Grain yield and N uptake of maize in response to increased plant density under reduced water and nitrogen supply conditions

The development of modern agriculture requires the reduction of water and chemical N fertilizer inputs.Increasing the planting density can maintain higher yields,but also consumes more of these restrictive resources.However,whether an increased maize density can compensate for the negative effects of reduced water and N supply on grain yield and N uptake in the arid irrigated areas remains unknown.This study is part of a long-term positioning trial that started in 2016.A split-split plot field experiment of maize was implemented in the arid irrigated area of northwestern China in 2020 to 2021.The treatments included two irrigation levels:local conventional irrigation reduced by 20%(W1,3,240 m^(3)ha^(-1))and local conventional irrigation(W2,4,050 m^(3)ha^(-1));two N application rates:local conventional N reduced by 25%(N1,270 kg ha^(-1))and local conventional N(360 kg ha^(-1));and three planting densities:local conventional density(D1,75,000 plants ha^(-1)),density increased by 30%(D2,97,500 plants ha-1),and density increased by 60%(D3,120,000 plants ha^(-1)).Our results showed that the grain yield and aboveground N accumulation of maize were lower under the reduced water and N inputs,but increasing the maize density by 30% can compensate for the reductions of grain yield and aboveground N accumulation caused by the reduced water and N supply.When water was reduced while the N application rate remained unchanged,increasing the planting density by 30% enhanced grain yield by 13.9% and aboveground N accumulation by 15.3%.Under reduced water and N inputs,increasing the maize density by 30% enhanced N uptake efficiency and N partial factor productivity,and it also compensated for the N harvest index and N metabolic related enzyme activities.Compared with W2N2D1,the N uptake efficiency and N partial factor productivity increased by 28.6 and 17.6%under W1N1D2.W1N2D2 had 8.4% higher N uptake efficiency and 13.9% higher N partial factor productivity than W2N2D1.W1N2D2 improved urease activity and nitrate reductase activity by 5.4% at the R2(blister)stage and 19.6% at the V6(6th leaf)stage,and increased net income and the benefit:cost ratio by 22.1 and 16.7%,respectively.W1N1D2 and W1N2D2 reduced the nitrate nitrogen and ammoniacal nitrogen contents at the R6 stage in the 40-100 cm soil layer,compared with W2N2D1.In summary,increasing the planting density by 30% can compensate for the loss of grain yield and aboveground N accumulation under reduced water and N inputs.Meanwhile,increasing the maize density by 30% improved grain yield and aboveground N accumulation when water was reduced by 20% while the N application rate remained constant in arid irrigation areas.

Manure substitution improves maize yield by promoting soil fertility and mediating the microbial community in lime concretion black soil

Synthetic nitrogen(N)fertilizer has made a great contribution to the improvement of soil fertility and productivity,but excessive application of synthetic N fertilizer may cause agroecosystem risks,such as soil acidification,groundwater contamination and biodiversity reduction.Meanwhile,organic substitution has received increasing attention for its ecologically and environmentally friendly and productivity benefits.However,the linkages between manure substitution,crop yield and the underlying microbial mechanisms remain uncertain.To bridge this gap,a three-year field experiment was conducted with five fertilization regimes:i)Control,non-fertilization;CF,conventional synthetic fertilizer application;CF_(1/2)M_(1/2),1/2 N input via synthetic fertilizer and 1/2 N input via manure;CF_(1/4)M_(3/4),1/4 N input synthetic fertilizer and 3/4 N input via manure;M,manure application.All fertilization treatments were designed to have equal N input.Our results showed that all manure substituted treatments achieved high soil fertility indexes(SFI)and productivities by increasing the soil organic carbon(SOC),total N(TN)and available phosphorus(AP)concentrations,and by altering the bacterial community diversity and composition compared with CF.SOC,AP,and the soil C:N ratio were mainly responsible for microbial community variations.The co-occurrence network revealed that SOC and AP had strong positive associations with Rhodospirillales and Burkholderiales,while TN and C:N ratio had positive and negative associations with Micromonosporaceae,respectively.These specific taxa are implicated in soil macroelement turnover.Random Forest analysis predicted that both biotic(bacterial composition and Micromonosporaceae)and abiotic(AP,SOC,SFI,and TN)factors had significant effects on crop yield.The present work strengthens our understanding of the effects of manure substitution on crop yield and provides theoretical support for optimizing fertilization strategies.

Optimized nitrogen application for maximizing yield and minimizing nitrogen loss in film mulching spring maize production on the Loess Plateau,China

Excessive use of N fertilizers(driven by high-yield goals)and its consequent environmental problems are becoming increasingly acute in agricultural systems.A 2-year field experiment was conducted to investigate the effects of three N application methods(application of solid granular urea once(OF)or twice(TF),application of solid granular urea mixed with controlled-release urea once(MF),and six N rates(0,60,120,180,240,and 300 kg N ha^(-1))on maize yield,economic benefits,N use efficiency,and soil N balance in the maize(Zea mays L.)film mulching system on the Loess Plateau,China.The grain yield and economic return of maize were significantly affected by the N rate and application method.Compared with the OF treatment,the MF treatment not only increased the maize yield(increased by 9.0-16.7%)but also improved the economic return(increased by 10.9-25.8%).The agronomic N use efficiency(NAE),N partial factor productivity(NPFP)and recovery N efficiency(NRE)were significantly improved by 19.3-66.7,9.0-16.7 and 40.2-71.5%,respectively,compared with the OF treatment.The economic optimal N rate(EONR)of the OF,TF,and MF was 145.6,147.2,and 144.9 kg ha^(-1) in 2019,and 206.4,186.4,and 146.0 kg ha^(-1) in 2020,respectively.The apparent soil N loss at EONR of the OF,TF,and MF were 97.1-100.5,78.5-79.3,and 50.5-68.1 kg ha^(-1),respectively.These results support MF as a one-time N application method for delivering high yields and economic benefits,with low N input requirements within film mulching spring maize system on the Loess Plateau.

Effects of Slow-release Nitrogen Fertilizer on Yield and Nitrogen Accumulation of Summer Maize in Shajiang Black Soil Area

[Objectives] This study was conducted to verify the field application effect of slow-release nitrogen fertilizer on summer maize in Shajiang black soil area by simultaneous sowing and fertilization, and explore the application scope and nitrogen metabolism mechanism, so as to lay a foundation for fertilizer reduction and efficiency improvement. [Methods] With maize variety Beiqing 340 and sulfur-coated urea as experimental materials, five nitrogen application levels were set, namely, control (C0), slow-release nitrogen 70 kg/hm^(2) (C70), slow-release nitrogen 140 kg/hm^(2) (C140), slow-release nitrogen 210 kg/hm^(2) (C210) and slow-release nitrogen 280 kg/hm^(2) (C280). The phosphorus and potassium fertilizers were all in accordance with the unified standard. [Results] With the application rate of slow-release nitrogen increasing, the nitrogen accumulation in organs increased first and then decreased after tasseling stage of maize. In order to reduce the fertilizing amount and increase efficiency, 210 kg/hm^(2) of slow-release nitrogen fertilizer was the best fertilizing amount for summer maize in Shajiang black soil area. [Conclusions] This study provides reference for fertilizer reduction, efficiency improvement and sustainable development of summer maize in Shajiang black soil area.

Genetic Diversity and Combining Ability of Developed Maize Lines to Realize Heterotic and High Yielding Hybrids for Arid Conditions

Developing high-yield maize hybrids is critical for sustaining maize production,especially in the face of rapid climate changes and the growing global population.Exploring the genetic diversity and combining ability in parental inbreds is needed for developing such high-yielding hybrids.Consequently,this study aimed at evaluating parental genetic diversity employing simple sequence repeats(SSR)markers,estimating effects of general(GCA)and specific(SCA)combining abilities for grain yield and yield contributing characters,identifying high yielding hybrids,and evaluating the association of SCA effects and performance of hybrids with genetic distance.Half-diallel mating scheme was utilized to develop 21 F_(1) hybrids from seven diverse maize inbred lines.The F_(1) hybrids along with check hybrid(SC-10),were investigated in a field trial over two growing seasons under arid conditions.The assessed F_(1) hybrids displayed significant genetic variations across all recorded traits.The inbreds P_(1) and P_(3) were detected as effective combiners to develop early maturing hybrids.Additionally,P_(3) and P_(4) were recognized as better combiners for improving grain yield and yield attributed characters.The hybrids P_(1)×P_(5) and P_(4)×P_(7) displayed significant SCA effects coupled with favorable agronomic performance.These hybrids are recommended for further evaluation and release as variety for arid environments to increase total maize production and contribute to food security.The alleles per locus differed between 2 and 5,with average of 3.5 alleles/locus.The polymorphic information content(PIC)altered between 0.21 to 0.74,with a mean of 0.56.Unweighted neighbor-joining tree grouped the inbred lines into three clusters,providing a valuable tool to decrease the crosses needed to be assessed in the trial field.Parental genetic distance varied from 0.63 to 0.90,averaging 0.79.The relationship between genetic diversity assessed through SSR markers and SCA effects was insignificant for all considered traits.Otherwise,SCA demonstrated a significant correlation with hybrid performance,suggesting that SCA serves as a reliable predictor for hybrid performance.The assessed maize inbred lines and developed hybrids revealed substantial genetic variability,offering valuable resources for enhancing maize productivity under arid conditions.The identified promising inbred lines(P_(1),P_(3),and P_(4))might be regarded as effective combiners for developing early-maturing genotypes and excellent combiners for enhancing yield attributes.Notably,the developed hybrids P_(1)×P_(5) and P_(4)×P_(7) possessed significant SCA alongside superior yield traits.SCA demonstrated a significant correlation with hybrid performance,suggesting its potential as a reliable predictor for the performance of developed hybrids.

The microbial community,nutrient supply and crop yields differ along a potassium fertilizer gradient under wheat-maize double-cropping systems

Soil microorganisms play critical roles in ecosystem function.However,the relative impact of the potassium(K)fertilizer gradient on the microbial community in wheat-maize double-cropping systems remains unclear.In this long-term field experiment(2008-2019),we researched bacterial and fungal diversity,composition,and community assemblage in the soil along a K fertilizer gradient in the wheat season(K0,no K fertilizer;K1,45 kg ha^(-1) K_(2)O;K_(2),90 kg ha^(-1)K_(2)O;K3,135 kg ha^(-1)K_(2)O)and in the maize season(K0,no K fertilizer;K_(1),150 kg ha^(-1) K_(2)O;K_(2),300 kg ha^(-1)K_(2)O;K_(3),450 kg ha^(-1)K_(2)O)using bacterial 16S rRNA and fungal internally transcribed spacer(ITS)data.We observed that environmental variables,such as mean annual soil temperature(MAT)and precipitation,available K,ammonium,nitrate,and organic matter,impacted the soil bacterial and fungal communities,and their impacts varied with fertilizer treatments and crop species.Furthermore,the relative abundance of bacteria involved in soil nutrient transformation(phylum Actinobacteria and class Alphaproteobacteria)in the wheat season was significantly increased compared to the maize season,and the optimal K fertilizer dosage(K2 treatment)boosted the relative bacterial abundance of soil nutrient transformation(genus Lactobacillus)and soil denitrification(phylum Proteobacteria)bacteria in the wheat season.The abundance of the soil bacterial community promoting root growth and nutrient absorption(genus Herbaspirillum)in the maize season was improved compared to the wheat season,and the K2 treatment enhanced the bacterial abundance of soil nutrient transformation(genus MND1)and soil nitrogen cycling(genus Nitrospira)genera in the maize season.The results indicated that the bacterial and fungal communities in the double-cropping system exhibited variable sensitivities and assembly mechanisms along a K fertilizer gradient,and microhabitats explained the largest amount of the variation in crop yields,and improved wheat?maize yields by 11.2-22.6 and 9.2-23.8%with K addition,respectively.These modes are shaped contemporaneously by the different meteorological factors and soil nutrient changes in the K fertilizer gradients.

Effect of N Fertilization on Yield, N Absorption and Utilization of Two Species of Super High-Yielding Summer Maize

[Objective] The aim was to study on effects of N fertilizer on yield, N absorption and utilization of different cultivars of super high-yielding summer maize, in order to provide reference for reasonable N fertilization in accordance with different cultivars. [Method] Field experiment was conducted to study on effects of different N fertilizers on yield, N absorption and use efficiency of Zhengdan 958 and Xundan 20, in order to learn the effect differences at different N fertilizer levels. [Result] After N was applied, yields of the two summer maize increased significantly. Zhengdan 958 achieved the highest in yield and proceeds at 12 051.18 kg/hm2 and 1 722.40 yuan/hm2, respectively in low N level. In contrast, Xundan 20 achieved the highest at 13 166.00 kg/hm2 and 1 343.92 yuan/hm2 in the above two aspects in high N level. Compared with Zhengdan 958, Xundan 20 increased by 9.90%, 5.20% and 12.00% in N levels of 0, 240, and 450 kg/hm2, respectively. When N fertilizers were applied, protein yield of Xundan 20 was significantly higher than that of Zhengdan 958, so that higher N fertilizers contributed higher protein yield for Xundan 20. In high N level, N efficiency, N-fertilizer utilization and partial productivity of Xundan 20 were significantly higher than that of Zhengdan 958. [Conclusion] Lower N-fertilizer was suitable for Zhengdan 958 and Xundan 20 would get a good harvest if more N-fertilizers were applied. The results provided references for reasonable N fertilization.

Effects of Urea Ammonium Chloride of Different Fertilization Patterns on Maize Yield and Yield Components

[Objective] To understand the application effects of urea ammonium chloride fertilizer on maize production. [Methods] A field plot experiment was conducted to study the effects of urea ammonium chloride of different fertilization patterns on summer maize yield and yield components. [Results] Urea ammonium chloride had a long fertilizer effect and the same yield-increasing effect with urea, which could im- prove the agronomic traits and economic traits of maize apparently and the applica- tion of urea ammonium chloride with nutrient reduction of 40% （namely just use urea ammonium chloride equaled 60% pure nitrogen）, had the same yield-increasing effect with urea of traditional fertilization patterns, and input-output ratio was high and the economic benefit was remarkable. [Conclusion] To provide scientific theoretical direc- tion for large area popularization and application of urea ammonium chloride.

Quantitative design of yield components to simulate yield formation for maize in China

Maize(Zea mays L.) stands prominently as one of the major cereal crops in China as well as in the rest of the world.Therefore,predicting the growth and yield of maize for large areas through yield components under high-yielding environments will help in understanding the process of yield formation and yield potential under different environmental conditions.This accurate early assessment of yield requires accuracy in the formation process of yield components as well.In order to formulate the quantitative design for high yields of maize in China,yield performance parameters of quantitative design for high grain yields were evaluated in this study,by utilizing the yield performance equation with normalization of planting density.Planting density was evaluated by parameters including the maximum leaf area index and the maximum leaf area per plant.Results showed that the variation of the maximum leaf area per plant with varying plant density conformed to the Reciprocal Model,which proved to have excellent prediction with root mean square error(RMSE) value of 5.95%.Yield model estimation depicted that the best optimal maximum leaf area per plant was 0.63 times the potential maximum leaf area per plant of hybrids.Yield performance parameters for different yield levels were quantitatively designed based on the yield performance equation.Through validation of the yield performance model by simulating high yields of spring maize in the Inner Mongolia Autonomous Region and Jilin Province,China,and summer maize in Shandong Province,the yield performance equation showed excellent prediction with the satisfactory mean RMSE value(7.72%) of all the parameters.The present study provides theoretical support for the formulation of quantitative design for sustainable high yield of maize in China,through consideration of planting density normalization in the yield prediction process,providing there is no water and nutrient limitation.

Assessing the Impacts of Climate Change and Variability on Maize (Zea mays) Yield over Tanzania

This study aimed at understanding the impacts of the seasonal hydroclimatic variables on maize yield and developing of statistical crop model for future maize yield prediction over Tanzania. The food security of the country is basically determined by availability of maize. Unfortunately, agriculture over the country is mainly rain fed hence highly endangered by the detrimental consequences of climate change and variability. Observed climate data was acquired from Tanzania Meteorological Authority (TMA) and Maize yield data from Food and Agriculture Organization (FAO). The study used the Mann-Kendall test and Sen’s slope for trend and magnitude detection in minimum, maximum temperature and rainfall at the 95% confidence level. The results have shown that rainfall is decreasing over the country and especially during the growing season but increasing during short rains season. Characteristics of seasonal climatic variables, cycle during growing period were linked to maize yield, and high (low) yield was reported during anomalous wet (dry) growing seasons. This portrays seasonal dependence of maize production. Statistical crop model was built by aggregating spatial regions that have statistically significant relation with maize yield. Results show that, 58.8% of yield variance is linked to seasonal hydroclimate variability. Rainfall emerged as the dominant predictor variable for maize yield since it accounts for 44.1% of yield variance. The modeled and observed yields exhibit statistically substantial relationship (r = 0.78) hence depicting high credence of the built statistical crop model. Also, the results revealed a decreasing trend in Maize yield with further Lessing trend is projected to proceed in the future. This calls for adaptation and implementation of appropriate regional measures to raise maize production in order to feed the burgeoning human population amidst climate change.

Genetic and Agronomic Parameter Estimates of Growth, Yield and Related Traits of Maize (Zea mays L.) under Different Rates of Nitrogen Fertilization

This study evaluated the genetic and agronomic parameter estimates of maize under different nitrogen rates. The trial was established at the Njala Agricultural Research Centre experimental site during 2021 and 2022 in a split block design with three maize varieties (IWCD2, 2009EVDT, and DMR-ESR-Yellow) and seven nitrogen (0, 30, 60, 90, 120, 150 and 180 kg∙N∙ha−1) rates. Findings showed that cob diameter and anthesis silking time (ASI) had intermediate heritability, ASI had high genetic advance, ASI and grain yield had high genotypic coefficient of variation (GCV), while traits with high phenotypic coefficient of variation (PCV) were plant height, ASI, grain yield, number of kernel per cob, number of kernel rows, ear length, and ear height. The PCV values were higher than GCV, indicating the influence of the environment in the studied traits. Nitrogen rates and variety significantly (p < 0.05) influenced grain yield production. Mean grain yields and economic parameter estimates increased with increasing nitrogen rates, with the 30 and 180 kg∙N∙ha−1 plots exhibiting the lowest and highest grain yields of 1238 kg∙ha−1 and 2098 kg∙ha−1, respectively. Variety and nitrogen effects on partial factor productivity (PFPN), agronomic efficiency (AEN), net returns (NR), value cost ratio (VCR) and marginal return (MR) indicated that these parameters were significantly affected (p < 0.05) by these factors. The highest PFPN (41.3 kg grain kg−1∙N) and AEN (29.4 kg grain kg−1∙N) were obtained in the 30 kg∙N∙ha−1 plots, while the highest VCR (2.8) and MR (SLL 1.8 SLL−1 spent on N) were obtained in the 180 kg∙N∙ha−1. The significant influence of variety and nitrogen on traits suggests that increasing yields and maximizing profits require use of appropriate nitrogen fertilization and improved farming practices that could be exploited for increased productivity of maize.

Effects of Zinc on the Yield,Uptake and Distribution of Nitrogen/Phosphorus/Potassium/Zinc in Different Genotypes of Maize

[Objective] To study the effects of Zinc on the yield,nitrogen/phosphorus/potassium/Zinc uptake and distribution of different genotypes of maize.[Method] Using two different genotypes of maize as materials,the effects of Zn on the yield,N/P/K /Zn uptake and distribution of different genotypes of maize were studied by pot cultivation.[Result] Appropriate Zn supply could improve the grain number per kernel.The Zn content in different organs of maize showed little difference under low Zn treatment （Zn0,Zn1）.With the increase of Zn supply,Zn content in leaf,stem and sheath rapidly increased,but the increasing amplitude of Zn content in the kernel and bract were less.The excessive Zn in maize was mainly translocated in lower organs to reduce the damage of them to plants.Different Zn supply levels had less effects on the absorption and translocation of N,P and K in low-Zn insensitive variety Mudan 9.While the absorption and translation of N,P,K in low Zn sensitive variety （Sidan 19） was more easily influenced by the amount of Zn supplied.[Conclusion] Appropriate Zn supply could enhance the maize yield and utilization rate of N and K,and reduce the absorption and utilization of P.

Effects of Planting Density and Nitrogen Amount on Stalk Lodging-Resistance and Yield of Summer Maize in Sichuan Basin

[Objective] The experiment was conducted to explore the suitable planting density and nitrogen amount for summer maize in Sichuan Basin with the objective to provide technical reservation and scientific basis for high-yielding cultivation technique.[Method] A widely planted maize cultivar ＇Chengdan 30＇ was used as experimental material to study the effects of planting density and nitrogen amount on the stalk agronomic traits,stalk lodging-resistance mechanical characters,stalk breaking percentage and yield of maize.Experiment was arranged in a two-factor split plot design with three replicates.The planting density was the main factor with three density gradients（4.5×10^4,6.0×10^4 and 7.5×10^4 plants/hm^2） and the nitrogen amount was the second factor with two different levels of nitrogen content（300 and 375 kg/hm^2）.[Result] The stalk lodging-resistance and yield were affected by planting density significantly.The increase of planting density would result in an increase of internode length and decrease of internode diameter,dry matter weight of per unit stalk length,rind penetration strength and breaking resistance of 3rd and 4th basal internodes.When planting density increased from 6.0×10^4 plants/hm2 to 7.5×10^4 plants/hm^2,the stalk breaking percentage in the whole growing season increased by 17.17%,and the yield reduced by 17.58%.The interaction between planting density and nitrogen amount affected the stalk breaking percentage in the whole growing season and yield significantly.The treatment with planting density of 6.0×104 plants/hm^2 and nitrogen amount of 375 kg/hm^2 of pure N was an optimal combination,which may not only control the stalk breaking percentage of whole growing stage effectively,but also could obtain an optimum grain yield.[Conclusion] In Sichuan Basin,the appropriate planting density and nitrogen amount for summer maize were 6.0×10^4 plants/hm^2 and 375 kg/hm^2.

Effects of a New Long-term Controlled-release Fertilizer on Growth and Development and Yield of Summer Maize

[Objective] The aim was to select the optimal amount of controlled-release fertilizer and provide theoretical references for controlled-release fertilizers use in summer maize. [Method] Long-term controlled-release fertilizers were applied once at sowing summer maize to explore effects on maize growth, yield, economic profits and environment. [Result] Maize yield reduced a little in the treatment group with 60% CRF, and increased in varying degrees in the rest groups in the range of 1.1%-7.4%, and some showed significant differences. [Conclusion] Controlled-release fertilizers can be applied once at the amount of 80% common fertilizer＇s, with con- sideration of maize yield, nitrogen use rate and economic profits, which is beneficial for summer maize application and promotion in North China.

Effects of Climate Changes on Maize Yield in Northeast China

Based on the meteorological data and production data of maize of 10 stations in Northeast China from 1961 to 2006,the primary climatic factors influencing maize yield in different region were studies by the method of Baier yields models.The result showed that the yield of maize in Heilongjiang and Jilin Province were mainly affected by temperatures,with air temperature increased,the meteorological yield of maize increased.The meteorological yield of maize in Liaoning Province was mainly affected by precipitation and sunshine duration,and different regions had different effects.

Effects of Postponing N Application on Metabolism,Absorption and Utilization of Nitrogen of Summer Maize in SuperHigh Yield Region

[Objective] The aim was to explore effects of application postponing of N fertilizer and the mechanism of yield increase in order to provide references for N fertilizer application in a rational way. [Method] In a super-high yielded region of summer maize, field experiment was conducted to research effects of N fertilizer postponing on key enzymes of N metabolism, yield of maize and N fertilizer use. [Result] After application of N fertilizer was postponed, NR, SPS and GS activities of ear-leaf of summer maize increased by 11.99%-34.87%, 8.25%-10.64% and 10.00%- 16.81% on the 28^th d of silking; content of soluble sugar in leaves enhanced signifi- cantly and accumulated nitrogen increased by 5.00%-9.74% in mature stage. The postponing fertilization of ＂30% of fertilizer in seedling stage＋30% of fertilizer in flare- opening stage＋40% of fertilizer in silking stage meets N demands of summer maize in late growth period. Compared with conventional fertilization, the maize yield, agro- nomic efficiency and use of N fertilizer all improved by 5.05%, 1.75 kg/kg and 6.87%, respectively, after application postponed. [Conclusion] Application postponing of N fertilizer maintains activity of NR, GS and SPS higher and coordinates metabolism of C and N in late growth period, to further improve yield of maize.

Effects of Slow-release Nitrogen on Dry Matter Accumulation,Translocation and Yield of Summer Maize

[Objectives]This study was conducted to investigate the effects of slow-release nitrogen fertilizer on dry matter accumulation and translocation of summer maize.[Methods]With Zhoudan 9 as the test variety,six different treatment were set up:blank control(CK1),slow-release urea 75 kg/hm^(2)(C1),slow-release urea 150 kg/hm^(2)(C2),slow-release urea 225 kg/hm^(2)(C3),slow-release urea 300 kg/hm^(2)(C4)and ordinary urea 300 kg/hm^(2)(CK2),to study the change law of dry matter accumulation and translocation in summer maize.[Results]Treatment slow-release urea 225 kg/hm^(2)(C4)showed summer maize yield,dry matter translocation between organs,grain contribution rate and proportion of grain dry matter in the full ripe stage higher than other treatments.Considering the weight loss and cost factors,slow-release urea 225 kg/hm^(2)(C3)could be recommended as the fertilizing amount for summer maize.[Conclusions]This study provides theoretical reference for rational selection of fertilizers for reducing fertilizer application and increasing fertilizer efficiency,and for production of summer maize in Shajiang black soil region.

Assessing the Influence of Phosphorus Fertilization on the Growth and Yield of Maize/Soybean Intercrop by Analyzing Nitrogen Uptake

Intercropping, particularly the combination of maize and soybeans, has been widely recognized for its potential to improve nitrogen uptake and promote sustainable agriculture. This study examines the patterns of nitrogen uptake in maize and soybean intercropping systems under different growth stages and phosphorus fertilization levels and investigates the influence of nitrogen uptake on growth parameters such as plant height, leaf area, and biomass accumulation in the maize/soybean intercrop under different phosphorus fertilization regimes. The study also collected chlorophyll samples at different growth stages of maize in monoculture and intercropping with maize or soybean. The results showed that plant height was greater in V10 in both fertilized and unfertilized treatments for intercropped maize and soybean, and chlorophyll concentration was higher in VT intercropped maize. The results also showed a higher accumulation of biomass. Understanding the growth dynamics of these plants in monoculture and intercropping systems and the impact of fertilization practices is crucial for optimizing crop productivity and sustainability in agricultural systems.

Effects of Controlled-Release Nitrogen on Yield and Nitrogen Use Efficiency of Summer Maize

The field experiments were conducted in Anhui during 2016 to investigate the effects of controlled-release nitrogen （CRN） rates and mixture of controlled-re- lease nitrogen and conventional nitrogen （CN） on the yield and nitrogen efficiency of summer maize. Six treatments included CK （with no application of N）, CNIO0% splits （CN）, CRFIO0% （CRN1）, CRN60%＋CN40% （CRN2）, CRN85% （CRN3） and CRN70% （CRN4）. The results showed proper CRN increased yields and output val- ue. Compared with CN, CRN2 significantly increased by 13.74%, CRN1 increased by 4.84%, and CRN3 was equal to CN. CRN increased yield by grain number per spike of yield components. CRN2 had the highest apparent nitrogen fertilizer recov- ery efficiency and CRN1 was the second, which were significantly higher than CN. Nitrogen agronomic efficiency of CRN2 was significantly higher than CN. Nitrogen physiological efficiency of CRN2 was higher than CN. The partial productivity of CRN1 was higher than that with CN. And the effect of nitrogen fertilizer of CRN2 was the highest, which was increased 758 yuan/hm2. Considering yield, nitrogen use efficiency and economic benefit, applying the mixture of CRN and CN was the most beneficial treatment. CRN1 was the second treatment, and CRN3 didn＇t reduce yield.

Response of phenology- and yield-related traits of maize to elevated temperature in a temperate region

Extreme high temperatures detrimental to maize production are projected to occur more frequently with future climate change.Phenology and yield-related traits were investigated under several levels of elevated temperature in two early-maturing hybrid cultivars:Junda 6(grown in northeastern China)and Chalok 1(grown in South Korea).They were cultivated in plastic houses in Suwon,Korea(37.27°N,126.99°E)held at target temperatures of ambient(AT),AT+1.5°C,AT+3°C,and AT+5°C at one sowing date in 2013 and three different sowing dates in 2014.Vegetative and reproductive growth durations showed variation depending on sowing date,experimental year,and cultivar.Growth duration tended to decrease,but not necessarily,with temperature elevation,but somewhat increased again above a certain temperature.High temperature-dependent variation was greater during grain filling than in the vegetative period before anthesis.Elevated temperature showed no significant effects on duration or peak dates of silking and anthesis,and thus on anthesis–silking interval.Grain yield tended to decrease with temperature elevation above ambient,showing a sharper linear decrease with mean growing season temperature increase in Junda 6 than in Chalok 1.The decrease in kernel number accounted for a much greater contribution to the yield reductions due to temperature elevation than did the decrease in individual kernel weight in both cultivars.Individual harvestable kernel weight was not significantly affected by temperature elevation treatments.Kernel number showed a linear decrease with mean growth temperature from early ear formation to early grain-filling stage,with Junda 6 showing a much severer decrease than Chalok 1.Kernel number reduction due to temperature elevation was attributable more to the decrease in differentiated ovule number than to the decrease in kernel set in Chalok 1,but largely to the decrease of kernel set in Junda 6.