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• Anodic oxidation coating's cracking causes a severe substrate stress concentration. • Sealing weakens anodic oxidation coating's cracking resistance during fatigue tests. • Prior shot peening enhances the fatigue property of anodic oxidation coated specimen. In this study, the effects of sealing and prior shot peening treatments on the fatigue behavior of the sulphuric acid anodic oxidation coated 6082-T6 aluminium alloy were investigated. Experimental results indicate that the preferential fracture of anodic oxidation coatings due to its higher brittleness and lower fracture toughness as well as the stress concentration of near-interface substrate caused by the interface cyclic dislocation accumulation could cause the fatigue failure of anodic oxidation coated specimens. Consequently, the fatigue property of anodic oxidation coated specimens notably decreases compared to as-machined specimens, with a decrease of 26.7 % in the fatigue limit corresponding to 2 × 107 fatigue cycles. Additionally, the sealing treatment introduces numerous cracks that penetrate the coating entirely, diminishing the coating's resistance to cracking under fatigue loading; this alteration changes the fatigue failure mechanism of anodic oxidation coated specimens, ultimately resulting in a decrease of 15.5 % in the fatigue limit of anodic oxidation coated specimens. Despite exacerbating the surface integrity and increasing the surface roughness of anodic oxidation coated specimens, the prior shot peening treatment increases the fatigue limit of anodic oxidation coated specimens by 82.8 % since the affecting layer beneath the interface plays a crucial role in inhibiting the further propagation of coating cracks into the substrate as well as the crack propagation in the substrate beneath the interface. [ABSTRACT FROM AUTHOR]

• The UPM and PI iterative methods can accurately reconstruct the residual stress field induced by rolling processing. • The extended finite element method and the weight function method are applied to solve the stress intensity factor. • The necessity of deep rolling treatment for axles is verified. • The influence of interference and initial crack position on the remaining life of axle is explored. • The damage tolerance analysis of the axle was carried out. Deep rolling surface strengthening is an effective way to introduce compressive residual stress (CRS) along the railway axle, which can improve the fatigue resistance of the material. The CRS field was rebuilt adopting the proportional-integral (PI) iteration method and the unit pressure method (UPM) to study the fatigue cracking behavior of deep-rolled EA4T railway axles. The remaining life prediction model and the stress intensity factor (SIF) solution method were then validated using simulations and testing with small-sized specimens. The remaining life of the EA4T railway axle was then calculated by applying a realistic vertical load spectrum. The results showed that CRS prevented crack propagation, enhanced the critical propagation size of railway axle cracks, and prolonged the remaining life of the axle. Additionally, the remaining life of the axle may not support the following maintenance period if a crack with an extendable size emerges at the unloading groove of the railway axle. This work provides a theoretical basis for the optimization of the non-destructive testing (NDT) interval of deep-rolled EA4T railway axles. [ABSTRACT FROM AUTHOR]

• Prior shot peening improves the CF limit of AO coated aluminum alloy by 50 %. • AO specimens exhibit different CF failure modes under low and high applied stress. • Substrate residual stress and microstructure affect the CF crack propagating path. • Substrate residual stress relaxes in distinct mode under low and high applied stress. Plain (anodic oxidation) and composite (prior shot peening + anodic oxidation) coatings were prepared to investigate their effects on the corrosion-fatigue (CF) property of 6082-T6 aluminium alloy in a 3.5 wt% NaCl aqueous solution. The results indicate that plain coated specimens exhibited similar CF properties to as-machined specimens at low applied stresses. However, under high applied stresses, the plain coating led to a preferential fracture and was unable to effectively prevent corrosion medium. Hence, the CF property of plain coated specimens was found to be inferior to as-machined specimens at high applied stresses. The synergetic effect of substrate residual stress and microstructure beneath the coating-substrate interface reduced the crack propagating rate in the initial stage by deflecting the crack at the grain boundary. Therefore, the CF property of composite coated specimens improved as a whole when compared with as-machined and plain coated specimens. Besides, under low applied stresses, the near-interface substrate residual stress of composite coated specimens occurred the relaxation due to the substrate crack propagation, while under high applied stresses, this was due to the synergetic effect of materials' local cyclic yield and plastic flow, as well as the substrate crack propagation. [ABSTRACT FROM AUTHOR]

• The surface properties of EA4T axle steel treated by ultrasonic surface rolling process (USRP) are investigated. • Effect of USRP on the electrochemical corrosion resistance and corrosion fatigue performance is elucidated. • Residual stress relaxation mechanism of USRP-treated EA4T axle steel in air and corrosion is revealed. • Influence of residual stress relaxation on the corrosion fatigue resistance is clarified. The fatigue properties and residual stress relaxation behavior of EA4T axle steel treated by ultrasonic surface rolling process (USRP) are investigated in air and corrosive environments. The result reveals that the surface roughness (Ra) is decreased from 1.42 to 0.17 μm after the USRP. A surface layer with ultrafine grains, work hardening, and compressive residual stress (CRS) is achieved by the USRP. Compared with the as-machined specimens, the USRP specimens exhibit slightly lower electrochemical corrosion resistance but superior fatigue performance in air and corrosive environments. The dislocation density is significantly decreased in the corrosive environment during fatigue loads, accompanied by a rapid relaxation of surface CRS. The influence of USRP on the corrosion fatigue performance is elucidated. The residual stress relaxation mechanism and its influence on fatigue resistance are also analyzed. [ABSTRACT FROM AUTHOR]

This work reports micro-defects and growth mechanism of the plasma electrolytic oxidation (PEO) coating formed on the surface of 6082-T6 aluminum alloy. Scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray computed tomography techniques were used to characterize the morphology, phase, microstructure, and porosity of the PEO coating, respectively. The results confirmed a porous outer layer and a dense inner layer in the coating. The PEO coating was composed of γ- and α-Al 2 O 3 phases, and amorphous phases. A layer with only amorphous structures was found near the coating/substrate (C/S) interface, which could be ascribed to the high concentration of P element in the electrolyte. Micro-defects with different sizes and shapes inside the coating were successfully characterized by the high-resolution X-ray computed tomography technique, and the volume reconstruction result revealed a porosity fraction of 5.43% for the coating. A growth model was complemented to explain the growth mechanism and interconnected micro-defects of the PEO coating. • Micro-defects in the plasma electrolytic oxidation (PEO) coating formed on 6082-T6 alloy were firstly characterized by high-resolution X-ray computed tomography technique. • Formation of the amorphous structure at the coating/substrate (C/S) interface was highly dependent on P element in the electrolyte. • Growth mechanism of the coating was clarified based on the microstructural observation and micro-defect characterization. [ABSTRACT FROM AUTHOR]

Low, medium and high-intensity (0.19, 0.26 and 0.34 mmA) shot peening treatments and 0.34 mmA high-intensity shot peening combined with slight and severe polishing treatments were used as the pre-treatments to improve the fatigue property of micro-arc oxidation (MAO) coated 6082-T6 aluminum alloy, respectively. In consideration of the significance of substrate residual stress beneath the coating-substrate interface on MAO coated specimens' fatigue property, the substrate residual stress of various coated specimens was analyzed by the X-ray's powerful penetrability. Results indicate that the substrate residual stress state of MAO coated specimens is changed from tensile (+93 MPa) to compressive (−65 to −93 MPa) by the above pre-treatments, which is beneficial for inhibiting the crack initiation at the substrate or resisting the crack's further propagation from the coating into the substrate. Whereas, similar to the compressive residual stress induced by shot peening, the compressive substrate residual stress for prior shot peening + MAO composite coated specimens will also relax during the fatigue tests. In addition, the gradient compressive residual stress beneath the interface induced by prior shot peening reduce the crack propagating rate, thus improving the fatigue property of coated specimens; after the 0.26 mmA shot peening pre-treatment, the fatigue strength at 2 × 107 cycles of MAO coated specimens increases by 59.1 %. Finally, the effects of surface and interface roughness, substrate residual stress and in-depth compressive residual stress on the fatigue life of MAO coated specimens are further discussed. • Pre-treatments improve MAO coated Al alloys' fatigue life by 2.41 to 4.35 times. • Grain refinement of substrate increases MAO coatings' pore size and thickness. • Compressive substrate residual stress inhibits crack propagation beneath interface. • Compressive substrate residual stress relaxes by 8 % to 41 % at 104 fatigue cycles. [ABSTRACT FROM AUTHOR]

• CSP and MSP are used to improve the fatigue property of bare and MAO coated Al. • CSP and MSP introduce a grain-refined and CRS affected layer on surface. • CSP and MSP is more appropriate for MAO coated and bare Al, respectively. • Crack initiation stage dominates the fatigue property of bare Al. • Crack propagation stage dominates the fatigue property of MAO coated Al. Conventional shot peening (CSP) and micro-shot peening (MSP) are used to enhance the fatigue property of bare and micro-arc oxidation (MAO) coated 6082-T6 aluminum. The difference in the anti-fatigue strengthening mechanism of CSP and MSP on bare and MAO coated 6082-T6 aluminum alloy is revealed. Results show that MSP provides a more significant improvement in fatigue properties of bare specimens than CSP since the intensely inhibiting effect on crack initiation. Nevertheless, MAO coating impairs the surface integrity of MSP specimens, thus reducing the crack initiating life. In comparison, the effect of deeper affected layer induced by CSP on the improvement of crack propagating life is mostly retained after the MAO process. Hence, for the MAO coated specimen, the CSP prior-treatment is more effective in improving its fatigue property. [ABSTRACT FROM AUTHOR]

• Fatigue life prediction method of 25CrMo4 steel is investigated using fracture mechanics and machine learning methods. • Residual stress relaxation process is incorporated into fatigue crack growth in combination with NASGRO equation and equivalent initial flaw size (EIFS) methodology. • Different machine learning methods areemployed to investigate theireffectiveness in fatigue life prediction. In this work, fracture mechanics and machine learning methods are separately employed to predict the high cycle fatigue (HCF) life of micro-shot peened 25CrMo4 alloy steel containing artificial notches. The influences of notch size, stress level, and surface condition on fatigue life are incorporated into the prediction model. The results shows that the fatigue life of shot-peened specimens is enhanced by the compressive residual stress (CRS) compared with that of the un-peened specimens. The prediction result using fracture mechanics method is within the error band of ±2, while that using machine learning method almost lies in the error band of ±1.5. The stress level and notch size are the most critical factors affecting the HCF fatigue life. The applicability and limitation of the two methods are finally discussed. [ABSTRACT FROM AUTHOR]

The effects of micro-shot peening (MSP) and artificial surface defects were investigated in relation to the defect tolerance of Al-Si-0.6Mg alloy in the framework of fracture mechanics. The results indicated that coral-shaped casting defects inside the alloy could be effectively quantified using the X-ray synchrotron radiation technique. An affected layer with a surface roughness (Ra) of 1.25 and residual stress of − 125 MPa was introduced on the MSP specimen compared to the un-peened (UP) specimen. The fatigue strengths of the UP and MSP specimens containing the artificial defects decreased as the defect size increased under rotating bending fatigue tests, except in the case of defects with the equivalent size of 395 and 490 µm, respectively. MSP could shift the crack initiation site toward the subsurface, while all the cracks of the specimens with the artificial defects originated from the surface and maintained an aspect ratio of 0.66 during the crack growth process. The relationship between the defect sizes and the fatigue strengths could be reasonably assessed by the modified Kitagawa-Takahashi (K-T) diagrams. The critical defect size of the MSP specimens was increased from 450 to 542 µm compared with that of the UP specimens, owing to the beneficial effect of the compressive residual stress. The defect tolerance of the Al-Si-0.6Mg alloy was improved by the MSP process. • Effects of micro-shot peening (MSP) on the fatigue properties of Al-Si-0.6Mg alloy are explored. • Casting defect inside the alloy was identified using synchrotron radiation X-ray computed microtomography (SR-μCT) technique. • The influence of MSP on the fatigue tolerance was characterized by Kitagawa-Takahashi (K-T) diagrams. • The critical defect size harmless to fatigue strength was evaluated using fracture mechanics. [ABSTRACT FROM AUTHOR]

• Effects of the corrosive environment on the fatigue strength of EA4T axle steel are explored. • The evolution of corrosion process during fatigue loading is fully investigated. • Crack aspect ratio in the corrosive environment is obtained by using synchrotron radiation X-ray computed microtomography (SR-μCT). • Fatigue life prediction model is developed based on the pit growth, short crack growth, and long crack growth stages. High-speed railway axle is the critical safety component of modern ground vehicles, which experiences extremely complex environments. In this paper, the effect of corrosion on the fatigue behavior of EA4T axle steel was investigated in an artificial rainwater environment. Combining scanning electron microscopy (SEM) and synchrotron radiation X-ray micro computed microtomography (SR-μCT) with theoretical analysis, damage measurement enabled a full evolution characterization of the corrosion process for exploring the corrosion mechanism and its influence on the fatigue life. It is found that the corrosive environment significantly reduced fatigue strength and facilitated multiple crack initiation, while showed relatively little effect on the long fatigue crack growth. The fitness of the 3-P Weibull distribution was slightly higher than that of the Gumbel distribution in terms of crack population. The life prediction model incorporating the pit growth, short crack, and long crack stages showed a good agreement within the 95% and 5% probabilistic S-N curve. [ABSTRACT FROM AUTHOR]

• The extended finite element method is used in the fracture mechanics simulation of EA4T axle steel specimen and full-scale axle. • Numerical model is built considering residual stress and wheelset press-fitting. • The effectiveness of the extended finite element method (XFEM) was verified by comparing the simulation and experimental results. • The measured load spectrum was applied, and the NASGRO equation was used to calculate the residual life of the axle. High-speed railway axles may be damaged during service or maintenance. Therefore, to ensure axle service safety, the residual life of damaged axles is necessary for an accurate assessment. In this study, a small-sized specimen was analyzed and the effectiveness of the extended finite element method (XFEM) was verified by comparing the simulation and test results. Subsequently, the residual life of the EA4T axle with an initial crack was evaluated using the XFEM, which is based on fracture mechanics, and the actual axle service load spectrum. The results show that the critical failure sizes for the residual life of the power axle and non-power axle were 7 and 4 mm, respectively, for a crack located in the middle of the axle body; in contrast, for a crack located in the arc transition of the wheel seat, the critical failure dimensions were 9 and 5 mm, respectively. Based on the NASGRO equation and considering the damage tolerance safety factor, the residual lives of the power axle for the two crack locations were estimated to be 1.3953 × 106 and 9.636 × 105 km, respectively, while those of the non-power axle were 2.095 × 106 and 1.2583 × 106 km, respectively. The results of this study can provide a reference for the axle non-destructive testing (NDT) period. [ABSTRACT FROM AUTHOR]

• Cause and consequence analysis for industrial hot work is conducted. • The ABT model and PN are integrated to analyze hot work accident evolution. • An improved regional center method is developed to obtain crisp evaluation value. • Data fitting is performed for probability calculation. Hot work poses great hazards to industrial operation site. Although regulatory and guidance exist, accidents caused by hot work continue to occur. Risk assessment has proved to be an effective method for risk control. However, current studies paid less attention to the evolution process of industrial hot work accidents and the quantitative risk assessment seems to be insufficient. In this context, we aimed to perform comprehensive risk evolution analysis and quantitative risk assessment of hot work using adaptive bow tie (ABT) and Petri nets (PNs). The ABT model is improved to analyze deep causes, consequences, and their relationships. PNs are employed to conduct quantitative risk assessment. To address uncertainties, the triangular membership function and improved regional center method are proposed to calculate the confidences of all places and transitions in the PNs. The probabilities are finally obtained by data fitting method. The study found that the most likely consequence of hot work accident is near miss. The results also indicate that hot work accident prevention measures should emphasize on the isolation of workplace, combustible gases test, removal of combustible substances, job organization, and job training. Besides, emergency devices maintenance and emergency drilling are critical to prevent accidents from expanding. [Display omitted] [ABSTRACT FROM AUTHOR]

It's well known that the development and distribution of roots could be regulated to obtain deep soil resource and enhance the grain yield by increasing the depth of fertilization, but little is known about whether increasing P fertilization depth can optimize the root distribution to delay leaf senescence, enhance photosynthetic performance and root-shoot coordination or not. We conducted a field experiment that tested the following four placement depths of P fertilization: 5 cm (P 5), 10 cm (P 10), 15 cm (P 15), and 20 cm (P 20). The experiment was designed to explore the regulatory effects of the P fertilization depth on the root growth and distribution, the photosynthetic performance, the root-shoot coordination, the yield formation, the N and P fertilizer utilization of maize plants. We found that deep P placement did indeed alter the root parameters. In the 20–60 cm soil layer, both the root dry weight and length of P 15 treatment were on average 23.2% higher than those of P 5 treatment. The specific root length and specific root surface area of P 15 treatment were 4.5% and 5.6% higher than those of P 5 treatment. In addition, the P 15 treatment achieved a significantly improved photosynthetic performance over the P 5 treatment: The leaf area index at the R6 stage was 10.2% higher, the leaf senescence index from the R2 to the R6 stages was 31.4% lower, the photosynthetic rate at the R3 stage was 25.9% higher. The P placement depth also optimized the root-shoot coordination: The ratios of root weight to shoot weight, root surface area to leaf area, and root length to leaf area of P 15 treatment were 6.7%, 13.8%, and 12.7% higher than those of P 5 treatment, respectively. Finally, the root P and N uptake efficiency, the photosynthetic P-use efficiency, and the physiological P-use efficiency of P 15 treatment were all significantly higher than those of P 5 treatments. And together these responses had the effect of increasing the mature biomass by 12.5%, and the grain yield by 22.0%. In conclusion, increasing the P fertilization placement depth to 15 cm regulates the growth and development of the root system, which in turn improves the capability of plant to uptake and utilize N and P in the soil, delays the onset of leaf senescence, enhances its photosynthetic performance and biomass accumulation rate, and thus ultimately increases the yield. [Display omitted] • Deep P fertilization optimizes root growth, and root-shoot coordination. • Deep P fertilization delays leaf senescence and improves photosynthetic performance. • Optimized root-shoot coordination improves the grain yield and nutrient use efficiency. [ABSTRACT FROM AUTHOR]

• Vanadium addition causes an increase in both yield strength and yield ratio. • Vanadium addition reduces strain hardening ability, and weakens wear resistance. • RCF crack initiation of V-alloyed stee is delayed by increasing yield strength. • RCF crack growth size is restricted by reducing plastic deformation capacity. • Increasing yield ratio improves RCF resistance, but weakens wear resistance. This study aims to evaluate the effect of vanadium microalloying on rolling contact fatigue (RCF) and wear behavior of railway wheel steels. It involves microstructural analysis and mechanical testing, including hardness, tensile, and rolling/sliding tests on the test steels, followed by electron backscatter diffraction, residual stress, and microhardness analyses after rolling/sliding tests. The findings demonstrate that vanadium microalloying leads to the alleviation of dynamic recrystallization, strain hardening, and compressive residual stress within the outermost layer beneath the worn surface, indicating a reduction in the plastic deformation capacity during dry rolling/sliding conditions. RCF resistance of railway steel can be enhanced through vanadium microalloying, as it simultaneously delays crack initiation by increasing yield strength and restricts crack growth by reducing plastic deformation capacity. While vanadium microalloying enhances the matrix hardness of wheel steel, it concurrently diminishes its strain hardening ability, potentially compromising its wear resistance. In addition, this study found that the yield ratio, being indicative of plastic deformation capacity and strain hardening ability, can serve as a suitable parameter for characterizing the RCF and wear resistances of tested steels. It exhibits a positive correlation with RCF resistance and a negative correlation with wear resistance. [ABSTRACT FROM AUTHOR]

• The overset mesh technology is used to simulate the train running in the tube. • The flow topology considering the ground effect has been visualized numerically. • The influence of the nose length on the wave systems is reported. • Two distinct mechanisms for the formation of flow separation are identified. • The relationship between the aerodynamic loads and flow structures is described. The flow structure and aerodynamic loads in evacuated tube transportation with three nose lengths (5, 10 and 15 m) at 1500 km/h are investigated by overset mesh technology. The governing equations of the IDDES model for 3-D, unsteady compressible flow are employed. The numerical algorithm is validated via moving model and wind tunnel experimental data. The flow topology considering the ground effect is revealed and compared. The wake is highly complex, characterized mainly by wave systems and trailing vortices. Additionally, the influence of the nose length on the generation of wave systems is discussed in detail. The largest shock intensity is identified at 5 m case, followed by 15 m case, and the smallest case at 10 m. Differences in wave systems also caused the two distinct mechanisms for the formation of flow separation and the evolution pattern of the wake vortex to be identified for three nose configurations. By comparison, the nose length increase is helpful to reduce the length of the disturbed region of the leading shock wave, the aerodynamic loads on the train surface and aerodynamic drag. A qualitative description is also presented of the relationship between the fluctuations of aerodynamic loads and flow structures. [ABSTRACT FROM AUTHOR]

With the extensive promotion of controlled-release urea (CRU), its N-release pattern has been shown to match the crop's N-demand period and improve crop yield by reducing N losses. Nevertheless, the impacts of CRU on summer maize yield, especially on greenhouse gas emissions, have rarely been reported during its long-term use. It is necessary through long-term positioning field experiment with CRU application to investigate the regulatory mechanisms of maize yield formation, nitrogen use efficiency (NUE), ammonia volatilization and greenhouse gas emissions. The long-term fertilizer positioning experiment for ten years, four treatments were performed: polymeric-coated controlled-release urea (CRF, 42% N, 3-months controlled-release period), sulfur-coated controlled-release urea (SCF, 35% N, 3-months controlled-release period), common urea (CCF, 46% N) and no nitrogen fertilizer (CK). Results showed that the two coated controlled-release fertilizers significantly increased NUE and dry matter accumulation in summer maize, and ultimately improved grain yield. Compared to CCF, CRF and SCF treatments increased post-silking dry matter accumulation by 16.3% and 13.3%; NUE by 42.3% and 28.9%. The 2-year mean grain yield of CRF and SCF treatment increased 9.0% and 12.4% compared to CCF treatment. CRF treatment significantly increased the NO 3 --N content in 0–60 cm soil layer; while CRF and SCF treatments showed a significantly higher NH 4 +-N concentration in the 0–20 cm soil layer than CCF treatment. Compared to CCF treatment, the CRF and SCF treatments significantly reduced peak ammonia volatilization, and the average cumulative emissions of ammonia volatilization of two years were reduced by 80.8% and 53.2%, respectively. CRF treatment had lower peak of N 2 O emissions but longer N 2 O emission duration than other N application treatments. The two-year average cumulative N 2 O emissions from CRF treatment increased by 49.6%, and SCF treatment increased by 61.1% compared to CCF treatment. Compared to CK treatment, total cumulative CH 4 uptake was 36.1% lower in CRF treatment, 60.9% in SCF and 78.9% in CCF treatment. The higher cumulative N 2 O emissions from CRF and SCF treatment resulted in a significantly higher global warming potential (GWP) than CCF treatment. The two-year mean increase in greenhouse gas intensity (GHGI) was 36.2% for CRF treatment and 44.7% for SCF treatment compared to CCF treatment. Long-term application of coated controlled-release fertilizers could achieve high yields and nitrogen use efficiency. However, there is a risk of increased N 2 O emissions, causing elevated GHGI. In the future, it is necessary to strengthen the research on the comprehensive effects of long-term reduced application of CRU on crop yield and greenhouse gas emissions, in order to promote the wide application of environmentally friendly CRU in the field. [Display omitted] • Long-term application of CRU could achieve sustainable crop yield improvement. • Long-term application of CRU significantly reduced ammonia volatilization and CH 4 emissions. • Long-term application of CRU carried the risk of increased N 2 O emissions, leading to higher GHGI. [ABSTRACT FROM AUTHOR]

• The preferentially dissolved ferrite in pearlite and shedding of cementite lamellae contribute to the formation of corrosion pits. • Corrosion fatigue crack initiation and growth mechanism of U75V rail steel is clarified. • Corrosion fatigue crack initiation behavior is related to morphology ratio and local shape of corrosion pits. Understanding the corrosion fatigue mechanism of rail materials is of great importance to guide the assessment of the structural integrity of modern railway components. To this purpose, the corrosion fatigue crack (CFC) initiation and growth behaviors of heat-treated U75V rail steel are investigated under 3.5 wt% NaCl solution in terms of high-cycle fatigue, fatigue crack growth (FCG) rate, together with surface morphology and microstructure. Experimental results reveal that the U75V rail steel is susceptible to corrosion fatigue failure. Examinations on fractured samples clearly show that the electric potential difference between ferrite and cementite triggers the preferential anodic dissolution of ferrite, leading to corrosion fatigue crack initiation. The crack initiation is not only solely determined by the size of the corrosion pit, but also strongly influenced by its local shape. In comparison with the fatigue crack growth in air, the corrosion FCG tends to grow in a relatively straight path, because of hydrogen embrittlement. Additionally, the CFC behaviors indicate a tendency to transverse through soft-oriented grains and deflect upon encountering hard-oriented grains. [ABSTRACT FROM AUTHOR]

• Fatigue tests are conducted for small specimen and press-fitted axle with defect. • Press-fitted axles exhibit notably lower fatigue strength than small specimens. • Goodman relation is used to consider mean tensile stress induced by press-fitting. • The error of predicted notch fatigue strength is controlled to less than 11%. In order to evaluate the notch fatigue strength of transition groove in railway axle, a series of fatigue tests were conducted on small specimens and press-fitted axles containing surface defects. Based on the experimental and finite element (FE) analyses, a novel method considering mean stress effect was proposed to evaluate the fatigue strength of scale railway axle with surface defect. It is found that press-fitted axles exhibit significantly lower notch fatigue strength than small specimens. Furthermore, the theory of critical distance (TCD) provides a good correlation between the notch fatigue strength of small specimens and experimental results. FE analyses revealed that the press-fitting reduces the fatigue strength of the transition groove through increasing stress concentration and introducing a mean tensile stress that decreases with an increase in the applied loading. To account for the mean stress effect, the axial stress at the groove is corrected as an equivalent stress amplitude at R = -1 based on Goodman relation. Through the combination of TCD and Goodman relation, an estimated fatigue strength with an error of less than 11 % can be achieved for the scale railway axle with surface defect. [ABSTRACT FROM AUTHOR]

Global climate change has significantly increased the frequency and intensity of high temperature and drought stresses. Additionally, the high temperature and drought are often concurred, which make the situation of maize production tougher. However, the influence of the combined stresses of high temperature and drought on summer maize production remains uncertain. The study aimed to investigate the effects of high temperature, drought, and their combined stress at different growth stages on photosynthetic and senescence characteristics of summer maize. Denghai 605 (DH605) was used as the experimental material. High temperature (T), drought (D), and their combined stress (T-D) for 6 days were set at the 3rd leaf stage, 12th leaf stage, and tasseling stage, respectively. The natural temperature and normal water management were used as the control (CK). The results showed that high temperature, drought, and their combined stress at different growth stages decreased the activities of antioxidant enzymes and soluble protein content in leaves, leading to increases in MDA content and damage to cell membranes, which accelerated the senescence of the plant. Accordingly, the activities of RuBPcase and PEPCase were decreased, indicating the abilities of plants to harvest and utilize light energy declined due to high temperature, drought, and combined stresses at different growth stages. As a result, the Pn and thus, the dry matter accumulation rate were decreased by these stresses. In addition, the translocation of dry matter to ears was impeded by stresses, especially by the high temperature at the VT stage. While, high temperatures concurred with drought aggravated the adverse effects on summer maize, compared with single stresses. Significantly, high temperature, drought, and their combined stresses at the VT stage decreased the yield mostly, followed by stresses at the V12 stage, and then by stresses at the V3 stage. Compared with CK, the yield of VT-T-D, V12-T-D, and V3-T-D were decreased by 61.6 %, 13.7 %, and 10.4 %, respectively. As global climate change is unstoppable, the superimposed changes of various meteorological factors make the growth conditions for crop production extreme. Studies to explore the combined effects of two or even more meteorological factors on crop growth are becoming more and more important. This study fulfilled the current knowledge gap of the combined stresses on maize production, however, the underlying mechanisms should be dug out in the future. • High temperature, drought and their combined stress at different growth stages accelerated the senescence of the plant. • Drought concurred with high temperature aggravated the adverse effects on summer maize, compared with single stresses. • Drought concurred with high temperature certainly aggravated the increases of VPD, straining the relationship of CO 2 intakes and water losses. [ABSTRACT FROM AUTHOR]

How to improve nitrogen (N) efficiency and reduce environmental pollution caused by N loss has attracted much attention. However, limited research has lacked a comprehensive exploration of the effects of applying UAN under the micro sprinkling fertigation on reactive N (Nr), fertilizer efficiency and net benefits including environmental costs, plus associated responses of the microbial metagenome. The aim of this study was to assess the impact of N management practices on maize yield, Nr losses, and soil microbial community composition and function. Urea and urea ammonium nitrate solution (UAN) were used as N sources, and three N application rates (210, 168 and 0 kg N ha−1) and two fertilization methods (micro sprinkling fertigation and traditional fertilization) were set as the three key components. The results showed that micro sprinkling fertigation treatments reduced Nr losses, increased yield and N efficiency. Compared with urea, the total NH 3 volatilization and N 2 O emissions of UAN under micro sprinkling fertigation were decreased by 14.8% and 30.6%, respectively. Furthermore, the N reduction (FU1) treatment promoted plant N uptake, was saved 20% of N by affecting soil NH 4 +- N and NO 3 --N content, compared to that of urea, and it regulated the microbial abundance of N cycle function related to denitrification and N respiration, reduced global warming potential and greenhouse gas emission intensity. N application method, N source and N rate affected the diversity and composition of soil bacterial community, and altered Nr emissions by changing the abundance of functional microorganisms related to N cycle. Overall, improved N management practice was more conducive to increasing maize yield and net income, saving N resources, and reducing the risk of environmental damage. Our results contribute to a comprehensive understanding of the impact of N management on summer maize production, providing an effective N management practice that is conducive to "green agricultural development". [Display omitted] • A field trial was conducted in Huang-Huai-Hai Plain of China to clarify N losses and net income. • The soil bacterial community was changed by fertilization methods and N sources. • Applying UAN under micro sprinkling fertigation improved maize yield and saved N resources. [ABSTRACT FROM AUTHOR]

Energy analysis of agricultural production is essential to promote sustainable agricultural development. However, the current research on agricultural sustainability in the North China Plain (NCP) mainly focuses on improving grain yield and nitrogen utilization efficiency (NUE), while there are few studies on their energy utilization. This study evaluated the energy utilization characteristics of different yield and NUE category farms and three integrated agronomic approaches in the NCP based on farmer surveys and farm experiments. Compared with the average level of smallholder farms, the net energy (NE) and the energy utilization efficiency (EUE) of high-yield and high-NUE group farms increased by 17% and 22%, respectively, the NE of the high-yield and low-NUE group farms increased by 9%, but the EUE decreased by 12%. The control experiment showed that the NE and EUE achieved using high-yield and high-efficiency agronomic practice (HH) increased by 34% and 18% compared with achieved using traditional farmers' practices, respectively. In conclusion, there is a great opportunity to improve the NE and EUE of the maize production in the NCP by optimizing agronomic practices. Popularizing HH technology by improving agricultural technology extension services is of great significance for improving farmers' EUE and promoting sustainable agricultural development. • Quantitative analysis of the NE and EUE of maize production systems in the NCP. • Improving the EUE for maize production requires an overhaul of management practices. • Adopting HH production practices could simultaneously improve the NE and the EUE. [ABSTRACT FROM AUTHOR]

The application of nitrogenous fertilizer synergist to coordinate nitrogen transformation process in soil may be an efficient strategy to increase nitrogen use efficiency and decrease environmental pollution. However, there are few reports on the application effects of UAN synergistic nitrification and urease inhibitors under the integration of water and fertilizer. This study aimed to explore effects of urea ammonium nitrate solution (UAN) combined with urease and nitrification inhibitors on yield and nitrogen efficiency of summer maize and its ecological effects under the fertigation, and to provide scientific basis for the efficient utilization of UAN. The experimental treatments were as follows: no inhibitor treatment (U), nitrification inhibitor treatment (U-D), urease inhibitor treatment (U-N), and the combination of nitrification and urease inhibitors treatment (U-D+N). Results showed that UAN combined with urease or nitrification inhibitors could significantly reduce the cumulative emission of N 2 O, and then significantly decreased the N 2 O warming potential (GWP N2O) and N 2 O greenhouse gas intensity (GHGI N2O). Compared with U treatment, the cumulative N 2 O emissions of U-D+N, U-N, and U-D treatments was reduced by 45.7 %, 25.3 % and 35.8 %, respectively. The GWP N2O of U-D+N, U-N and U-D treatments decreased by 45.7 %, 25.3 % and 35.7 %, while GHGI N2O decreased by 50.9 %, 30.3 % and 38.9 % on average, respectively, compared to those of U treatment. Application of urease inhibitors significantly reduced NH 3 volatilization. The cumulative NH 3 volatilization of U-N and U-D+N treatments was reduced by 30.7 % and 23.4 %, while U-D treament was significantly increased by 12.3 %, respectively, compared to that of the U treatment. In addition, UAN combined with urease or nitrification inhibitor could significantly increase the contents of NO 3 --N and NH 4 --N in the 0–20 cm soil layer, and significantly reduced the leaching of NO 3 --N to the deep soil. The total nitrogen accumulation, grain nitrogen content, nitrogen transport efficiency and post-anthesis assimilation of summer maize were significantly increased, which were beneficial to the improvement of grain yield and economic benefits. under the fertigation, the synergistic application of UAN with urease and nitrification inhibitors were beneficial to reduce greenhouse gas emissions and ammonia volatilization, improved the nitrogen use efficiency, and then improved the yield and economic benefits of summer maize. Under the fertigation, UAN combined with urease and nitrification inhibitors were beneficial to emission reduction, high yield, and high efficiency. [Display omitted] • The combination of DCD and NBPT reduced N 2 O and NH 3 emission under fertigation. • The combination of UAN with DCD and NBPT improved N use efficiency under fertigation. • The combination of UAN with DCD and NBPT increased maize yield under fertigation. [ABSTRACT FROM AUTHOR]

In order to improve the grain yield of food crops, which is necessary to ensure food security, it is crucial to narrow existing yield gaps. Quantitative analyses of crop yield gaps can provide theoretical support for ascertaining the primary cause of these yield gaps, and then it can be used to increase the grain yield. We evaluated the size and characteristics of the summer maize yield gap in the North China Plain by combining crop models, farmer surveys, and farm experiments. We simulated the summer maize population of farmers' yield level, attainable yield level and potential yield level by establishing three cultivation modes: traditional farming practices (FP), established high-yield and high-efficiency practices (HH) and super-high-yield practices (SH), and introduce the cultivation relying solely on the basic soil fertility (BSF) to reveal the impact of environmental and management factors on yield gap. We explored the driving factors causing observed variations of yield gaps through a quantitative analysis of several additional parameters that are commonly used to characterize the efficiency of the maize production process, including the contribution rates of dry matter and harvest index to grain yield, the radiation interception rate and the radiation conversion efficiency. Our results show that the total yield gap based on farmer surveys and crop models was 4.9 t ha-1, accounting for 37% of the potential yield, of which 46% was exploitable. The total yield gap based on the farm experiments was 3.9 t ha-1, accounting for 30% of the potential yield, of which 69% was exploitable. The grain yield of FP significantly positively correlated with the grain yield of BSF, HH and SH. The contribution rates of dry matter and harvest index to grain yield of FP treatment were 45.7% and 54.3%, respectively. With the increase of yield level, the contribution rate of dry matter increased and the contribution rate of harvest index decreased. In summary, we found a sizeable total yield gap in summer maize in the North China Plain, and a considerable part is exploitable. Optimizing integrated agronomic management has a great potential for closing the exploitable yield gap. Narrowing the yield gap requires a synergistic increase in the contribution rate of dry matter and harvest index to grain yield, but a substantial increase in dry matter is more important. At present, narrowing the exploitable yield gap requires synergistic improvement of radiation interception rate and radiation conversion efficiency to increase the dry matter of maize population. In the future, the regulation measures aiming at narrowing the unexploitable yield gap should further focus on improving the radiation conversion efficiency. • Quantification of the exploitable and unexploitable yield gaps for maize in the NCP. • Dry matter and harvest index contributions to maize grain formation depend on the yield level. • Suggestions for improving the productivity of established maize farming practices. [ABSTRACT FROM AUTHOR]

In the Huang-Huai-Hai region of China, continuous rain is the main meteorological constraint for summer maize, accompanied by stresses of both waterlogging and shading. To evaluate the independent and combined effects of shading and waterlogging on summer maize at different stages, a field experiment was performed to study the grain yield, crop growth, and canopy functionality of summer maize in response to waterlogging (W), shading (S), and their interaction for a 6 day period starting at the third leaf stage (V3), the sixth leaf stage (V6), and the tasseling stage (VT). Shading, waterlogging, and their combination stress (S+W) significantly decreased the grain yield of summer maize. Among these, the simultaneous stress induced greater yield losses than single stresses at any growth stage. The reduction of yield induced by waterlogging at early and late stages differed from 20–40 % to 3–16 %. Shading at VT stage induced most serious losses of grain yield. The grain yield of summer maize was closely related with the crop biomass accumulation. Shading, waterlogging, and their combination stress significantly decreased leaf area index resulting in serious reduction of the radiation interception. Besides, the leaf SPAD value and photosynthetic rate were also significantly reduced by the stresses, which led to notable reduction in radiation use efficiency (RUE) of summer maize. Thereby, the total accumulated crop biomass was decreased. Moreover, the biomass partitioning to ears was decreased. Accordingly, the 1000-kernel weight and kernels per ear were decreased by the stresses, leading to yield losses. This study explored the differential responses of radiation interception, canopy functionality, and RUE to waterlogging, shading, and their combined stress at different growth stage, furthering our understanding on the yield and growth for summer maize crops under persistent rainfall conditions. • The response of yield components to combined stress at different stage was differed. • Waterlogging at early stage reduced radiation interception and RUE decreasing yield. • Shading at VT lowered incident radiation, decreased kernel setting reducing the yield. • The combined effects of shading and waterlogging on grain yield was greater than single stress. [ABSTRACT FROM AUTHOR]

In the North China Plain (NCP), the deployment of sub-optimal crop management methods has resulted in low maize grain yields and significant environmental costs arising from a low N partial factor productivity (NPFP) and a rampant greenhouse gas emission intensity (GHG i). We hypothesize that in-situ analysis of the grain yield, NPFP and GHG i at local farms might contribute to improving the crop yield, as well as the environmental sustainability of maize production systems. In this study, we investigated the maize production systems deployed at 1574 local farms in the NCP, and quantified the total yield gap (defined as the difference between the yield potential as simulated by the DSSAT-CERES-Maize model and the actual yield achieved by farmers) and the exploitable yield gap (defined as the difference between the attainable yield as calculated by using the Boundary Line Function (BLF) analysis and the average actual yield achieved by farmers). By combining the results from crop modelling, farmer survey data, and on-farm trials, we were able to identify the dominant factors driving the variability in summer maize yield, NPFP, and GHG i. The results revealed that the average grain yield for summer maize in the NCP was 8.3 t ha−1, and that the total and exploitable yield gaps were 4.9 t ha−1 and 3.0 t ha−1, respectively. The average NPFP was 41 kg kg−1, which amounts to 54% of the attainable NPFP. The average GHG i was 463 kg CO 2 eq t−1 grain, which constitutes an increase of 119% over the attainable GHG i. The main factors driving yield include the harvest date and the planting density, and the main factors driving NPFP and GHG i include the N, P and K fertilization rate, where it should be noted that these factors exhibit regional differences. After testing our optimized integrated agronomic management measures in the field experiments, we could confirm that it is possible to narrow the yield gap by 2.7 t ha−1, increase NPFP by 38%, and reduce GHG i by 28%. Obviously, optimizing integrated agronomic management has a great potential for narrowing the yield gap and improving the sustainability of agricultural production. • The total and exploitable yield gaps of maize in the NCP are 4.9 and 3.0 t ha−1. • The main factors driving yield include the harvest date and the planting density. • The N, P and K fertilization rate driving the variability in NPFP and GHG i. • Agronomic optimizations can improve the yield and sustainability of farms in the NCP. [ABSTRACT FROM AUTHOR]

• Effect of artificial notches is studied in terms of fatigue crack non-propagation behaviors. • Non-propagation crack rate firstly increases and then decreases with the increased notch depth. • Gradient residual stress and microstructure are responsible for the crack non-propagation. • Crack traces of post-mortem specimen in the hardened layer and the matrix are compared. Abnormal damages in railway axles can lead to a significant hazard to running safety and reliability. To this end, a surface treatment was selected to effectively inhibit fatigue crack initiation and growth. In this study, a single-edge notch bending fatigue test campaign with artificial notches was conducted to elucidate the fatigue crack non-propagation behavior in railway S38C axles subjected to an induction hardening process. The fatigue cracking behavior in the gradient structure was revealed by optical microscopy, electron backscatter diffraction, and fractography. The microhardness distribution was measured using a Vickers tester. The obtained results show that the microhardness of the strengthening layer is nearly triple that of the matrix. Owing to the gradient microstructures and hardness, as well as compressive residual stress, the fatigue long crack propagates faster once it passes through the hardened zone (approximately 2.0 mm in the radial depth). Thereafter, local retarding (including deflection, branching, and blunting) of the long crack occurs because of the relatively coarse ferrite and pearlite in the transition region and matrix. Totally, this fatigue cracking resistance is reasonably believed to be due to the gradient microstructure and residual stress. These findings help to tailor a suitable detection strategy for maximum defects or cracks in railway axles. [ABSTRACT FROM AUTHOR]

The maize production sector in the North China Plain (NCP) is facing the dual pressures of having to increase its grain yield and improve its environmental sustainability. Evaluating the yield gap and ascertaining the factors that limit the grain yield might suggest new approaches to address these challenges. The objective of this study was to estimate the yield potential and the yield gap associated with smallholdings in the NCP using a hybrid method; to determine the factors driving the grain yield and corresponding sustainability indicators; and to evaluate to what degree the introduction of scientifically developed high-yield and high-efficiency agronomic practices (HH) to smallholders might help to sustainably narrow the exploitable yield gap. Combined with diagnostic smallholder survey and crop modeling exercise to characterize and decompose yield gaps. With survey data, we assessed the existing variation with respect to various key performance indicators and carried out a number of controlled comparative experiments at farms (HH vs traditional farming practices (FP)) in multiple locations. Our work revealed the total and exploitable yield gap were 4.3 t ha−1 and 1.8 t ha−1 for rainfed summer maize, and 4.4 t ha−1 and 1.9 t ha−1 for irrigated summer maize across the entire NCP, indicating a large potential for yield improvements. The main factors driving the yield from the entire region were the planting density, the fertilization frequency, and the irrigation frequency. It should be noted that farmers whose yield was in the top 25% bracket of the yield distribution also achieved relatively high utilization efficiencies with respect to N, P, and K fertilizers (15%, 16%, and 16% above the average values, respectively) while their profit was 41% above average. Comparative experiments conducted over several seasons support insights from surveys by demonstrating that major gains in grain yield (+30%), the fertilizer utilization efficiency (+37% in N partial factor productivity, +48% in P partial factor productivity, and + 32% in K partial factor productivity) and economic profit (+62%) are achievable through the adoption of HH. Through a hybrid method, our results suggest that agricultural intensification can be achieved in the NCP without having to trade off yield against environmental sustainability. Evidently, smallholders can simultaneously improve their maize grain yield, fertilizer utilization efficiency, and profit by adopting straightforward non-disruptive optimizations of their agronomic practices. [Display omitted] • Mixed-method approach used to decompose maize yield gaps with crop model, diagnostic smallholder surveys, and controlled comparative experiments. • We found a sizeable total yield gap (4.3 and 4.4 t ha−1 for rainfed and irrigated maize) in the NCP, of which 1.8 and 1.9 t ha−1 is exploitable. • Main factors driving yield include the planting density, the N topdressing frequency, and the irrigation frequency. • High-yield farms had greater N, P and K fertilizer use efficiencies and increased economic profit. • Smallholder production could be improved by optimize agronomic practices and without having to trade off yield against environmental sustainability. [ABSTRACT FROM AUTHOR]

BACH1 (Brca1-Associated C-terminal Helicase) is an important DNA damage response factor, which is involved in DNA damage repair and maintenance of genomic stability. In this study, by using tandem protein affinity purification, we have identified BCLAF1 as a novel functional partner of BACH1. BCLAF1 constitutively interacts with BACH1 regardless of DNA damage. However, in response to DNA damage, along with BACH1, BCLAF1 is recruited to the DNA damage sites and the recruitment of BCLAF1 was regulated by BACH1 and BRCA1. Interestingly, BCLAF1 deficient cells are deficient for DSB-initiated HR, but RAD51 foci formation is intact following IR treatment. Taken together, these findings reveal that BCLAF1 is a functional binding partner of BACH1 playing a key role in DNA damage response. • BCLAF1 associates with BACHI and is involved in homologous recombination repair. • BCLAF1 BACH1 is required for targeting BCLAF1 to DNA damage sites. • BCLAF1 is involved in homologous recombination. [ABSTRACT FROM AUTHOR]

Optimizing the canopy nitrogen (N) distribution by matching the available light resources to construct a light-N matching canopy structure of summer maize is important to improve yield and narrow the yield gap (YG). A field experiment with four integrated agronomic management practice systems [a control treatment (T1), an improved management system (T2), a super high-yield management system (T3), and an optimized management system (T4)] was conducted at Da Wenkou Town, Tai'an, China, from June to October in -2018–2020 to study the canopy light and N distribution and photosynthetic N use efficiency of summer maize. The results showed that optimized integrated agronomic management practices could coordinate canopy light and N distributions to increase the yield, thus narrowing the YG between T1 and yield potential by 1.9–5.2 Mg ha-1. In addition, the T4 treatment intercepted more radiation by adjusting the leaf area. Furthermore, the leaf N content of T4 in the middle canopy was significantly increased. The coordination of canopy light and N distributions of T4 was increased significantly, which was conducive to maximizing the use of N and solar radiation and increasing photosynthetic N use efficiency significantly by 9.4–41.4%, compared to that of T1. As a result, the yield of T4 was increased by 37.0% compared to that of T1. And T4 narrowed the YG by 3.4 Mg ha-1. Therefore, the T4 was the best choice for achieving a high-yield and high-efficiency production of summer maize in this study. • Optimized agronomic management improved leaf nitrogen vertical distribution. • Optimized agronomic management increased canopy light interception. • Optimized agronomic management narrowed yield gap by regulating canopy structure. [ABSTRACT FROM AUTHOR]

• Surface rolling deformed severity-dependent fatigue mechanism of titanium alloy was revealed. • The microstructural evolutions of the samples with different surface rolling deformation severities during fatigue loading were revealed. • The residual stress evolutions during fatigue loading for the different surface rolling deformed samples were clarified. • A surface strengthening strategy was given to enhance the stress-controlled fatigue property of titanium alloy. This work investigates the effect of initial surface plastic deformation on the fatigue behavior of Ti-6Al-4V alloy based on the microstructure and residual stress evolution under fatigue loading. The high strain hardening ability, full play of compressive residual stress, and excellent surface integrity of samples with low plastic deformation severity resulted in relatively higher fatigue strength. Microstructural analysis revealed that the ultrasonic surface rolling process (USRP) applied to samples with low plastic deformation severity accommodated plastic strain by refining the grains, whereas the grains coarsened in the USRP samples with high plastic deformation severity for accommodating the plastic strain. [ABSTRACT FROM AUTHOR]

The experiment is to explore the efficient and comprehensive utilization of maize straw resources to achieve the sustainability of the soil fertility under double cropping of winter wheat and summer maize. Summer maize hybrid Denghai 605 (DH605) and winter wheat variety Tainong 18 (TN18) were used as experimental materials. Based on all winter wheat straw returned to the field, the treatment of all summer maize straw (SR) and half of summer maize straw (1/2SR) and summer maize straw not returned to the field (CK) 3 experimental treatments were tested for 8 consecutive years. Under the condition of normal nitrogen application of 210 kg ha−1, two split areas were set to reduce the amount of nitrogen fertilizer by 15% and 30% (SR-15%、SR-30%、1/2SR-15%、1/2SR-30%、CK-15%、CK-30%) at the beginning of the 2016 wheat season. In the first two years of reduced nitrogen application, the yields of SR and 1/2SR treatments were significantly higher than that of CK under the same nitrogen application conditions, while the yields of SR, 1/2SR, SR-15%, and 1/2SR-15% were not significantly different. In the third year of the process of reducing nitrogen fertilizer, compared with SR, 1/2SR, and SR-15% treatments, the yield of 1/2SR-15% were significantly reduced by 9% under winter wheat season. During winter wheat and summer maize season, the nitrogen use efficiency, and nitrogen absorption efficiency of SR and 1/2SR were significantly increased compared with CK treatment under the same nitrogen rate, of which SR-15% treatment was not significantly different from SR and 1/2SR. The pre-anthesis nitrogen transfer rate and nitrogen harvest index of summer maize treated with SR, 1/2SR, SR-15% and 1/2SR-15% were also significantly increased, compared with CK and CK-15% treatments. The win-win situation of ecological and crop yield can be achieved by return half of the straw to the field or reducing the nitrogen fertilizer application by 15% under the condition of straw returned to the field. • Returning the full amount of summer corn to the field can stably replace 15% of the nitrogen fertilizer application. • The yield stability and NUE of SR-15% treatment are not significantly different between with SR and 1/2 SR treatments. • The 1/2SR treatment can achieve a synergistic increase in crop yield and nitrogen utilization under NCP in China. [ABSTRACT FROM AUTHOR]

Root growth demonstrates a high degree of plasticity in response to spatial variations in the availability of vital nutrients, and P fertilizer placement depth affects the development and distribution of plant roots. Optimizing the spatial matching between soil nutrients and the roots of maize plants in order to improve their N and P uptake and utilization capacity is a potential measure for improving the grain yield from summer maize. The spatial distribution profile of N, P and roots in the soil, as well as the roots' absorption and utilization characteristics with respect to N and P and how these relate to the dry matter accumulation and grain yield formation were evaluated under four different placement depths of 5, 10, 15 and 20 cm (labeled P 5 , P 10 , P 15 , and P 20 , respectively). Compared with the P 5 treatment, the P 15 treatment induced a larger root length density, as well as a larger rooting depth. That happened because a higher number of root cortical aerenchyma, combined with a larger cortical cell size, reduces the metabolic cost required to establish them, which drives regulation processes that result in the allocation of more biomass to root proliferation. It also helped plants to maintain a higher level of biomass and N and P accumulation during the later growth period, which in turn increased the N and P assimilation of grain and enhanced the grain yield by 22%, the P recovery efficiency by 74%, the P agronomic efficiency by 150%, and both the partial factor productivity of P and the partial factor productivity of N by 21%. In conclusion, this study demonstrates that placing P fertilizer at a depth of 15 cm promotes root growth by reducing the metabolic cost of having a higher number of root cortical aerenchyma and a larger cortical cell size, and also that it improves the N and P absorption and utilization of roots and synergistically increases the grain yield and nutrient utilization efficiency of the whole plant. • Moderate deep P fertilization improved the matching degree of root and nutrient. • The optimization of root anatomical structure reduced its metabolic cost. • Grain yield and nutrient use efficiency were both improved by deep P fertilization. [ABSTRACT FROM AUTHOR]

• Waterlogging-induced damages on summer maize were related with phosphorus signals. • Application of 6-BA effectively improved the operation of photosynthetic apparatus in waterlogged summer maize by affecting the cytokinin-induced phosphorus signals. • Application of 6-BA in agricultural practices provides new insights into curbing adverse climate change-related effects on crop production. Summer maize suffers severe yield losses due to waterlogging, threatening food security. Application of 6-benzyladenine (6-BA) can modify protein phosphorylation status, and increase plant tolerance to waterlogging. However, little is known regarding the functional roles of 6-BA-mediated phosphorylation events in regulating plant stress tolerance. Therefore, we conducted an experiment involving three treatments (control (CK), waterlogging at the third leaf stage for 6 days (V3−6), and application of 100 mg L−1 6-BA after waterlogging (V3−6-B)) to probe the impact of 6-BA on leaf phosphoproteome of waterlogged summer maize. Our results demonstrated that waterlogging affected the reversible phosphorylation of proteins that participated in chloroplast movement and differentiation as well as photoreaction and carbon fixation processes. However, application of 6-BA significantly mitigated the waterlogging effects on the phosphorylation level of these proteins. Accordingly, the chloroplast ultrastructure and photosynthetic performances of waterlogged summer maize were improved. These results indicated that application of 6-BA mediated extensive phosphorylation events to improve the absorption and dissipation of light energy, the assimilation and metabolism of carbon, and the ultrastructure of chloroplast, thus increasing the photosynthesis rate of waterlogged summer maize. consequently, the plant growth and grain yield of waterlogged summer maize were improved by application of 6-BA. [ABSTRACT FROM AUTHOR]

• A moderate nitrogen rate ensures appropriate nitrogen content in leaves. • An appropriate nitrogen content in leaves affects grain yield formation by adjusting spike differentiation. • The leaf-N status influences spike differentiation through N accumulation and transport. Spike differentiation plays a pivotal role in maize (Zea mays L.) yield formation. However, it is unclear if leaf-N status affects yield formation by modifying spike differentiation. To understand how the spike differentiation is affected by leaf N content, as affected by the N rate, a field experiment was conducted. The experiment consisted of four N rates: N0 (0 kg N ha–1), N1 (129 kg N ha1), N2 (184.5 kg N ha−1), and N3 (300 kg N ha−1). At zero (N0) or low (N1) N rate, N stress significantly reduced the leaf N content of summer maize, which in turn reduced the N accumulation and N transfer from leaves to spike during spike differentiation, compared to the moderate N rate (N2), especially at the tassel-floret and ear-spikelet differentiation stage (FT-SE). So the reproductive growth was delayed by 2–4 days under N0 and N1, abortive florets of the ear were increased by 28.2–166.2 %, and the anthesis-silking interval was lengthened by 2–4 days, compared with N2, which reduced the kernel set and subsequently the silk and grain number per ear. Appropriate N rate (N2) could increase N metabolism-related enzymatic activities and increase the content of glutamine (Gln) and asparagine (Asn) in leaves, which in turn increased N transfer to spike to promote spike differentiation and decrease abortive florets. Finally, the silk and kernel set under N2 were increased, which resulted in an increased in grain number per ear and yield by 3.5–27.4 % and 13.1–41.8 %, respectively, compared with N0 or N1. However, the excessive N rate (N3) demonstrated a threshold, which no longer promoted spike differentiation. Moreover, leaves had an N-absorption peak at the FT-SE, and the N content positively correlated with the total numbers of silks and florets per ear. The efficient absorption of N at the FT-SE was beneficial to increase floret fertility. Collectively, a moderate N fertilizer rate (around 185 kg N ha−1) assured appropriate N accumulation in leaves and N transfer to spike, improved spike development and increased floret fertility, grain number and yield. [ABSTRACT FROM AUTHOR]