fertilizer reduction increased free amino acid content, soluble sugars, proteins, and fatty acids contents were reduced. However, bacterial inoculation significantly enhanced all the above nutritional indices in maize leaves. Bacterial inoculation under fertilizer reduction conditions can enhance the activity of key nitrogen metabolism enzymes (i.e., GS and GOGAT), which further supports nitrogen, sugar, and lipid metabolism in maize plants. Additionally, bacterial inoculation promoted root development, biomass accumulation, and grain nutritional value while significantly increasing yield under reduced fertilizer conditions. The highest yield (11,454 kg ha⁻¹) was achieved with bacterial inoculation at approximately 87F (≈522 kg ha⁻¹ NPK), while the non-inoculated control reached a peak yield (11,032 kg ha⁻¹) only at around 90.5F (≈543 kg ha⁻¹). The complementary effects of bacterial inoculation with fertilizer reduction resulted in improved nutrient supply and modulation of soil microbial diversity. Inoculation of A. chroococcum increased soil ammonium and nitrate levels and decreased soil pH, though it was associated with a decline in overall bacterial richness, which may have persistent and adverse effects on the soil. Both fertilizer reduction and bacterial inoculation significantly altered microbial community structure, with notable interannual variation. Collectively, our findings suggest that moderate fertilizer reduction (9.5–13%) combined with nitrogen-fixing bacteria inoculation can support sustainable maize production by maintaining higher yield, enhancing nutrient use efficiency, and improving soil health. However, due to pH-lowering effects, long-term monitoring is necessary to assess the ecological impact of nitrogen-fixing bacteria inoculation on soil microbial balance. Full article

Glycogen synthase kinase 3 (GSK3/SHAGGY-like kinase) plays a pivotal role in regulating plant growth, development, and stress responses. To elucidate the characteristics of the GSK family in Glycine max, this study employed whole-genome data combined with bioinformatic and gene expression analyses to investigate the gene structure, chromosomal localization, collinearity, phylogenetic evolution, promoter cis-elements and differential gene expression analysis. Additionally, the expression patterns of GmGSK genes under manganese (Mn) stress and their associated phenotypic alterations were analyzed. A total of 22 GmGSK family members were identified, all harboring the characteristic GSK kinase domain. These members are distributed across 16 chromosomes, encoding proteins ranging from 380 to 802 amino acids (aa) in length. Phylogenetic analysis classified the GmGSK family into four evolutionary clades, consistent with patterns observed in Arabidopsis and Oryza sativa. Members within the same clade share identical exon-intron structures and conserved motifs. Collinearity analysis revealed that segmental duplication events have been crucial in the functional expansion of the GmGSK family through intraspecific collinearity. In recent years, alongside industrial development and fertilizer imbalance, the effective manganese concentration in agricultural soils has risen abnormally in some regions of China, leading to toxic effects on crops. Soybean, an oilseed crop relatively sensitive to manganese, has been adversely impacted. Clarifying the response mechanisms of soybean seedlings to manganese stress is therefore of significant importance for improving both yield and quality. Manganese stress treatment induced significant up-/down-regulation of specific GmGSK members in soybean, concomitant with pronounced inhibition of root elongation and leaf growth. This study provides a theoretical framework for deciphering the molecular regulatory mechanisms by which the GmGSK gene family mediates plant responses to Mn stress, offers insights into soybean Mn tolerance mechanisms, and establishes a foundation for genetic improvement of Mn-tolerant traits in crops. Full article

Aluminum (Al) toxicity is a major constraint on crop growth and productivity in acidic soils, affecting root development, nutrient uptake, and photosynthetic performance. The use of Si is a promising strategy to overcome the adverse effects of Al toxicity on species of agronomic interest. Between 2020 and 2026, 15 studies across nine species consistently demonstrated that silicon mitigated aluminum toxicity, regardless of their classification as silicon accumulators. In plants, Si mitigates Al toxicity through a combination of physical, chemical, and biochemical mechanisms that operate simultaneously. In the rhizosphere, Si interacts directly with Al³⁺ ions, favoring the formation of hydroxyaluminosilicates (HASs), which reduces the bioavailable fraction of Al. Evidence indicates that solution pH is a critical factor governing HAS formation, with minimal attenuation of Al toxicity observed at pH values below 4.5. Within the plant, Si modulates the antioxidant defense system by enhancing the activity of enzymes such as catalase, peroxidase, and ascorbate peroxidase, thereby reducing oxidative stress typically triggered by Al toxicity. Moreover, Si influences the biosynthesis of lignin and phenolic compounds with Al-chelating capacity, contributing to detoxification at the cellular level. In soybean and rice, Si supply substantially reduced Al deposition in the root apical cell wall, with decreases of approximately 52% and 41.3%, respectively. This reduction was consistently associated with improved root elongation, maintenance of root structural integrity, mitigation of cellular deformation, and preservation of root thickness and vascular organization. Although these mechanisms have been described, a comprehensive synthesis of studies published from 2020 to 2026 has been lacking, particularly regarding the integration of in-plant processes and species-specific responses. This review fills this gap by critically examining recent findings, highlighting the multifaceted role of Si in alleviating Al stress, and discussing implications for agronomic applications in acidic soils. Collectively, the evidence underscores Si as an effective tool to enhance plant tolerance to Al; however, most available evidence is derived from early plant developmental stages and hydroponic or highly controlled systems, which limits the direct extrapolation of these findings to soil and field conditions. Future advances will require studies under soil environments, accounting for species-specific responses, soil properties, management systems, and plant developmental stages. Full article

Polycyclic aromatic hydrocarbons (PAHs) are widely prevalent harmful organic pollutants. Enzymatic activities (such as those of dehydrogenases, catalase, protease and urease), as well as the microbial community structure and assembly (through 16S and ITS amplicon sequencing), were evaluated 90 days after PAH contamination and compared to those in normal soils. Microbial activity, as indicated by soil urease, catalase, and protease activities, was inhibited under PAH stress. Furthermore, PAH stress exerted significant impacts on the soil microbial community structure. Notably, PAH stress reduced soil bacterial and fungal biomass and inhibited the abundance of microbial taxa involved in soil carbon and nitrogen cycling (e.g., Marmoricola, Pedobacter, and Streptomyces), along with the majority of predicted responsive metabolic functions, particularly those related to amino acid and carbohydrate metabolism. PAH stress enriched PAH-degrading microorganisms, including Pseudomonas, Mycobacterium, Bacillus, Cycloclasticus, and Flavobacterium. The niche breadth of bacterial and fungal communities decreased significantly under PAH stress (51.5 and 14.1, respectively) compared to that in normal soil (63.7 and 22.3), which was further supported by Beta Nearest Taxon Index and co-occurrence network analysis. PAH stress increased the contribution of heterogeneous selection to soil microbial assembly (100%) compared to that in normal soil (80%). Thus, the majority of microbial community responses to PAH stress were adversely affected. These results suggest that PAH contamination may profoundly affect the soil quality by restricting the survival space of bacteria and fungi. Full article

Soil salinity poses a major threat to agriculture by severely limiting how well plants grow and produce crops. It strongly inhibits seed germination, a critical stage for plant life. Thus, it is critical to understand the complex ways salinity affects seed germination at the physiological, biochemical, and molecular levels to develop effective salt stress mitigation strategies. This review synthesizes the underlying mechanisms of how salinity inhibits seed germination, the observed impacts of this inhibition, and potential mitigation strategies. The review revealed that high salt concentrations reduce seed germination percentage and increase germination time through multiple mechanisms. They create osmotic stress that reduces water uptake, cause ion toxicity that disrupts critical metabolic activities, and induce oxidative stress. Furthermore, salinity can modify endogenous hormonal profiles, specifically by decreasing germination stimulants like gibberellic acids while increasing inhibitors like abscisic acid. The review finally explored the strategies to mitigate salinity’s adverse effects on seed germination. They include seed priming, a technique involving partial hydration of seeds in an eliciting solution, a promising biotechnological tool to overcome salinity problems during seed germination. Other approaches are the use of organic amendments and the breeding of salt-tolerant varieties. Future research should combine conventional and advanced molecular technologies to develop salt-tolerant cultivars to ensure food security in salt-affected agricultural lands. Full article

Root pruning affects the ability of roots of Quercus variabilis Blume to absorb water and nutrients. Suillus grevillea can form a mutualistic symbiosis with Quercus variabilis Blume. A pot experiment in three compartments with two inoculation treatments (inoculation with Suillus grevillea and noninoculation control) and four different root pruning treatments (0, 1/4, 1/3, and 1/2 of the main root length pruned) was conducted. The shoot dry weight, root dry weight, shoot and root N, P and K contents, root morphological and physiological parameters of Quercus variabilis Blume seedlings, and soil properties were measured. The results showed that root pruning affected root endogenous hormone levels, root morphology, shoot and root nutrient absorption, and biomass accumulation. Compared with those without inoculation, the shoot dry weight, root dry weights, shoot and root N, and P and K contents of inoculated plants were greater, regardless of the degree of root pruning. The root length, root projection area, root surface area, root average diameter, root density, root volume, and root tip number increased in response to Suillus grevillea. The root auxin (IAA), cytokinin (CTK), gibberellin (GA), zeatin riboside (ZR), and salicylic acid (SA) contents were greater in inoculated Quercus variabilis Blume seedlings than in noninoculated plants. Inoculation with Suillus grevillea improved the soil microenvironment around the seedlings. Suillus grevillea can compensate for the adverse effects of root pruning on nutrient absorption, root morphological and physiological growth and the soil properties of Quercus variabilis Blume seedlings. Full article

Agriculture in semi-arid regions faces challenges, such as water scarcity and low soil fertility, making the forage cactus a highly important crop due to its crassulacean acid metabolism (CAM) pathway. The productivity of the forage cactus, however, depends on proper water and nutrient management, especially nitrogen. Despite its importance, there is little research into the effects of nitrogen fertilisation on productive, photochemical, physiological and biochemical parameters, or on intercropping systems. Increasing doses of nitrogen are assumed to enhance CAM pathway, improving productivity, gas exchange, photochemical efficiency and antioxidant accumulation, in addition to mitigating the effects of oxidative stress under adverse conditions. The experiment was conducted in Serra Talhada, Pernambuco, Brazil, in a randomised block design with four replications. Changes in the biometric, productive, photochemical, physiological and biochemical parameters were evaluated in forage cactus intercropped with sorghum (Sorghum bicolor) or pigeon pea (Cajanus cajan) subjected to different doses of nitrogen (0, 75, 150, 300 and 450 kg ha⁻¹). The results showed that nitrogen fertilisation promoted a higher photosynthetic rate and greater stomatal conductance, increased transpiration, and higher levels of pigment and soluble proteins, in addition to reducing lipid peroxidation. Our findings revealed that the cactus—pigeon pea intercropping system has better photosynthetic, enzymatic and productive performance at a dose of 150 kg N ha⁻¹, whereas the cactus—sorghum intercropping system required 450 kg N ha⁻¹ to achieve similar results. Overall, proper nitrogen management in intercropping systems can optimise the physiological performance and productivity of the forage cactus in semi-arid environments. Full article