Search Results (2,219)

A diverse array of soil microorganisms exhibit plant growth-promoting (PGP) traits, many of which enhance root growth and development. These microorganisms include various taxa of bacteria, fungi, microalgae and yeasts—some of which are currently used in biofertilizers and biostimulant formulations. Recent studies have begun to unravel the complex communication between plant roots and beneficial microorganisms, revealing mechanisms that modulate root nitrogen (N) uptake beyond atmospheric N₂ fixation pathways. Root N uptake is tightly regulated by plants through multiple mechanisms. These include transcriptional and post-transcriptional control of plasma membrane-localized N transporters in the epidermis, endodermis, and xylem parenchyma. Additionally, N uptake efficiency is influenced by vacuolar N storage, assimilation of inorganic N into organic compounds, and the maintenance of electrochemical gradients across root cell membranes. Many of these processes are modulated by microbial signals. This review synthesizes current knowledge on how soil microorganisms influence root N uptake, with a focus on signaling molecules released by soil beneficial microbes. These signals include phytohormones, volatile organic compounds (VOCs), and various low-molecular-weight organic compounds that affect transporter expression, root architecture, and cellular homeostasis. Special attention is paid to the molecular and physiological pathways through which these microbial signals enhance plant N acquisition and overall nutrient use efficiency. Full article

This study compared the effects of two C3 forages (Italian ryegrass [RG], Timothy grass [TG]) and two C4 forages (Klein grass [KG], Bermuda grass [BG]) on growth performance, nutrient digestibility, and nitrogen (N) balance in Korean crossbred black goats to evaluate C4 warm-season forages as alternatives under changing climate conditions. Sixteen castrated goats (10 months old) were allocated to four treatments using a randomized complete block design. Diets contained 40% treatment-specific forage and 60% commercial concentrate. After adaptation periods, a 5-day metabolism trial measured performance and digestibility parameters. No significant differences occurred among treatments for growth performance or digestibility of dry matter, crude protein, neutral detergent fiber, ash, and non-fiber carbohydrate. C4 grasses showed significantly lower acid detergent fiber and ether extract digestibility than C3 grasses, with KG having the lowest ether extract digestibility. The KG group had higher N intake and absorption than the TG group, while BG showed lower urinary and total N excretion than KG. No differences existed in retained N, utilization efficiency, or biological value among groups. Both C3 and C4 forages supported comparable goat growth performance, providing a reference for utilizing different photosynthetic pathway forages under changing climatic conditions. Full article

Micro-sprinkling fertigation, a novel irrigation and fertilization way, can improve the grain yield (GY) and nitrogen use efficiency (NUE) of winter wheat to meet sustainable agriculture requirements. In order to clarify the physiological basis behind the improvements, a field experiment with a split-plot design was conducted during the 2020–2021 and 2021–2022 growing seasons. The main plot encompassed two irrigation and fertilization modes, namely, conventional irrigation and fertilization (CIF) and micro-sprinkling fertigation (MSF), and the subplots included four nitrogen application rates (0, 120, 180, and 240 kg ha⁻¹, denoted as N0, N120, N180, and N240, respectively). Moreover, a ¹⁵N isotopic tracer experiment was performed to determine the distributions of nitrogen in the soil. Compared with those under CIF, the GY under MSF at N180 and N240 significantly increased by 9.09% and 9.72%, which was driven mainly by increases in the grain number (GN) and thousand-grain weight (TGW). The increase in the TGW under MSF was the result of the significantly increased net photosynthesis rate at the grain-filling stage. Notably, the number and dry weight of inefficient tillers and the number of ears with fewer than 10 grains were significantly lower under MSF than those under CIF. In addition, the ¹⁵N isotopic tracer experiment revealed that nitrogen was primarily concentrated in the 0–30 cm soil layers under MSF, which conforms well with the spatial distributions of the roots and water, and subsequently improved the NUE under N180 and N240. In conclusion, MSF enhanced both the GY and NUE at the N180 level by optimizing root–water–nitrogen spatiotemporal coordination and reducing redundant tillering. Full article

The aim of this study was to evaluate the treatment efficiency and applicability of using textile-based mats as roof biofilters on urban buildings for purifying preliminary treated wastewater (PTW) collected from a three-chamber septic tank. Therefore, a pilot plant with a 15° pitched wooden roof and two tracks for laying two mats made of different materials—polypropylene (PP), designated as Mat 1, and polyethylene terephthalate (PET), designated as Mat 2—was constructed at ground level under outdoor conditions. The plant was operated in parallel for a period of 455 days. Significant differences (p < 0.05) were observed in the results of the mass removal efficiencies between the two mats, with Mat 1 achieving mean removals of five-day biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), ammonium-nitrogen (NH₄-N), and total nitrogen (TN) of 85%, 73%, 75%, and 38%, respectively, and Mat 2 achieving comparatively higher removals of 97%, 84%, 90%, and 57%, respectively. The mean concentrations of BOD₅ and COD at the outflow of both mats met the minimum water quality requirements for discharge and successfully met the minimum water quality class B for agricultural reuse. However, the comparatively low mean E. coli removal efficiencies of 2.0 and 2.4 log-units in Mat 1 and Mat 2, respectively, demonstrate the need for an effluent disinfection system. Highly efficient mass removal efficiencies were observed in the presence of dense vegetation on the mats, which may lead to a potential improvement in the urban climate through high daily evapotranspiration. Overall, this study demonstrates the potential for using lightweight, textile-based mats on rooftops to efficiently treat PTW from urban buildings, offering a promising decentralized wastewater management approach for climate-resilient cities. Full article

Real-time nitrogen (N) management based on the leaf color chart (LCC) is considered a potential alternative to traditional farmer practices. However, its physiological mechanisms for enhancing rice N utilization and its effects on paddy field N balance remain unclear. We aimed to elucidate the potential enzymatic mechanisms underlying LCC’s influence on rice N use and quantify the impact of LCC on paddy field N balance. In 2022 and 2023, a single-factor randomized block design experiment was conducted during the rice planting season. Four N treatments: no N (ONF), farmers’ conventional practices + urea [FNR] as the control, LCC + urea [SSNM1], LCC + controlled-release urea [SSNM2] were administered. Rice yield and N uptake were positive correlations with nitrate reductase (NR), glutamine synthetase (GS), glutamate-pyruvate transaminase (GPT), glutamate-oxaloacetate transaminase (GOT) and glutamate dehydrogenase (GDH) activities, which were higher under SSNM1 and SSNM2 compared with FNR, but were negative correlation with proteinase activity. Moreover, SSNM1 and SSNM2 increased rice yield by 9.2% and 9.4%, N uptake by 15.4% and 15.3%, and N use efficiency by 46.9% and 65.0%, and reduced reactive N losses by 46.2% and 66.7%, respectively. The annual net soil N inputs under FNR, SSNM1, and SSNM2 were 12.6, 8.9, and 4.2 kg N ha⁻¹, respectively. LCC-based N management increased N uptake and rice yield by enhancing the activities of NR, GS, GPT, GOT, and GDH while reducing protease activity. Moreover, LCC maintained soil N supply capacity even with reduced nitrogen fertilizer application. Full article

Dry topsoil restricts root growth and nutrient uptake in arid regions, thereby significantly reducing crop yield. Hydraulic lift occurs due to the dry topsoil and wet deep soil. This study investigates the effects of topsoil drought intensity (three field capacities in topsoil: 60–70% (W1), 50–60% (W2), and 40–50% (W3)) and nitrogen application rate (N1: 120, N2: 240, and N3: 360 kg ha⁻¹) on cotton quality and the distribution of nitrogen in soil and plant under hydraulic lift using a root-splitting device. The upper pot of the root-splitting device was 22 cm high, with a 26 cm top diameter and a 23 cm bottom diameter; the lower pot of the root-splitting device was 45 cm high, with a 48 cm top diameter and a 36 cm bottom diameter. Topsoil moisture was maintained at W1 without nitrogen application under the control treatment (CK). The W2 and W3 treatments (representing different topsoil drought intensities) were designed to compare the interactive effects of water and nitrogen fertiliser on nitrogen distribution and cotton quality with the CK treatment. Results indicate that the concentrations of nitrate nitrogen (NO₃⁻-N) in the 10–20 cm soil were generally higher than those in the 0–10 cm soil. The topsoil drought intensity and nitrogen application rate had significant impacts on nitrogen concentrations in cotton organs. The W2 treatment produced the maximum nitrogen concentration, except for the root nitrogen concentration in 2021. The nitrogen concentration in the roots and stems peaked at 240 kg ha⁻¹ of nitrogen application rate. The topsoil drought intensity and nitrogen application rate had considerable influences on the cotton dry matter. The nitrogen application rate had a significant impact on the following indexes: internal nitrogen-fertiliser use efficiency (INUE), physiological nitrogen-fertiliser use efficiency (PNUE), and nitrogen-fertiliser recovery efficiency (NRE), except for PNUE in 2020. The INUE of other treatments decreased by 13.82–43.44% compared with CK treatment. In 2021, fibre length and elongation were significantly impacted by the topsoil drought intensity, nitrogen application rates, and their interactions. The nitrogen application rate’s effects on the uniformity index were significant in 2020 and 2021. The hydraulic lift magnitude, NRE, and NO₃⁻-N in the 0–10 cm soil were significantly correlated with each other. There were correlations among cotton quality indexes: fibre length and strength, uniformity index and micronaire, and micronaire and elongation. These findings provide a reference for future research on the mechanism by which hydraulic lift participates in nitrogen distribution in soil and crops and also offer a new direction to utilize deep water to improve the utilization rate of water resources. Full article

NIN-like proteins (NLPs) are conserved, plant-specific transcription factors that play crucial roles in the nitrate signaling response, plant growth and development, and abiotic stress responses. However, their functions have not been explored in sweet potato. In this study, we identified 7 NLPs in cultivated hexaploid sweet potato (Ipomoea batatas, 2n = 6x = 90), 9 NLPs in the diploid relative Ipomoea trifida (2n = 2x = 30), and 12 NLPs in Ipomoea triloba (2n = 2x = 30) via genome structure analysis and phylogenetic characterization, respectively. The protein physiological properties, chromosome localization, phylogenetic relationships, syntenic analysis maps, gene structure, promoter cis-acting regulatory elements, and protein interaction networks were systematically investigated to explore the possible roles of homologous NLPs in the nitrate signaling response, growth and development, and abiotic stress responses in sweet potato. The expression profiles of the identified NLPs in different tissues and treatments revealed tissue specificity and various expression patterns in sweet potato and its two diploid relatives, supporting differences in the evolutionary trajectories of the hexaploid sweet potato. These results are a critical first step in understanding the functions of sweet potato NLPs and offer more candidate genes for improving nitrogen use efficiency and increasing yield in cultivated sweet potato. Full article

Root architecture and anatomy critically regulate maize nitrogen (N) acquisition, but their coordinated low-N response in N-efficient hybrids remains poorly understood. Elucidating this mechanism is essential for advancing root system regulation and breeding strategies aimed at enhancing N-use efficiency. In this study, six root architectures, twelve root anatomies, and six N-efficiency traits were evaluated in six maize hybrids and nine parental inbreds under sufficient (SN, 180 kg ha⁻¹) and low N (LN, 30 kg ha⁻¹), with transcriptome analysis of inbreds applied to uncover mechanisms. Hybrids were categorized as follows: EE (N-efficient under both N levels), SNE (N-efficient only under SN), and NN (inefficient under both N). Compared with other hybrids, EE developed a 6.0–15.7% narrower root opening angle (ROA), a 11.9–12.4% larger root projected area (RPA), 16.3–22.6% deeper roots (D_Wmax), and 22.6–37.1% more cortical aerenchyma (AA) under LN; SNE showed 9.49–19.51% lower RPA and higher LN-induced reductions in D_Wmax (8.84–17.09%); NN exhibited the largest ROA (60.75–64.48°) and LN-induced reductions in RPA (16.43%), D_Wmax (14.76%), and total projected structure length (11.28%). Correlation, principal component, and structural equation modeling analyses revealed significant root architecture–anatomy integration, and they collectively influence yield through traits such as D_Wmax, AA, and xylem vessel area (XVA) (r = −0.48–0.62, path coefficients: 0.19–0.27). Additionally, the EE and NN hybrids inherited and integrated the superior N-efficient root phenotypes from their parental inbred lines. Transcriptomic analysis identified eight root development genes, including GRMZM5G878558, whose expression correlated with both D_Wmax and AA (r = 0.61–0.73). These findings clarified that N-efficient maize achieved higher yield through coordinated root architecture–anatomy optimization involving associated genes, providing a theoretical foundation for N-efficiency-targeted root regulation and varietal selection. Full article

Subsurface drip irrigation can improve crop water and fertilizer use efficiency, but it can cause soil hypoxia. We report on experiments performed in Aksu Prefecture, Xinjiang (41°17′ N latitude, 80°17′ E longitude), from April 2023 to October 2024 using oxygenated drip irrigation from the surface to 50 cm depth in an apple (Malus pumila Mill.) orchard, to examine the effects of drip irrigation on inter-root hypoxia, tree growth, fruit quality, and yield. Compared with surface oxygenated drip irrigation (CK), irrigating at 10 and 30 cm increased soil water content in the root system, elevated gibberellin, zeatin ribosides, and indoleacetic acid contents and reduced abscisic acid contents in new shoot tips. Compared with CK, branch and leaf nitrogen, phosphorus, and potassium contents were increased with irrigation at depths of 10 and 30 cm. The leaf nitrogen (N), phosphorus (P), and potassium (K) contents were increased by 18.03%, 22.42%, and 16.63%, respectively, in the treatment with a burial depth of 30 cm. Among treatments, irrigation at 30 cm produced the highest average daily plant water potential, and irrigation at 50 cm was the lowest. Maximum leaf soil–plant analysis development (SPAD) values occurred when irrigated at 30 cm, and minimum values occurred at 50 cm. For both years, the largest range of light flux utilization occurred when irrigated at 30 cm and the lowest when irrigated at 50 cm. Significant correlations between indoleacetic acid (IAA), total gibberellin (GA), zeatin riboside (ZRs), leaf N content, leaf K content, plant water potential (PWP), net photosynthetic rate (Pn), SPAD, and apple yield were determined by partial mantel analysis. A significant correlation was found between abscisic acid (ABA), IAA, GA, leaf P and K content, and apple quality. Principal component analysis revealed a burial depth of 30 cm had the highest principal component composite score, indicating that this burial depth, and oxygenation and fertilization regime most favored apple growth, yield, and quality. Full article

The development of electrocatalysts composed of earth-abundant elements is essential for advancing the commercial application of Proton Exchange Membrane Fuel Cells (PEMFC). Among these, single-atom electrocatalysts, such as Fe-N-C, show great promise for the oxygen reduction reaction (ORR). This study aims to improve the ORR activity and stability of Fe-N-C electrocatalysts by fine-tuning the straightforward 1,10-phenanthroline-iron complexation synthesis method. Key parameters, including iron-to-phenanthroline ratio, carbon powder surface area, and pyrolysis temperature were systematically varied to evaluate their influence on the resulting electrocatalysts. The findings of this study revealed that the electrocatalysts synthesized with 1,10-phenanthroline (Phen) and high-surface-area Black Pearls (BP) possessed much better ORR activity than electrocatalysts prepared by using Vulcan carbon (lower surface area). Interestingly, electrocatalysts prepared with BP, but with a non-bidentate nitrogen-containing ligand molecule, such as imidazole, showed a much poorer activity, as the resulting material predominantly consisted of inactive structures, such as encapsulated iron nanoparticles and iron oxide, as evidenced by HR-TEM, EXAFS, and XRD. Therefore, the results suggest that only the synergistic combination of the bidentate ligand phenanthroline (Phen) and the high-surface-area carbon support (BP) favored the formation of ORR-active Fe-N-C single-atom species upon pyrolysis. The study also unveiled a significant enhancement in electrocatalyst stability during accelerated durability tests (and air storage) as the pyrolysis temperature was increased from 700 to 1300 °C, albeit at the expense of ORR activity, likely resulting from the generation of iron particles. Pyrolysis at 1050 °C yielded the electrocatalyst with the most favorable balance of activity and stability in rotating disk measurements, while maintaining moderate durability under PEM fuel cell operation. The insights obtained in this study may guide the development of more active efficient and durable electrocatalysts, synthesized via a simple method using earth-abundant elements, for application in PEMFC cathodes. Full article

Rebar is a critical material in concrete constructions like high-rise buildings and seismic-resistant structures. To enhance its properties, microalloying with nitrogen is employed, but traditional methods using micro alloy additives such as vanadium (FeV), niobium (FeNb), titanium (FeTi), and vanadium nitride (VN) face issues of high costs, reduced purity, and difficulty in controlling molten steel composition. This article presents a novel approach of injecting top-blown O₂–N₂ mixed gas to increase nitrogen content efficiently. Experiments simulated HRB400 steel samples, varying N₂ ratios (10%, 20%, 30%, 40%), temperatures (1500 °C, 1550 °C, 1600 °C), and blowing times (1, 2, 3 min). Results show that optimized parameters enable nitrogen content adjustment from 50 to 104 ppm, with nitrogen utilization improved to 5.4%. This method utilizes inexpensive N₂ gas, reduces impurities, and provides precise control, offering a cost-effective and sustainable solution for high-performance steel production by replacing costly alloys and meeting nitrogen requirements. Full article

To explore fertilization strategies that achieve both high yield and emission reduction in greenhouse tomato production, a two-season experiment was conducted in autumn 2023 and spring 2024 under equal nitrogen input. Seven treatments were established: conventional fertilization (CK1), biogas slurry alone (CK2), 0.5% biochar + biogas slurry (T1), 2% biochar + biogas slurry (T2), dicyandiamide + biogas slurry (T3), 0.5% biochar + biogas slurry + dicyandiamide (T4), and 2% biochar + biogas slurry + dicyandiamide (T5). The effects of each treatment on tomato root traits, yield, irrigation water use efficiency (IWUE), partial factor productivity of nitrogen (PFPN), and soil N₂O emissions were systematically evaluated. An analytic hierarchy process (AHP) was applied for comprehensive assessment. The results showed that fertilization treatments significantly affected tomato root traits (p < 0.05), with T5 exhibiting the best performance in root length, average diameter, total surface area, total volume, and root activity, all significantly higher than CK1. T5 also achieved the highest yield in both seasons, with increases of 8.13% (autumn 2023) and 10.19% (spring 2024) over CK1. Moreover, T5 showed superior IWUE (475.38 kg ha⁻¹ mm⁻¹) and PFPN (405.92 kg kg⁻¹). In terms of environmental performance, T5 significantly reduced soil N₂O flux, with the largest reduction reaching 16.16%, particularly during the peak emission stages in the flowering and fruit-setting periods. The AHP-based comprehensive evaluation confirmed that T5 had the highest overall weight with satisfactory matrix consistency. In conclusion, compared with conventional fertilization, the integrated T5 treatment increased tomato yield by up to 10.19% and reduced cumulative N₂O emissions by up to 16.16%, highlighting its potential as a feasible fertilization pathway and technical reference for low-carbon and sustainable agriculture. Full article

The yield-enhancing effect of nitrogen (N) in sugar beets depends on the appropriate balance of other nutrients, including potassium (K) and magnesium (Mg). To determine the effects of these nutrients on beet yield (BY), quality parameters, white sugar yield (WSY), and nitrogen use efficiency (NUE) indices, a three-year field study was conducted in western Poland. Eight different fertilization treatments with potassium salt (PS), Korn-Kali (KK), and magnesium sulfate (Mg) were tested, K₀, K₁ (PS), K₂ (PS), K₂ (PS) + Mg, K₁ (KK), K₂ (KK), K₂ (KK) + Mg, K₂ (KK) + Mg + FF, where 0, 1, and 2 are the K rates, respectively, for 0, 83, and 163 kg K ha⁻¹, and FF denotes foliar fertilization with magnesium sulfate. Potassium fertilization, both in the form of PS and KK, along with additional application of magnesium sulfate, positively affected BY and WSY. However, the response to fertilization depended strongly on seasonal factors, such as weather and soil conditions. Compared to the treatment without potassium (K₀), the average BY increased by 6.5–9.1%, and the WSY by 4.6–9.0%. Mineral fertilization had little effect on taproot quality parameters, including sucrose content. The exception was the concentration of α-amino-N, which significantly decreased with the application of K fertilizers. However, changes in α-amino-N content were not significantly related to WSY levels because this characteristic primarily depended on BY each year, and applying K and Mg to the soil improves NUE indices. Full article

Nitrogen is an essential nutrient for the growth and development of maize (Zea mays L.), and soil nitrogen deficiency is an important factor limiting maize yield. Although excessive application of nitrogen fertilizer can increase yield, it can also cause environmental problems. Therefore, screening low-nitrogen-tolerant (LNT) germplasm resources and analyzing their genetic mechanisms are of great significance for the development of efficient and environmentally friendly agriculture. In this study, 201 maize inbred lines were used as materials. Two levels of low nitrogen (LN) (0.05 mmol/L, N1) and normal nitrogen (4 mmol/L, N2) were set up. Phenotypic indicators such as seedling length, root length and biomass were measured, and they were classified into LNT type (18 samples), nitrogen-sensitive (NS) type (27 samples) and intermediate type (156 samples). A total of 47 significant SNP loci were detected through a genome-wide association study (GWAS), and 36 candidate genes were predicted. Transcriptome sequencing (RNA-seq) analysis revealed that the differentially expressed genes (753 upregulated and 620 downregulated) in LNT materials under low nitrogen stress (LNS) were significantly fewer than those in NS materials (2436 upregulated and 2228 downregulated). Further analysis using WGCNA identified a total of eight co-expression modules. Among them, the red module was significantly correlated with root length and underground fresh weight under LN conditions (r = 0.75), and three key genes for stress response (Zm00001d005264, Zm00001d053931, Zm00001d044292) were screened out. Combined with GWAS, RNA-seq and qRT-PCR verification, eight candidate genes closely related to LNT at the seedling stage of maize were finally determined, involving biological processes such as stress response, nitrogen metabolism and substance formation. This study initially revealed the molecular mechanism of maize tolerance to LN through multi-omics analysis, providing a theoretical basis and genetic resources for breeding new nitrogen-efficient maize varieties. Full article

This study aimed to identify candidate genes associated with chlorophyll content in rice via genome-wide association studies (GWAS) and to develop molecular markers for the selection of genetic resources and breeding lines exhibiting high chlorophyll content. Measurement of the Soil and Plant Analysis Development (SPAD) values, indicative of chlorophyll content and photosynthetic potential, were measured in 198 rice genetic resources across three years under consistent nitrogen conditions. Nitrogen fertilizer (as urea) was applied at a rate of 90 kg N ha⁻¹. After analyzing the multi-year SPAD data, genetic resources with the coefficient of variation (CV) value exceeding 20% were excluded, and the remaining 175 accessions were used for subsequent analyses. Population structure analysis using the principal component analysis (PCA) and phylogenetic methods confirmed clear genetic differentiation, supporting the reliability of the GWAS. A GWAS using 289,569 SNPs identified 17 significant loci, among which four quantitative trait loci (QTLs)—qSV3-1, qSV3-2, qSV6, and qSV7—explained over 20% of phenotypic variance. Analysis of their additive effects revealed distinct SPAD distributions among QTL combination groups, with accessions harboring all four QTLs exhibiting the highest values. Candidate gene analysis within ± 200 kb of lead SNPs identified Os03g079100 (OsUCL8), involved in photosynthesis, near qSV3-2. A derived cleaved amplified polymorphic sequence (dCAPS) marker was developed to differentiate alleles at this locus and validated via restriction digestion. These results provide key genetic insights into chlorophyll accumulation and offer molecular markers for breeding high-yielding rice cultivars with enhanced chlorophyll content. The results of this study are expected to contribute to the development of sustainable rice varieties by utilizing the developed markers and identified candidate genes to increase SPAD values, thereby enhancing nitrogen use efficiency, improving photosynthetic capacity, and ultimately increasing rice productivity. Full article