A growing global demand exists to formulate plans to lessen the greenhouse gas emissions produced by agricultural activities.The purpose of this study was to uncovered the changes in soil CO_(2)fluxes under varying sc...A growing global demand exists to formulate plans to lessen the greenhouse gas emissions produced by agricultural activities.The purpose of this study was to uncovered the changes in soil CO_(2)fluxes under varying scenarios including nitrogen fertilization rates,irrigation rates,and air temperatures in the Hetao Irrigation District(HID)over the 38-year period.DAYCENT model was used to predict carbon dioxide(CO_(2))fluxes from cultivated soils in the HID,Inner Mongolia from^(2)023 to 2060(the year of achieving the"carbon neutrality"goal)in this study.Results showed that mean soil CO_(2)fluxes in the sunflower field[1035.13 g/(m^(2).yr)]were significantly lower than those in the maize field[1405.54 g/(m^(2).yr)].An increase in nitrogen fertilization rate led to a significant escalation in soil CO_(2)fluxes.Moreover,elevating irrigation rates for washing salts by irrigation(WSBI)diminished soil CO_(2)fluxes in the sunflower field while amplifying them in the maize field.A rise in air temperature resulted in an increase in soil CO_(2)fluxes from the maize field,with annual increases observed,but a reduction in soil CO_(2)fluxes from the sunflower field.The sunflower fields in the HID have a more substantial advantage than the corn fields in mitigating soil CO_(2)emissions.展开更多
Long-term straw return with appropriate nitrogen(N)fertilization increases seedcotton yield and fiber quality,and the root system plays an important role in cotton production.However,under straw return and N fertiliza...Long-term straw return with appropriate nitrogen(N)fertilization increases seedcotton yield and fiber quality,and the root system plays an important role in cotton production.However,under straw return and N fertilization,the relationship between the cotton boll-loading capacity of the root system and seedcotton yield remains unclear.In this study,a ten years of long-term field experiment was conducted in a wheat-cotton rotation system.The effects of straw treatments(straw return and straw removal)and N rates(N0,N75,N150 and N300 representing 0,75,150 and 300 kg N ha^(-1),respectively)on cotton root activity,boll-loading capacity of the root system and their relationship to seedcotton yield from 2019 to 2022 were quantified.The results showed that straw return with an appropriate N fertilization of N150 increased root biomass,the rate and components of root-bleeding sap,as well as boll-loading capacity of the root system and seedcotton yield,but decreased the ratio of root to shoot biomass.Furthermore,the root-bleeding sap rate reached the maximum at 30 d post anthesis(DPA)during the peak boll setting stage.However,the contents of nitrate-N,free amino acids and soluble sugar in root-bleeding sap decreased from 10 DPA.Notably,in 2021 and at 30 DPA,the highest contents of nitrate-N(4.8μg mL^(-1))and free amino acids(8.3μg mL^(-1)),as well as soluble sugar(3.4μg mL^(-1))were observed at N150 under straw return.The increase in seedcotton yield is positively correlated to the soluble sugar content.Straw return significantly increased the boll-loading capacity of the root system,which first increased but then decreased with the increase in N fertilization.Under straw return with N150,the maximum seecotton yield(3455-4544 kg ha^(-1))was recorded,and the largest boll loading(49-54 boll 100 g^(-1))and boll capacity(242-292 g 100 g^(-1))of root system at the boll opening stage were observed.Therefore,straw return with appropriate N fertilization improved root activity and the boll-loading capacity of the root system,thereby increasing seedcotton yield.This study provides new insights into improving seedcotton yield from the perspective of coordinating cotton growth.展开更多
Regulating planting density and nitrogen(N)fertilization could delay chlorophyll(Chl)degradation and leaf senescence in maize cultivars.This study measured changes in ear leaf green area(GLA_(ear)),Chl content,the act...Regulating planting density and nitrogen(N)fertilization could delay chlorophyll(Chl)degradation and leaf senescence in maize cultivars.This study measured changes in ear leaf green area(GLA_(ear)),Chl content,the activities of Chl a-degrading enzymes after silking,and the post-silking dry matter accumulation and grain yield under multiple planting densities and N fertilization rates.The dynamic change of GLA_(ear)after silking fitted to the logistic model,and the GLA_(ear) duration and the GLAearat 42 d after silking were affected mainly by the duration of the initial senescence period(T_(1))which was a key factor of the leaf senescence.The average chlorophyllase(CLH)activity was 8.3 times higher than pheophytinase activity and contributed most to the Chl content,indicating that CLH is a key enzyme for degrading Chl a in maize.Increasing density increased the CLH activity and decreased the Chl content,T1,GLAear,and GLA_(ear) duration.Under high density,appropriate N application reduced CLH activity,increased Chl content,prolonged T1,alleviated high-density-induced leaf senescence,and increased post-silking dry matter accumulation and grain yield.展开更多
This experiment was conducted in Xinxiang, Henan from June 2013 to June 2014. Total four treatments were designed including farmers ’ common practice （F, 250 kg/hm^2）, 80% F （LF, 200 kg/hm^2）, 80% F＋biochar （LF...This experiment was conducted in Xinxiang, Henan from June 2013 to June 2014. Total four treatments were designed including farmers ’ common practice （F, 250 kg/hm^2）, 80% F （LF, 200 kg/hm^2）, 80% F＋biochar （LFC） and no fertilizer （CK） to measure the dynamic emissions of CO2 and N2O from a summer maize-winter wheat field by static chamber-gas chromatography method. The results showed that the soil CO2 emission was 21.8-1 022.7 mg/（m^2·h）, and was mainly influenced by soil temperature and moisture content. During the growth of summer maize, the soil CO2 emission was more significantly affected by soil moisture con-tent; and in winter wheat growing season, it was more significantly affected by soil temperature in the top 5 cm. The LF and LFC treatments significantly reduced the soil cumulative CO2 emission, especial y during the growth of winter wheat. Fertiliza-tion and irrigation were the main factors influencing the soil N2O emission. The soil N2O emission during the fertilization period accounted for 73.9%-74.5% and 40.5%-43.6% of the soil cumulative N2O emission during the summer maize-and winter wheat-growing season, respectively. The peak of emission fluxes was determined by fertilization amount, while the occurrence time of emission peak and emission re-duction effect were influenced by irrigation. The LF treatment reduced the soil cu-mulative N2O emission by 15.7%-16.8% and 18.1%-18.5% during the growth period of summer maize and winter wheat, respectively. Reduced nitrogen fertilization is an effective way for reducing N2O emission in intensive high-yielding farmland. Under a suitable nitrogen level （200 kg/hm^2）, the application of biochar showed no significant effect on the soil N2O emission in a short term. The N2O emission factors of the L and LF treatments were 0.60% and 0.56%, respectively. ln the intensive high-yield-ing farmland of North China, reducing the nitrogen application amount is an appro-priate measure to mitigate greenhouse gas emissions without crop yield loss.展开更多
Under the condition of reduced application of nitrogen fertilizer, the impact of silicor）, zinc and boron on rice growth was investigated by field experiment. The results showed that when the application amount of ni...Under the condition of reduced application of nitrogen fertilizer, the impact of silicor）, zinc and boron on rice growth was investigated by field experiment. The results showed that when the application amount of nitrogen fertilizer was reduced by 20%, the application of silicon, zinc and boron did not reduce the yield of rice, but reduced the incidence of panicle blast in rice and optimized the structure of rice production.展开更多
A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs.This study was designed to determine whether optimized nitrogen(N)fertilization coul...A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs.This study was designed to determine whether optimized nitrogen(N)fertilization could fulfill these multiple goals.In two-year experiments,two high yielding‘super’rice cultivars were grown with different N fertilization management regimes,including zero N input,local farmers’practice(LFP)with heavy N inputs,and optimized N fertilization(ONF).In ONF,by reducing N input,increasing planting density,and optimizing the ratio of urea application at different stages,N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels.Compared with LFP,yield and partial factor productivity of applied N(PFP)under ONF were increased(on average)by 1.70 and 13.06%,respectively.ONF increased starch and amylose content,and significantly decreased protein content.The contents of the short chains of A chain(degree of polymerization(DP)6-12)and B1 chain(DP 13-25)of amylopectin were significantly increased under ONF,which resulted in a decrease in the stability of rice starch crystals.ONF increased viscosity values and improved the thermodynamic properties of starch,which resulted in better eating and cooking quality of the rice.Thus,ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency(NUE)at high yield levels.These results will be useful for applications of high quality rice production at high yield levels.展开更多
Grain filling, a crucial stage of grain yield formation in rice, is usually affected by the panicle nitrogen （N） fertilization. Field and pot culture experiments were conducted to explore the underlying mechanisms o...Grain filling, a crucial stage of grain yield formation in rice, is usually affected by the panicle nitrogen （N） fertilization. Field and pot culture experiments were conducted to explore the underlying mechanisms of N effect. Two rice cultivars with high lodging resistance were grown in the field and pot. Four panicle N fertilization treatments were conducted in 2006 and repeated in 2007. The result showed that medium level of panicle N fertilization treatment （NM） enhanced the accumulation and translocation of non-structural carbohydrate （NSC） in the stem and sheath. Compared with non-nitrogen treatment （NO）, NM promoted the translocation of labeled ^13C from stem and sheath to grain. But, low level of panicle N fertilization treatment （NL） and high level of panicle N fertilization treatment （NH） showed the negative effect. The endosperm cell, grain length, and grain width of NM increased more quickly than that of NO from 4 to 10 d after anthesis. During the early period of grain filling, sucrose-phosphate synthase （EC 2.4.1.14, SPS） activity were significantly higher for the NM treatment than those of the NL and NH treatments. Sucrose synthase （EC 2.4.1.13, SuSase） activity in the grains was substantially enhanced by NM, with the duration of higher activity being longer than those of the other treatments. At maturing stage, NM significantly increased the filled grain number, the seed-setting rate, and the grain weight compared with NL and NH. The results suggest that NM have a positive effect on the activities of enzymes of physiological importance, thereby increasing the grain size and promoting grain filling.展开更多
By analyzing and extracting the research progress on nitrogen fertilization in wheat, a dynamic knowledge model for management decision-making on total nitrogen rate, ratios of organic to inorganic and of basal to dre...By analyzing and extracting the research progress on nitrogen fertilization in wheat, a dynamic knowledge model for management decision-making on total nitrogen rate, ratios of organic to inorganic and of basal to dressing nitrogen under different environments and cultivars in wheat was developed with principle of nutrient balance and by integrating the quantitative effects of grain yield and quality targets, soil characters, variety traits and water management levels. Case studies on the nitrogen fertilization model with the data sets of different eco-sites, cultivars, soil fertility levels, grain yield and quality targets and water management levels indicate a good performance of the model system in decision-making and wide applicability.展开更多
Degraded soil aggregation arising from nitrogen(N)fertilization has been reported in many studies;however,the mechanisms have not yet been clarified.Elucidating the impact of N fertilization on soil aggregation would ...Degraded soil aggregation arising from nitrogen(N)fertilization has been reported in many studies;however,the mechanisms have not yet been clarified.Elucidating the impact of N fertilization on soil aggregation would help to improve soil structure and sustain high crop production.The objective of this study was to determine the impact of long-term N fertilization on soil aggregation and its association with binding and dispersing agents.A 12-year(2008–2019)N fertilization field experiment on a Vertisol was performed,covering a wide range of N application rates(0,360,450,540,630,and 720 kg ha-1 year-1)and including straw management(straw return and straw removal)in a wheat(Triticum aestivum L.)-maize(Zea mays L.)cropping system.Soil samples of 0–20 cm depth were collected from 12 field treatments with 3 replications in 2019.Soil aggregate stability(mean weight diameter(MWD))and contents of soil organic carbon(SOC),glomalin-related soil protein(GRSP),microbial biomass carbon(MBC),and mineral N(NH4+and NO3-)were determined.Long-term N fertilization under straw removal conditions reduced soil MWD by 12%–18%at N rates from 0 to 720 kg ha-1 compared to that under straw return(P<0.05).Soil MWD was positively associated with pH(P<0.05)and MBC(P<0.05),but negatively correlated with NH4+(P<0.05)and NO3-(P<0.05).Compared with the straw removal treatment,the straw incorporation treatment significantly improved the contents of aggregating agents(SOC,GRSP,and MBC)(P<0.001),but did not affect that of the dispersing agent(NH4+)(P>0.05);consequently,it improved soil aggregation.Overall,our results indicate that long-term N fertilization may degrade soil aggregation because of the increases in monovalent ions(H+and NH4+)and the decrease in MBC during soil acidification,especially when the applied N dose exceeded 360 kg ha-1 year-1.Our finding can minimize the negative structural impacts on Vertisol.展开更多
Minimizing soil ammonia（NH_3） and nitrous oxide（N_2O） emission factors（EFs） has significant implications in regional air quality and greenhouse gas（GHG） emissions besides nitrogen（N） nutrient loss.The aim of...Minimizing soil ammonia（NH_3） and nitrous oxide（N_2O） emission factors（EFs） has significant implications in regional air quality and greenhouse gas（GHG） emissions besides nitrogen（N） nutrient loss.The aim of this study was to investigate the impacts of different N fertilizer treatments of conventional urea,polymer-coated urea,ammonia sulfate,urease inhibitor（NBPT,N-（n-butyl） thiophosphoric triamide）-treated urea,and nitrification inhibitor（DCD,dicyandiamide）-treated urea on emissions of NH_3 and GHGs from subtropical wheat cultivation.A field study was established in a Cancienne silt loam soil.During growth season,NH_3 emission following N fertilization was characterized using active chamber method whereas GHG emissions of N_2O,carbon dioxide（CO_2）,and methane（CH_4） were by passive chamber method.The results showed that coated urea exhibited the largest reduction（49%） in the EF of NH_3-N followed by NBPT-treated urea（39%） and DCD-treated urea（24%） over conventional urea,whereas DCD-treated urea had the greatest suppression on N_2O-N（87%） followed by coated urea（76%） and NBPT-treated urea（69%）.Split fertilization of ammonium sulfate-urea significantly lowered both NH_3-N and N_2O-N EF values but split urea treatment had no impact over one-time application of urea.Both NBPT and DCD-treated urea treatments lowered CO_2-C flux but had no effect on CH_4-C flux.Overall,application of coated urea or urea with NPBT or DCD could be used as a mitigation strategy for reducing NH_3 and N_2O emissions in subtropical wheat production in Southern USA.展开更多
The experiment was conducted in the abandoned land of Liangjia Village,Huayin City,Shaanxi Province from April to September 2019.The experimental crop was spring maize.A total of six treatments were set up in a random...The experiment was conducted in the abandoned land of Liangjia Village,Huayin City,Shaanxi Province from April to September 2019.The experimental crop was spring maize.A total of six treatments were set up in a randomized block design.The moisture content of the top 0-60 cm soil was determined regularly,and the yield and quality indices of maize at maturity were checked.The results show that:(i)combined organic-inorganic fertilization increased the yield of spring maize by 3%-8%.(ii)Compared with CK,fertilization treatments significantly improved the water use efficiency of spring maize,with an increase of 59.2%.The average water use efficiency of three combined organic-inorganic fertilization treatments was 27.81 kg/(ha·mm).Compared with CON,combined application of organic and inorganic fertilizers significantly improved the water use efficiency of spring maize,with an increase of 12.5%.(iii)The combined application of organic and inorganic fertilizers increased the moisture,total starch,crude protein and crude fat contents,and reduced crude fiber content of maize kernels.However,with the increase of the proportion of organic fertilizer,the crude protein content of maize kernels decreased.(iv)Yield of spring maize showed a significant parabolic relationship with soil water consumption.In summary,70%inorganic fertilizer+30%organic fertilizer is a scientific and reasonable way of fertilization.展开更多
High nitrogen （N） input features China＇s intensive rice production system. To elucidate N and genotype effects on accumulation of macronutrients and micronutrients in grains of japonica rice, and to discuss its sig...High nitrogen （N） input features China＇s intensive rice production system. To elucidate N and genotype effects on accumulation of macronutrients and micronutrients in grains of japonica rice, and to discuss its significance in rice production, a three-year field experiment involving six japonica rice varieties and seven N treatments were performed. Macronutrients （Ca, Mg, K, and Na） and micronutrients （Cu, Fe, Mn, and Zn） concentrations in brown and milled rice were measured using an atomic absorption spectrophotometer. For macronutrients, no consistently significant effect of N was detected in both brown and milled rice. For micronutrients, N showed significant effect, especially in lowering Zn accumulation in brown and milled rice. In addition, N tended to increase Fe concentration in milled rice. Genotype showed larger effect on distribution of minerals in milled rice than N. The high-yielding variety, Wuyunjing 7, accumulated larger proportion of Mg, K, and Zn in the milled rice as compared with the other five varieties and could be of value for rice breeding programs aiming at high nutritional quality. The results demonstrated differences in response to N between macronutrients and micronutrients, and are of significance for coping with ＇hidden hunger＇ both in humans and crops through agronomical practices.展开更多
[Objective] This study aimed to provide certain scientific basis for reasonable application of nitrogen fertilizer in the pollution-free cultivation of Phaseolus vulgaris. [Method] A field experiment was conducted to ...[Objective] This study aimed to provide certain scientific basis for reasonable application of nitrogen fertilizer in the pollution-free cultivation of Phaseolus vulgaris. [Method] A field experiment was conducted to investigate the effects of different nitrogen fertilization amounts on the prophase yield and economic efficiency of P. vulgaris and available nitrogen content of soil. [Result] With the increased application amount of nitrogen fertilizer, the prophase yield and economic efficiency of P. vulgaris reached the peaks in the Treatment 3 （8 690.48 kg/ hm^2 and 32 222 yuan/hm^2）, and significant differences were found among different treatment groups. With the increased nitrogen fertilization amount, the soil available nitrogen content increased, showing a positive correlation with correlation coefficient of 0.856 5. Excess nitrogen fertilizer reduced the prophase yield and economic efficiency of P. vulgaris. For the open field cultivation of P. vulgaris, the optimum application amount of nitrogen fertilizer was 178 kg/hm^2. [Conclusion] Application of nitrogen fertilizer could effectively increase the soil available nitrogen content.展开更多
Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultiv...Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consumed by some field practices, such as stubble return and coupled water and nutrient management, soil pH would maintain relatively stable if proper management practices can be adopted in this region.展开更多
The effect of nitrogen fertilization on leaf chlorophyll fluorescence was studied in field-grown winter wheat during grain filling underrainfed conditions in Loess Plateau. Results showed that the actual photochemical...The effect of nitrogen fertilization on leaf chlorophyll fluorescence was studied in field-grown winter wheat during grain filling underrainfed conditions in Loess Plateau. Results showed that the actual photochemical efficiency of PSⅡ reaction center (F PSⅡ)decreased significantly as leaf water stress progressed, however, the F PS was increased by nitrogen fertilization. The F PSⅡ of 0, 90 and180 kg ha-1 nitrogen treatments at noon were 0.197, 0.279 and 0.283, respectively, which decreased by 57.7, 56.4 and 40.2% as comparedto those in the morning. In the afternoon, the F PSⅡ partialy or completely recovered to the levels in the morning. The values of F PS Ⅱin 0 and 90kgha-1 treatments recovered to 87.3 and 81.5% of those in the morning. In 180kgha-1 treatment, the F PSⅡ in the afternoonwas even higher than that in the morning. Application of nitrogen fertilizer significantly increased maximum photochemical efficiency(Fv/Fm), photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (qNP). These results indicated thatapplication of nitrogen fertilizer could increase the light energy conversion efficiency, the potential activity of photosynthetic reactioncenter, and the non-photochemical dissipation of excess light energy, which can prevent leaf photosynthetic apparatus from damage ofenvironmental stress. However, there was no significant difference in the values of F PSⅡbetween 90 and 180kgha-1 nitrogentreatments, indicating that the excess nitrogen was unfavorable to photosynthesis.展开更多
Widespread soil acidification driven by nitrogen(N)fertilization and precipitation challenges the conventional notion of the long-term stability of soil inorganic carbon(SIC)in agroecosystems.However,the changes in SI...Widespread soil acidification driven by nitrogen(N)fertilization and precipitation challenges the conventional notion of the long-term stability of soil inorganic carbon(SIC)in agroecosystems.However,the changes in SIC with precipitation and N fertilization remain ambiguous.Based on 4,000+soil samples collected in the 1980s and 2010s and by developing machine learning models to fill the missing SIC of soil samples,this study generated 3,697 paired soil samples between the two periods and then investigated the cropland SIC change and explored its relationship with precipitation and N fertilization across the Sichuan Basin,China.The results showed an overall SIC loss,with a decline of the mean SIC by 15.73%.SIC change varied with initial soil pH and initial SIC and exhibited an exponential relationship with soil pH change,indicating the changing role of carbonates in providing acid-buffering capacity.There was a parabolical relationship between the magnitude of SIC decline and N fertilizer rates,and low N fertilizer rates contributed to a reduction in SIC loss,while SIC loss was promoted by N fertilization occurred when N fertilizing rates exceeded 250 kg ha^(-1) yr^(-1).The change in SIC showed a sinusoidal variation with precipitation,with 950 mm being the threshold controlling whether SIC increased or decreased.Meanwhile,N fertilization did not alter the sinusoidal relationship between SIC change and precipitation.In areas with rainfall<950 mm,the high N fertilizer rate did not cause SIC loss,while higher precipitation could also cause larger SIC loss in areas with lower N fertilizer rates.These results suggest that SIC dynamics are jointly driven by precipitation and N fertilization and are controlled by acid-buffering mechanisms associated with initial pH and SIC,with precipitation being the predominant driver.These findings emphasize the need for more regional soil observations and in-depth studies of SIC change and its mechanisms for accurately estimating SIC change.展开更多
The yield of maize(Zea mays L.)is highly influenced by nitrogen fertilization.This study investigated the impact of nitrogen fertilization on morphophysiological traits in maize(Zea mays L.)and developed algorithms to...The yield of maize(Zea mays L.)is highly influenced by nitrogen fertilization.This study investigated the impact of nitrogen fertilization on morphophysiological traits in maize(Zea mays L.)and developed algorithms to relate manual phenotyping and digital phenotyping of maize with leaf nitrogen and digital field image traits.The experiment included three hybrid maize varieties,V1(Hybrid 981),V2(BARI Hybrid maize-9),and V3(Hybrid P3396),which were evaluated across three nitrogen levels(N1=100 kg N ha^(−1),N2=200 kg N ha^(−1),N3=300 kg N ha^(−1))in a split-plot design with three replications.The results revealed that nitrogen levels(N),varieties(V),and their interactions(V×N)significantly influenced traits such as plant height(PH),leaf area index(LAI),normalized difference vegetation index(NDVI),canopy cover(CC),chlorophyll content(Chl a and Chl b),leaf nitrogen content(LNC),total dry matter(TDM),and grain yield.The hybrid P3396 with 300 kg N ha^(−1)(V3N3)achieved the highest grain yield of 14.45 t ha^(−1),which was statistically similar to that of Hybrid 981 and 300 kg N ha^(−1)(V1N3).Nitrogen significantly improved dry matter accumulation,leaf area,and physiological parameters,with maximum values recorded during flowering.The NDVI,CC,and SPAD were strongly correlated with LNC and TDM,highlighting their potential as indicators for nitrogen management.The digital imaging traits analysed via software effectively differentiated the nitrogen treatments,demonstrating their utility for precise nitrogen application.In conclusion,nitrogen fertilization at 300 kg N ha^(−1) optimized the growth and yield of hybrid maize,with Hybrid P3396 performing best.This study underscores the role of advanced phenotyping tools in improving nitrogen use efficiency and sustainable maize production.展开更多
A four-year field experiment was conducted with two cultivars and four N rate to investigate the spatiotemporal characteristics of leaf senescence in maize after silking and its response to N fertilizer rates on them,...A four-year field experiment was conducted with two cultivars and four N rate to investigate the spatiotemporal characteristics of leaf senescence in maize after silking and its response to N fertilizer rates on them,as well as to reveal the differences in post-silking chlorophyll degradation between low-N-tolerant cultivars.The results showed that the order of leaf senescence after silking in maize was lower leaf>upper leaf>ear leaf,leaf tip>middle>base.Increasing N fertilizer down-regulated the expression of ZmCLH2 and ZmPPH in the leaves at 10-30 d after silking,reducing CLH and PPH activities,thereby delaying the leaf senescence.These effects were more prominent in low-N-sensitive cultivar Xianyu 508(XY508)than in low-N-tolerant cultivar Zhenghong 311(ZH311),especially in the lower leaves and leaf tip.Under low N condition,leaf yellowing and chlorophyll degradation occurred later and slower in ZH311 than in XY508.This resulted in a higher post-silking dry matter accumulation and grain yield in ZH311,which may be one of the important physiological bases of low nitrogen tolerant cultivars.Future research should focus on developing low-N-tolerant maize cultivars with slower leaf senescence near the ear after silking.展开更多
Nitrogen fertilizer is an important agronomic measure significantly affecting crop yield and grain quality.This twoyear study aimed to explore the effects of four nitrogen levels on the morphology,lamellar and crystal...Nitrogen fertilizer is an important agronomic measure significantly affecting crop yield and grain quality.This twoyear study aimed to explore the effects of four nitrogen levels on the morphology,lamellar and crystalline structure,pasting,and rheological properties of proso millet(PM)starch and to investigate potential food applications of PM.The results showed that the starch surface became uneven,and the structure of the starch granules shifted towards greater complexity with increasing nitrogen levels.Nitrogen increased the relative crystallinity,ordered structure,and average repeat distance,leading to a stable starch structure and a higher gelatinization enthalpy.Furthermore,nitrogen significantly increased peak,breakdown,setback,and final viscosities but decreased apparent amylose content,which caused the shear resistance and storage capacity of PM starch-based foods to deteriorate during processing and transport.Rheological analysis showed that PM starch exhibited the typical characteristics of a pseudoplastic fluid.Under nitrogen treatment,PM starch gels showed high potential for application in 3D printing products due to high resistance to shear thinning,gel strength,and yield stress,presumably owing to the significantly higher G′than G′′,and the lower amylose content,which in turn promoted the formation of a stable network structure in water to immobilize more water.Our study provides a reference for applying PM starch in the food industry and for developing PM cropping-management programs to improve quality.展开更多
The present study was conducted to examine photosynthetic characteristics of three dominant grass species （Agropyron cristatum, Leymus chinensis, and Cleistogenes squarrosa） and their responses to burning and nitrog...The present study was conducted to examine photosynthetic characteristics of three dominant grass species （Agropyron cristatum, Leymus chinensis, and Cleistogenes squarrosa） and their responses to burning and nitrogen fertilization in a semiarid grassland in northern China. Photosynthetic rate （Pn）, stomatal conductance （gs）, and water use efficiency （WUE） showed strong temporal variability over the growing season. C. squarrosa showed a significantly higher Pn and WUE than A. cristatum and L. chinensis. Burning stimulated Pn of A. cristatum and L. chinensis by 24-59% （P 〈 0.05） in the early growing season, but not during other time periods. Light-saturated photosynthetic rate （Pmax） in A. cristatum and the maximum apparent quantum yield （Фmax） in A. cristatum and L. chinensis were significantly enhanced by burning （16-67%） in both the fertilized and unfertilized plots. The main effect of burning on Pn, Pmax and Фmax was not significant in C. squarrosa. The burning-induced changes in soil moisture could explain 51% （P= 0.01） of the burning-induced changes in Pn of the three species. All three species showed positive responses to N fertilization in terms of Pn, Pmax, and Фmax. The stimulation of Pn under N fertilization was mainly observed in the early growing season when the soil extractable N content was significantly higher in the fertilized plots. The N fertilization-induced changes in soil extractable N content could explain 66% （P = 0.001） of the changes in Pn under N fertilization. The photosynthetic responses of the three species indicate that burning and N fertilization will potentially change the community structure and ecosystem productivity in the semiarid grasslands of northern China.展开更多
基金Supported by Natural Science Foundation of the Inner Mongolia Autonomous Region(2020MS04001)Inner Mongolia Autonomous Region Science and Technology Program Project+1 种基金Hetao College Science and Technology Research Project(HYYB202303)Hetao College Science and Technology Innovation Team.
文摘A growing global demand exists to formulate plans to lessen the greenhouse gas emissions produced by agricultural activities.The purpose of this study was to uncovered the changes in soil CO_(2)fluxes under varying scenarios including nitrogen fertilization rates,irrigation rates,and air temperatures in the Hetao Irrigation District(HID)over the 38-year period.DAYCENT model was used to predict carbon dioxide(CO_(2))fluxes from cultivated soils in the HID,Inner Mongolia from^(2)023 to 2060(the year of achieving the"carbon neutrality"goal)in this study.Results showed that mean soil CO_(2)fluxes in the sunflower field[1035.13 g/(m^(2).yr)]were significantly lower than those in the maize field[1405.54 g/(m^(2).yr)].An increase in nitrogen fertilization rate led to a significant escalation in soil CO_(2)fluxes.Moreover,elevating irrigation rates for washing salts by irrigation(WSBI)diminished soil CO_(2)fluxes in the sunflower field while amplifying them in the maize field.A rise in air temperature resulted in an increase in soil CO_(2)fluxes from the maize field,with annual increases observed,but a reduction in soil CO_(2)fluxes from the sunflower field.The sunflower fields in the HID have a more substantial advantage than the corn fields in mitigating soil CO_(2)emissions.
基金supported by the Jiangsu Agricultural Science and Technology Innovation Fund(CX(22)2015)the Fundamental Research Funds for the Central Universities(XUEKEN2022008)+1 种基金the Innovation Center for Modern Crop Production Cosponsored by Province and Ministry(CIC-MCP)the Cotton Industry Technology Research System of Shandong Province(SDAIT-03).
文摘Long-term straw return with appropriate nitrogen(N)fertilization increases seedcotton yield and fiber quality,and the root system plays an important role in cotton production.However,under straw return and N fertilization,the relationship between the cotton boll-loading capacity of the root system and seedcotton yield remains unclear.In this study,a ten years of long-term field experiment was conducted in a wheat-cotton rotation system.The effects of straw treatments(straw return and straw removal)and N rates(N0,N75,N150 and N300 representing 0,75,150 and 300 kg N ha^(-1),respectively)on cotton root activity,boll-loading capacity of the root system and their relationship to seedcotton yield from 2019 to 2022 were quantified.The results showed that straw return with an appropriate N fertilization of N150 increased root biomass,the rate and components of root-bleeding sap,as well as boll-loading capacity of the root system and seedcotton yield,but decreased the ratio of root to shoot biomass.Furthermore,the root-bleeding sap rate reached the maximum at 30 d post anthesis(DPA)during the peak boll setting stage.However,the contents of nitrate-N,free amino acids and soluble sugar in root-bleeding sap decreased from 10 DPA.Notably,in 2021 and at 30 DPA,the highest contents of nitrate-N(4.8μg mL^(-1))and free amino acids(8.3μg mL^(-1)),as well as soluble sugar(3.4μg mL^(-1))were observed at N150 under straw return.The increase in seedcotton yield is positively correlated to the soluble sugar content.Straw return significantly increased the boll-loading capacity of the root system,which first increased but then decreased with the increase in N fertilization.Under straw return with N150,the maximum seecotton yield(3455-4544 kg ha^(-1))was recorded,and the largest boll loading(49-54 boll 100 g^(-1))and boll capacity(242-292 g 100 g^(-1))of root system at the boll opening stage were observed.Therefore,straw return with appropriate N fertilization improved root activity and the boll-loading capacity of the root system,thereby increasing seedcotton yield.This study provides new insights into improving seedcotton yield from the perspective of coordinating cotton growth.
基金financially supported by the National Key Research and Development Program of China(2022YFD190160304)Natural Science Foundation of Sichuan Province(2022NSFSC0013)+1 种基金Sichuan Maize Innovation Team Construction Project(SCCXTD-2022-02)National Key Research and Development Program of China(2018YFD0301206)。
文摘Regulating planting density and nitrogen(N)fertilization could delay chlorophyll(Chl)degradation and leaf senescence in maize cultivars.This study measured changes in ear leaf green area(GLA_(ear)),Chl content,the activities of Chl a-degrading enzymes after silking,and the post-silking dry matter accumulation and grain yield under multiple planting densities and N fertilization rates.The dynamic change of GLA_(ear)after silking fitted to the logistic model,and the GLA_(ear) duration and the GLAearat 42 d after silking were affected mainly by the duration of the initial senescence period(T_(1))which was a key factor of the leaf senescence.The average chlorophyllase(CLH)activity was 8.3 times higher than pheophytinase activity and contributed most to the Chl content,indicating that CLH is a key enzyme for degrading Chl a in maize.Increasing density increased the CLH activity and decreased the Chl content,T1,GLAear,and GLA_(ear) duration.Under high density,appropriate N application reduced CLH activity,increased Chl content,prolonged T1,alleviated high-density-induced leaf senescence,and increased post-silking dry matter accumulation and grain yield.
基金Supported by National Key Technology Research and Development Program(2013BAD11B03)National Natural Science Foundation(31272249,31071865,41505100)~~
文摘This experiment was conducted in Xinxiang, Henan from June 2013 to June 2014. Total four treatments were designed including farmers ’ common practice （F, 250 kg/hm^2）, 80% F （LF, 200 kg/hm^2）, 80% F＋biochar （LFC） and no fertilizer （CK） to measure the dynamic emissions of CO2 and N2O from a summer maize-winter wheat field by static chamber-gas chromatography method. The results showed that the soil CO2 emission was 21.8-1 022.7 mg/（m^2·h）, and was mainly influenced by soil temperature and moisture content. During the growth of summer maize, the soil CO2 emission was more significantly affected by soil moisture con-tent; and in winter wheat growing season, it was more significantly affected by soil temperature in the top 5 cm. The LF and LFC treatments significantly reduced the soil cumulative CO2 emission, especial y during the growth of winter wheat. Fertiliza-tion and irrigation were the main factors influencing the soil N2O emission. The soil N2O emission during the fertilization period accounted for 73.9%-74.5% and 40.5%-43.6% of the soil cumulative N2O emission during the summer maize-and winter wheat-growing season, respectively. The peak of emission fluxes was determined by fertilization amount, while the occurrence time of emission peak and emission re-duction effect were influenced by irrigation. The LF treatment reduced the soil cu-mulative N2O emission by 15.7%-16.8% and 18.1%-18.5% during the growth period of summer maize and winter wheat, respectively. Reduced nitrogen fertilization is an effective way for reducing N2O emission in intensive high-yielding farmland. Under a suitable nitrogen level （200 kg/hm^2）, the application of biochar showed no significant effect on the soil N2O emission in a short term. The N2O emission factors of the L and LF treatments were 0.60% and 0.56%, respectively. ln the intensive high-yield-ing farmland of North China, reducing the nitrogen application amount is an appro-priate measure to mitigate greenhouse gas emissions without crop yield loss.
基金Supported by Project of Hubei Agricultural Science and Technology Innovation Center(2014-620-003-003)National Rice Industrial Technology System(CARS-01-63)National Soil Testing and Fertilization Project of China(CNCT09-32)
文摘Under the condition of reduced application of nitrogen fertilizer, the impact of silicor）, zinc and boron on rice growth was investigated by field experiment. The results showed that when the application amount of nitrogen fertilizer was reduced by 20%, the application of silicon, zinc and boron did not reduce the yield of rice, but reduced the incidence of panicle blast in rice and optimized the structure of rice production.
基金financially supported by the National Natural Science Foundation of China (32071943 and 31872853)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (PAPD)
文摘A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs.This study was designed to determine whether optimized nitrogen(N)fertilization could fulfill these multiple goals.In two-year experiments,two high yielding‘super’rice cultivars were grown with different N fertilization management regimes,including zero N input,local farmers’practice(LFP)with heavy N inputs,and optimized N fertilization(ONF).In ONF,by reducing N input,increasing planting density,and optimizing the ratio of urea application at different stages,N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels.Compared with LFP,yield and partial factor productivity of applied N(PFP)under ONF were increased(on average)by 1.70 and 13.06%,respectively.ONF increased starch and amylose content,and significantly decreased protein content.The contents of the short chains of A chain(degree of polymerization(DP)6-12)and B1 chain(DP 13-25)of amylopectin were significantly increased under ONF,which resulted in a decrease in the stability of rice starch crystals.ONF increased viscosity values and improved the thermodynamic properties of starch,which resulted in better eating and cooking quality of the rice.Thus,ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency(NUE)at high yield levels.These results will be useful for applications of high quality rice production at high yield levels.
基金supported by the National Natural Science Foundation of China (30871482)the Scientific Research Innovation Project for Graduate Student of Jiangsu Province, China (CXO7B_184Z)
文摘Grain filling, a crucial stage of grain yield formation in rice, is usually affected by the panicle nitrogen （N） fertilization. Field and pot culture experiments were conducted to explore the underlying mechanisms of N effect. Two rice cultivars with high lodging resistance were grown in the field and pot. Four panicle N fertilization treatments were conducted in 2006 and repeated in 2007. The result showed that medium level of panicle N fertilization treatment （NM） enhanced the accumulation and translocation of non-structural carbohydrate （NSC） in the stem and sheath. Compared with non-nitrogen treatment （NO）, NM promoted the translocation of labeled ^13C from stem and sheath to grain. But, low level of panicle N fertilization treatment （NL） and high level of panicle N fertilization treatment （NH） showed the negative effect. The endosperm cell, grain length, and grain width of NM increased more quickly than that of NO from 4 to 10 d after anthesis. During the early period of grain filling, sucrose-phosphate synthase （EC 2.4.1.14, SPS） activity were significantly higher for the NM treatment than those of the NL and NH treatments. Sucrose synthase （EC 2.4.1.13, SuSase） activity in the grains was substantially enhanced by NM, with the duration of higher activity being longer than those of the other treatments. At maturing stage, NM significantly increased the filled grain number, the seed-setting rate, and the grain weight compared with NL and NH. The results suggest that NM have a positive effect on the activities of enzymes of physiological importance, thereby increasing the grain size and promoting grain filling.
基金supported by the National Natural Science Foundation of China(30030090)National High Tech R&D Program(863 Program)of China(2001AA245041,2001AA115420).
文摘By analyzing and extracting the research progress on nitrogen fertilization in wheat, a dynamic knowledge model for management decision-making on total nitrogen rate, ratios of organic to inorganic and of basal to dressing nitrogen under different environments and cultivars in wheat was developed with principle of nutrient balance and by integrating the quantitative effects of grain yield and quality targets, soil characters, variety traits and water management levels. Case studies on the nitrogen fertilization model with the data sets of different eco-sites, cultivars, soil fertility levels, grain yield and quality targets and water management levels indicate a good performance of the model system in decision-making and wide applicability.
基金supported by the National Natural Science Foundation of China(Nos.41725004,42007007,and 41930753)the Natural Science Foundation of Jiangsu Province,China(No.BK20201104).
文摘Degraded soil aggregation arising from nitrogen(N)fertilization has been reported in many studies;however,the mechanisms have not yet been clarified.Elucidating the impact of N fertilization on soil aggregation would help to improve soil structure and sustain high crop production.The objective of this study was to determine the impact of long-term N fertilization on soil aggregation and its association with binding and dispersing agents.A 12-year(2008–2019)N fertilization field experiment on a Vertisol was performed,covering a wide range of N application rates(0,360,450,540,630,and 720 kg ha-1 year-1)and including straw management(straw return and straw removal)in a wheat(Triticum aestivum L.)-maize(Zea mays L.)cropping system.Soil samples of 0–20 cm depth were collected from 12 field treatments with 3 replications in 2019.Soil aggregate stability(mean weight diameter(MWD))and contents of soil organic carbon(SOC),glomalin-related soil protein(GRSP),microbial biomass carbon(MBC),and mineral N(NH4+and NO3-)were determined.Long-term N fertilization under straw removal conditions reduced soil MWD by 12%–18%at N rates from 0 to 720 kg ha-1 compared to that under straw return(P<0.05).Soil MWD was positively associated with pH(P<0.05)and MBC(P<0.05),but negatively correlated with NH4+(P<0.05)and NO3-(P<0.05).Compared with the straw removal treatment,the straw incorporation treatment significantly improved the contents of aggregating agents(SOC,GRSP,and MBC)(P<0.001),but did not affect that of the dispersing agent(NH4+)(P>0.05);consequently,it improved soil aggregation.Overall,our results indicate that long-term N fertilization may degrade soil aggregation because of the increases in monovalent ions(H+and NH4+)and the decrease in MBC during soil acidification,especially when the applied N dose exceeded 360 kg ha-1 year-1.Our finding can minimize the negative structural impacts on Vertisol.
基金supported,in part,by a scholarship from the China Scholarship Council(CSC)
文摘Minimizing soil ammonia（NH_3） and nitrous oxide（N_2O） emission factors（EFs） has significant implications in regional air quality and greenhouse gas（GHG） emissions besides nitrogen（N） nutrient loss.The aim of this study was to investigate the impacts of different N fertilizer treatments of conventional urea,polymer-coated urea,ammonia sulfate,urease inhibitor（NBPT,N-（n-butyl） thiophosphoric triamide）-treated urea,and nitrification inhibitor（DCD,dicyandiamide）-treated urea on emissions of NH_3 and GHGs from subtropical wheat cultivation.A field study was established in a Cancienne silt loam soil.During growth season,NH_3 emission following N fertilization was characterized using active chamber method whereas GHG emissions of N_2O,carbon dioxide（CO_2）,and methane（CH_4） were by passive chamber method.The results showed that coated urea exhibited the largest reduction（49%） in the EF of NH_3-N followed by NBPT-treated urea（39%） and DCD-treated urea（24%） over conventional urea,whereas DCD-treated urea had the greatest suppression on N_2O-N（87%） followed by coated urea（76%） and NBPT-treated urea（69%）.Split fertilization of ammonium sulfate-urea significantly lowered both NH_3-N and N_2O-N EF values but split urea treatment had no impact over one-time application of urea.Both NBPT and DCD-treated urea treatments lowered CO_2-C flux but had no effect on CH_4-C flux.Overall,application of coated urea or urea with NPBT or DCD could be used as a mitigation strategy for reducing NH_3 and N_2O emissions in subtropical wheat production in Southern USA.
基金Internal Research Project of Shaanxi Provincial Land Engineering Construction Group Co.,Ltd.(DJNY2019-6).
文摘The experiment was conducted in the abandoned land of Liangjia Village,Huayin City,Shaanxi Province from April to September 2019.The experimental crop was spring maize.A total of six treatments were set up in a randomized block design.The moisture content of the top 0-60 cm soil was determined regularly,and the yield and quality indices of maize at maturity were checked.The results show that:(i)combined organic-inorganic fertilization increased the yield of spring maize by 3%-8%.(ii)Compared with CK,fertilization treatments significantly improved the water use efficiency of spring maize,with an increase of 59.2%.The average water use efficiency of three combined organic-inorganic fertilization treatments was 27.81 kg/(ha·mm).Compared with CON,combined application of organic and inorganic fertilizers significantly improved the water use efficiency of spring maize,with an increase of 12.5%.(iii)The combined application of organic and inorganic fertilizers increased the moisture,total starch,crude protein and crude fat contents,and reduced crude fiber content of maize kernels.However,with the increase of the proportion of organic fertilizer,the crude protein content of maize kernels decreased.(iv)Yield of spring maize showed a significant parabolic relationship with soil water consumption.In summary,70%inorganic fertilizer+30%organic fertilizer is a scientific and reasonable way of fertilization.
基金supported by grants from Program for New Century Excellent Talents in University,China(Grant No.NCET-10-0472)the Priority Program Development of Jiangsu Higher Education InstitutionsNational Natural Science Foundation of China(Grant Nos.30971733 and 31171485)
文摘High nitrogen （N） input features China＇s intensive rice production system. To elucidate N and genotype effects on accumulation of macronutrients and micronutrients in grains of japonica rice, and to discuss its significance in rice production, a three-year field experiment involving six japonica rice varieties and seven N treatments were performed. Macronutrients （Ca, Mg, K, and Na） and micronutrients （Cu, Fe, Mn, and Zn） concentrations in brown and milled rice were measured using an atomic absorption spectrophotometer. For macronutrients, no consistently significant effect of N was detected in both brown and milled rice. For micronutrients, N showed significant effect, especially in lowering Zn accumulation in brown and milled rice. In addition, N tended to increase Fe concentration in milled rice. Genotype showed larger effect on distribution of minerals in milled rice than N. The high-yielding variety, Wuyunjing 7, accumulated larger proportion of Mg, K, and Zn in the milled rice as compared with the other five varieties and could be of value for rice breeding programs aiming at high nutritional quality. The results demonstrated differences in response to N between macronutrients and micronutrients, and are of significance for coping with ＇hidden hunger＇ both in humans and crops through agronomical practices.
文摘[Objective] This study aimed to provide certain scientific basis for reasonable application of nitrogen fertilizer in the pollution-free cultivation of Phaseolus vulgaris. [Method] A field experiment was conducted to investigate the effects of different nitrogen fertilization amounts on the prophase yield and economic efficiency of P. vulgaris and available nitrogen content of soil. [Result] With the increased application amount of nitrogen fertilizer, the prophase yield and economic efficiency of P. vulgaris reached the peaks in the Treatment 3 （8 690.48 kg/ hm^2 and 32 222 yuan/hm^2）, and significant differences were found among different treatment groups. With the increased nitrogen fertilization amount, the soil available nitrogen content increased, showing a positive correlation with correlation coefficient of 0.856 5. Excess nitrogen fertilizer reduced the prophase yield and economic efficiency of P. vulgaris. For the open field cultivation of P. vulgaris, the optimum application amount of nitrogen fertilizer was 178 kg/hm^2. [Conclusion] Application of nitrogen fertilizer could effectively increase the soil available nitrogen content.
基金financially supported by the National Basic Research Program of China (2011CB100506)the China Agriculture Research System-Wheat (CARS-03-02A)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-EW-N-08)Research Fund of State Key Laboratory of Soil and Sustainable Agriculture, Nanjing Institute of Soil Science, Chinese Academy of Sciences (Y412201401)
文摘Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consumed by some field practices, such as stubble return and coupled water and nutrient management, soil pH would maintain relatively stable if proper management practices can be adopted in this region.
基金funded by the National Natural Science Foundation of China(30270801).
文摘The effect of nitrogen fertilization on leaf chlorophyll fluorescence was studied in field-grown winter wheat during grain filling underrainfed conditions in Loess Plateau. Results showed that the actual photochemical efficiency of PSⅡ reaction center (F PSⅡ)decreased significantly as leaf water stress progressed, however, the F PS was increased by nitrogen fertilization. The F PSⅡ of 0, 90 and180 kg ha-1 nitrogen treatments at noon were 0.197, 0.279 and 0.283, respectively, which decreased by 57.7, 56.4 and 40.2% as comparedto those in the morning. In the afternoon, the F PSⅡ partialy or completely recovered to the levels in the morning. The values of F PS Ⅱin 0 and 90kgha-1 treatments recovered to 87.3 and 81.5% of those in the morning. In 180kgha-1 treatment, the F PSⅡ in the afternoonwas even higher than that in the morning. Application of nitrogen fertilizer significantly increased maximum photochemical efficiency(Fv/Fm), photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (qNP). These results indicated thatapplication of nitrogen fertilizer could increase the light energy conversion efficiency, the potential activity of photosynthetic reactioncenter, and the non-photochemical dissipation of excess light energy, which can prevent leaf photosynthetic apparatus from damage ofenvironmental stress. However, there was no significant difference in the values of F PSⅡbetween 90 and 180kgha-1 nitrogentreatments, indicating that the excess nitrogen was unfavorable to photosynthesis.
基金supported by the National Natural Science Foundation of China(42330707 and 41930647)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(72221002)the Science and Technology Plan of Sichuan Province,China(2022NSFSC0104).
文摘Widespread soil acidification driven by nitrogen(N)fertilization and precipitation challenges the conventional notion of the long-term stability of soil inorganic carbon(SIC)in agroecosystems.However,the changes in SIC with precipitation and N fertilization remain ambiguous.Based on 4,000+soil samples collected in the 1980s and 2010s and by developing machine learning models to fill the missing SIC of soil samples,this study generated 3,697 paired soil samples between the two periods and then investigated the cropland SIC change and explored its relationship with precipitation and N fertilization across the Sichuan Basin,China.The results showed an overall SIC loss,with a decline of the mean SIC by 15.73%.SIC change varied with initial soil pH and initial SIC and exhibited an exponential relationship with soil pH change,indicating the changing role of carbonates in providing acid-buffering capacity.There was a parabolical relationship between the magnitude of SIC decline and N fertilizer rates,and low N fertilizer rates contributed to a reduction in SIC loss,while SIC loss was promoted by N fertilization occurred when N fertilizing rates exceeded 250 kg ha^(-1) yr^(-1).The change in SIC showed a sinusoidal variation with precipitation,with 950 mm being the threshold controlling whether SIC increased or decreased.Meanwhile,N fertilization did not alter the sinusoidal relationship between SIC change and precipitation.In areas with rainfall<950 mm,the high N fertilizer rate did not cause SIC loss,while higher precipitation could also cause larger SIC loss in areas with lower N fertilizer rates.These results suggest that SIC dynamics are jointly driven by precipitation and N fertilization and are controlled by acid-buffering mechanisms associated with initial pH and SIC,with precipitation being the predominant driver.These findings emphasize the need for more regional soil observations and in-depth studies of SIC change and its mechanisms for accurately estimating SIC change.
基金supported by the Bangladesh Agricultural Research Insti-tute,Gazipur-1701,Bangladesh.This research was also funded by Taif University,Saudi Arabia,Project No.(TU-DSPP-2024-07).
文摘The yield of maize(Zea mays L.)is highly influenced by nitrogen fertilization.This study investigated the impact of nitrogen fertilization on morphophysiological traits in maize(Zea mays L.)and developed algorithms to relate manual phenotyping and digital phenotyping of maize with leaf nitrogen and digital field image traits.The experiment included three hybrid maize varieties,V1(Hybrid 981),V2(BARI Hybrid maize-9),and V3(Hybrid P3396),which were evaluated across three nitrogen levels(N1=100 kg N ha^(−1),N2=200 kg N ha^(−1),N3=300 kg N ha^(−1))in a split-plot design with three replications.The results revealed that nitrogen levels(N),varieties(V),and their interactions(V×N)significantly influenced traits such as plant height(PH),leaf area index(LAI),normalized difference vegetation index(NDVI),canopy cover(CC),chlorophyll content(Chl a and Chl b),leaf nitrogen content(LNC),total dry matter(TDM),and grain yield.The hybrid P3396 with 300 kg N ha^(−1)(V3N3)achieved the highest grain yield of 14.45 t ha^(−1),which was statistically similar to that of Hybrid 981 and 300 kg N ha^(−1)(V1N3).Nitrogen significantly improved dry matter accumulation,leaf area,and physiological parameters,with maximum values recorded during flowering.The NDVI,CC,and SPAD were strongly correlated with LNC and TDM,highlighting their potential as indicators for nitrogen management.The digital imaging traits analysed via software effectively differentiated the nitrogen treatments,demonstrating their utility for precise nitrogen application.In conclusion,nitrogen fertilization at 300 kg N ha^(−1) optimized the growth and yield of hybrid maize,with Hybrid P3396 performing best.This study underscores the role of advanced phenotyping tools in improving nitrogen use efficiency and sustainable maize production.
基金supported by the National Key Research and Development Program of China(2022YFD190160304 and 2018YFD0301206)Natural Science Foundation of Sichuan Province(2022NSFSC0013)Sichuan Provincial Maize Innovation Team Construction Project(SCCXTD-2023-02).
文摘A four-year field experiment was conducted with two cultivars and four N rate to investigate the spatiotemporal characteristics of leaf senescence in maize after silking and its response to N fertilizer rates on them,as well as to reveal the differences in post-silking chlorophyll degradation between low-N-tolerant cultivars.The results showed that the order of leaf senescence after silking in maize was lower leaf>upper leaf>ear leaf,leaf tip>middle>base.Increasing N fertilizer down-regulated the expression of ZmCLH2 and ZmPPH in the leaves at 10-30 d after silking,reducing CLH and PPH activities,thereby delaying the leaf senescence.These effects were more prominent in low-N-sensitive cultivar Xianyu 508(XY508)than in low-N-tolerant cultivar Zhenghong 311(ZH311),especially in the lower leaves and leaf tip.Under low N condition,leaf yellowing and chlorophyll degradation occurred later and slower in ZH311 than in XY508.This resulted in a higher post-silking dry matter accumulation and grain yield in ZH311,which may be one of the important physiological bases of low nitrogen tolerant cultivars.Future research should focus on developing low-N-tolerant maize cultivars with slower leaf senescence near the ear after silking.
基金supported by the Postdoctoral Fellowship Program of China Postdoctoral Science Foudation(CPSF)(GZC20241394)the Shaanxi Province Natural Science Basic Research Program-Youth Project,China(2025JCYBQN271)+2 种基金the National Natural Science Foundation of China(31371529)the Shaanxi Province“Two Chains”Integrated Crop Breeding Key Project,China(2021LLRH07)the Minor Grain Crops Research and Development System of Shaanxi Province,China(NYKJ-2021YL(XN)40)。
文摘Nitrogen fertilizer is an important agronomic measure significantly affecting crop yield and grain quality.This twoyear study aimed to explore the effects of four nitrogen levels on the morphology,lamellar and crystalline structure,pasting,and rheological properties of proso millet(PM)starch and to investigate potential food applications of PM.The results showed that the starch surface became uneven,and the structure of the starch granules shifted towards greater complexity with increasing nitrogen levels.Nitrogen increased the relative crystallinity,ordered structure,and average repeat distance,leading to a stable starch structure and a higher gelatinization enthalpy.Furthermore,nitrogen significantly increased peak,breakdown,setback,and final viscosities but decreased apparent amylose content,which caused the shear resistance and storage capacity of PM starch-based foods to deteriorate during processing and transport.Rheological analysis showed that PM starch exhibited the typical characteristics of a pseudoplastic fluid.Under nitrogen treatment,PM starch gels showed high potential for application in 3D printing products due to high resistance to shear thinning,gel strength,and yield stress,presumably owing to the significantly higher G′than G′′,and the lower amylose content,which in turn promoted the formation of a stable network structure in water to immobilize more water.Our study provides a reference for applying PM starch in the food industry and for developing PM cropping-management programs to improve quality.
基金the National Natural Science Foundation of China (90511006)the Chinese Academy of Sciences (Hundred Talents Program).
文摘The present study was conducted to examine photosynthetic characteristics of three dominant grass species （Agropyron cristatum, Leymus chinensis, and Cleistogenes squarrosa） and their responses to burning and nitrogen fertilization in a semiarid grassland in northern China. Photosynthetic rate （Pn）, stomatal conductance （gs）, and water use efficiency （WUE） showed strong temporal variability over the growing season. C. squarrosa showed a significantly higher Pn and WUE than A. cristatum and L. chinensis. Burning stimulated Pn of A. cristatum and L. chinensis by 24-59% （P 〈 0.05） in the early growing season, but not during other time periods. Light-saturated photosynthetic rate （Pmax） in A. cristatum and the maximum apparent quantum yield （Фmax） in A. cristatum and L. chinensis were significantly enhanced by burning （16-67%） in both the fertilized and unfertilized plots. The main effect of burning on Pn, Pmax and Фmax was not significant in C. squarrosa. The burning-induced changes in soil moisture could explain 51% （P= 0.01） of the burning-induced changes in Pn of the three species. All three species showed positive responses to N fertilization in terms of Pn, Pmax, and Фmax. The stimulation of Pn under N fertilization was mainly observed in the early growing season when the soil extractable N content was significantly higher in the fertilized plots. The N fertilization-induced changes in soil extractable N content could explain 66% （P = 0.001） of the changes in Pn under N fertilization. The photosynthetic responses of the three species indicate that burning and N fertilization will potentially change the community structure and ecosystem productivity in the semiarid grasslands of northern China.
