Effects of Different Nitrogen Application Rates and Methods on Root Nodule Growth and Yield of Soybean

This study was conducted wiffl a spring soybean variety Jindou 19 to test file effects of rhizobia inoculation or non-inoculation and nitrogen application rates at 0, 27, 54 and 75 kg/hm^2 （N1-4） on root nodule dry weight, root nodule number, yield and yield components of soybean. The results showed that the nitrogen fertilizer significantly affected soybean root noduce and soybean yield, the dry weight and number of root nodules increased gradually with the increase of nitrogen application rate, and the yield of file rhizobia inoculated treatment was significantly higher than that of file rhizobia non-inoculated treatment; and under file condition of file rhizobia inoculation, with nitrogen application amount at 75 kg/hm^2, file Jindou 19 performed a better nitrogen fixing effect in file growing stage, and its plot yield was 4 997.417 kg/hm^2, 4.06% higher than that of file treatment without inoculating rhizobium and 12.50% higher than that of the treatment without applying nitrogen fertilizer.

Determination of optimum nitrogen application rates in Zhejiang Province, China, based on rice yields and ecological security

Excessive nitrogen（N） fertilization in intensive agricultural areas such as the plain region of South China has resulted in low nitrogen use efficiency and serious environmental problems. To determine the optimum N application rate, grain yield, apparent nitrogen recovery efficiency（ANRE）, apparent N loss, and ammonium（NH_3） volatilization under different N application rates in the three years from 2012 to 2014 were studied. The results showed that the relationship between grain yields and N application rate in the three years were well fitted by quadratic equations. When N application rate reached 197 kg ha^（–1） in 2012, 199 kg ha^（–1） in 2013 and 196 kg ha^（–1） in 2014, the plateau of the grain yields appeared. With the increase of N application rate, the ANRE for rice decreased which could be expressed with sigmoidal equation; when N application rate was 305 kg ha^（–1） in 2012, 275 kg ha^（–1） in 2013 and 312 kg ha^（–1） in 2014, the curves of ANRE appeared turing points. Besides, the relationship between soil Nresidual and N application rate was fitted by the quadratic equation and the maximums of soil Nresidual were reached in the three years with the N application rate of 206, 244 and 170 kg ha^（–1）, respectively. Statistical analysis indicated that NH3 volatilization and apparent N loss in three years all increased with the increasing N application rate. When the amount of NH3 volatilization increased to 11.6 kg N ha^（–1） in 2012, 40.5 kg N ha^（–1） in 2013 and 57.0 kg N ha^（–1）in 2014, the apparent N loss in the three years had obvious increase. To determine the optimum N application rate, the average N application on the plateau of the grain yield was considered as the lower limit while the average N application rate at the turning points of ANRE, the residual N in soil and apparent N loss was taken as the upper limit. According to the results in three years, the optimum N application rate for rice in Zhejiang was 197–255 kg ha^（–1）.

Differing responses of root morphology and physiology to nitrogen application rates and their relationships with grain yield in rice

Root morphology and physiology influence aboveground growth and yield formation in rice.However,root morphological and physiological differences among rice varieties with differing nitrogen(N)sensitivities and their relationship with grain yield are still unclear.In this study,rice varieties differing in N sensitivity over many years of experiments were used.A field experiment with multiple N rates(0,90,180,270,and 360 kg ha^(-1))was conducted to elucidate the effects of N application on root morphology,root physiology,and grain yield.A pot experiment with root excision and exogenous application of 6-benzyladenine(6-BA)at heading stage was used to further verify the above effects.The findings revealed that(1)under the same N application rate,N-insensitive varieties(NIV)had relatively large root biomass(root dry weight,length,and number).Grain yield was associated with root biomass in NIV.The oxidation activity and zeatin(Z)+zeatin riboside(ZR)contents in roots obviously and positively correlated with grain yield in N-sensitive varieties(NSV),and accounted for its higher grain yield than that of NIV at lower N application rates(90 and 180 kg ha^(-1)).(2)The root dry weight required for equal grain yield of NIV was greater than that of NSV.Excision of 1/10 and 1/8 of roots at heading stage had no discernible effect on the yield of Liangyoupeijiu(NIV),and it significantly reduced yield by 11.5%and 21.3%in Tianyouhuazhan(NSV),respectively,compared to the treatment without root excision.The decrease of filled kernels and grain weight after root excision was the primary cause for the yield reduction.Root excision and exogenous 6-BA application after root excision had little influence on the root activity of NIV.The oxidation activity and Z+ZR contents in roots of NSV decreased under root excision,and the increase in the proportion of excised roots aggravated these effects.The application of exogenous 6-BA increased the root activity of NSV and increased filled kernels and grain weight,thereby reducing yield loss after root excision.Thus,the root biomass of NIV was large,and there may be a phenomenon of"root growth redundancy."Vigorous root activity was an essential feature of NSV.Selecting rice varieties with high root activity or increasing root activity by cultivation measures could lead to higher grain yield under lower N application rates.

Magnesium fertilizer application increases peanut growth and pod yield under reduced nitrogen application in southern China

This study investigated the effect of magnesium application on peanut growth and yield under two nitrogen(N)application rates in acidic soil in southern China.The chlorophyll content,net photosynthetic rate and dry matter accumulation of the N-sensitive cultivar decreased under reduced N treatments,whereas no effect was observed on the relevant indicators in the N-insensitive variety GH1026.Mg application increased the net photosynthetic rate by increasing the expression of genes involved in chlorophyll synthesis and Rubisco activity in the leaves during the pegging stage under 50%N treatment,while no effect on the net photosynthetic rate was observed under the 100%N treatment.The rate of dry matter accumulation at the early growth stage,total dry matter accumulation and pod yield at harvest increased after Mg application under 50%N treatment by increasing the transportation of assimilates from stems and leaves to pods in both peanut varieties,whereas no effect was found under 100%N treatment.Moreover,Mg application increased the NUE under 50%N treatment.No improvement of NUE in either peanut variety was found under 100%N treatment,while Mg application under the 50%N treatment can obtain a higher economic benefit than the 100%N treatment.In acidic soil,application of 307.5 kg ha^(-1)of Mg sulfate fertilizer under 50%reduced nitrogen application is a suitable fertilizer management measure for improving carbon assimilation,NUE and achieve high peanut yields in southern China.

Effects of Nitrogen Application Rate on Yield and Quality of Different Genotypes of Foxtail Millet

In order to elucidate the response mechanism of yield and quality of different genotypes of foxtail millet to nitrogen application.In this study,plant physiology and metabolomics were used to study the effects of different amounts of nitrogen(0,75,150,225 and 300 kg hm^(-2))on agronomic characters,yield and quality of Jingu 21 and Zhangza 10.The results showed that with the increase of nitrogen application,the plant height of different genotypes of foxtail millet increased gradually,and the content of stem diameter,yield,protein,fat,lysine,phenylalanine,isoleucine,arginine,aspartic,glutamic,glycine,and proline content of different genotypes of foxtail millet showed an increasing and then decreasing trend.The highest yield was recorded in Jingu 21 at 150 kg hm^(-2),and the highest yield was recorded in Zhangza 10 at 225 kg hm^(-2) of nitrogen application.Yield of Jingu 21 was positively correlated with protein and tryptophan content(r=0.91).The yield of Zhangza 10 was positively correlated with fibre content(r=0.89).The protein content of different genotypes of foxtail millet were negatively correlated with the peak viscosity(PV),trough viscosity(TV)and breakdown value(BD).The results of this study clarify that the optimal nitrogen application of Jinguu 21 was 150 kg hm^(-2),and that of Zhangza 10 was 225 kg hm^(-2).The regulation effect of nitrogen on foxtail millet was clarified,which laid the theoretical and technical foundation for foxtail millet cultivation with high yield and high quality.

Effects of Plant Density and Nitrogen Application Rate on Grain Yield and Nitrogen Uptake of Super Hybrid Rice

The nitrogen uptake, yield and its components for two super-high-yielding hybrid rice combinations, Guodao 6 and Eryou 7954 were investigated under different plant densities （15, 18, and 21 plants/m^2） and different nitrogen application rates （120, 150, 180, and 210 kg/hm^2）. The experiment was conducted on loam soil during 2004-2006 at the experimental farm of the China National Rice Research Institute in Hangzhou, China. In these years, the two hybrid rice cleady showed higher yield at a plant density of 15 plants/m^2 with a nitrogen application rate of 180 kg/hm^2. Guodao 6 produced an average grain yield of 10 215.6 kg/hm^2 across the three years, while the yield of Eryou 7954 was 9 633.0 kg/hm^2. With fewer plants per unit-area and larger plants in the plots, the two hybrid rice produced more panicles per plant in three years. The highest nitrogen uptake of the two hybrid rice was at a plant density of 15 plants/m^2 with a nitrogen application rate of 180 kg/hm^2. Further increasing nitrogen application rate was not advantageous for nitrogen uptake in super-high-yielding rice under the same plant density.

Effects of Increased Planting Density with ReducedNitrogen Application on Yield Formation and NitrogenUtilization of Autumn Maize

With the change of cropping system in the middle reaches of the Yangtze River,the planting area of autumn maize is gradually increasing.However,the cultivation techniques are still under improvement for higher yield and nitrogen efficiency of autumn maize.Increase in planting density with reduced nitrogen fertilizer application is one of the important paths to achieve high yield and high nitrogen utilization efficiency.Meanwhile,the effect needs to be verified for autumn maize.The semi-compact autumn maize variety Qinyu 58 was planted under different planting densities and nitrogen fertilizer amounts with the split plot design.Different nitrogen application rates were arranged in the main plots,including the conventional nitrogen application(N300,300 kg/hm^2),30%reduction from the conventional treatment(N210,210 kg/hm^2)and no nitrogen application(N0).Different planting densities were arranged in the sub-split plots,including the conventional planting density(D60,60000 plants/hm2),medium density(D78,78000 plants/hm^2)and high density(D93,93000 plants/hm2).The effects of nitrogen fertilizer,planting density and their interaction effects on canopy structure,dry matter accumulation,yield and nitrogen use efficiency of autumn maize were studied.The nitrogen application rate and planting density had obvious interaction effects on the yield formation of autumn maize.Compared with the conventional cultivation(N300D60),increasing the planting density with 30%reduction in nitrogen application(N210)can obviously increase the canopy light interception rate,LAI,dry matter accumulation and yield.However,there was no significant change in canopy light interception rate,LAI,dry matter accumulation,grain weight and yield between D93 and D78.Compared with N300D60,nitrogen translocation efficiency and nitrogen contribution proportion to grain nitrogen did not change significantly in autumn maize grown under N210 and D78 treatments,whereas nitrogen partial productivity,nitrogen agronomic efficiency and recovery and utilization efficiency of nitrogen fertilizer increased significantly.Moreover,high density(D93)planting at N210 plots significantly improved nitrogen transport efficiency and utilization efficiency in autumn maize.Therefore,the suitable planting density of the autumn maize variety Qinyu 58 in Hubei Province is recommended a value of 78000 plants/hm^2,with the nitrogen application rate of 210 kg/hm2,which can achieve the target of higher yield by increasing density and reducing nitrogen.

Effects of Density and Nitrogen Application Rate on Population Structure and Yield of Early-maturing Late Japonica Tongjing 981

The study adopted split block design with different treatment levels of density and fertilizer to investigate the growth period,population tiller dynamics,leaf area,dry matter accumulation,plant traits,panicle-grain structure,yielding ability and stress resistance of Tongjing 981 under different density and nitrogen fertilizer levels,so as to make clear the effects of different densities and nitrogen fertilizer levels on the population development and yield of Tongjing 981.The results showed that a too-low density was not conductive to the formation of sufficient number of panicles,and when the density was too high,it affected the number of grains per panicle and 1000-grain weight;and when nitrogen fertilizer was at a too-low level,it would restrict the population development,and a too-high nitrogen fertilizer easily led to the extension of the growth period and the aggravation of sheath blight.Reasonable density and fertilization level could make the development of individuals in Tongjing 981 population coordinated,and further help to establish a reasonable population structure,maintain a high leaf area and dry matter accumulation during the filling period,and balance the relationship of population dry matter weight with economic coefficient and panicle,grain and weight,thereby improving the population quality and yield of Tongjing 981.

Effect of Different Nitrogen Application Rate on Rice Stem Characteristics

The effects of different nitrogen application rate on the physical characteristics and anatomic structure of rice stems were investigated with rice cultivars Guangliangyou 1128 （with high resistance） and Zhunliangyou 527 （with low resistance） as materials. The results showed that, firstly, plant height, gravity center height and basal internode length of the 2 rice cultivars increased with the increase of nitrogen application rate, while wall thickness and internode filling degree decreased. The breaking-resistance strength per stem and thrust-resistance strength of plants declined with the increase of nitrogen application rate. Secondly, as nitrogen input increased, the number of vascular bundles and the area of vascular bundles increased between the 2 rice cultivars. Thirdly, with the increase of nitrogen application rate, the stem section area of Guangliangyou 1128, which had strong lodging resistance, gradually increased, while that of Zhunliangyou 527 increased firstly and then decreased. The maximum application amount of nitrogen was 240 kg/hm 2. Nitrogen fertilizer mainly affected the relative gravity center height, stem wall thickness and internode filling degree of the 2 cultivars, thereby reducing the basal stem breaking resistance and plant thrust-resistance strength.

Effects of Supplemental Irrigation Based on Testing Soil Moisture and Nitrogen Fertilization Amount on the Yield and Nitrogen Uptake of Winter Wheat

[Objective] This study aimed to determine the effects of supplemental irrigation on yield and nitrogen uptake in winter wheat. [Method] Three supplemental irrigation levels were set based on the target soil contents of 60%, 70% and 80%） at jointing stage of wheat. Moreover, three nitrogen levels （0, 195 and 255 kg/hm^2） were designed. The experimental plots were arranged fol owing a split-plot design. Zhoumai 18 was selected as the experimental material. [Result] Supplemental irrigation and nitrogen application in combination had significant or extremely significant effects on yield, yield components and nitrogen uptake in winter wheat. The interaction between irrigation and nitrogen fertilization had significant or extremely significant influence on the number of ears, number of grains per ear, 1 000-grain weight, grain yield and nitrogen accumulation in winter wheat. Under different combinations of supplemental irrigation and nitrogen application, the maximum yield of winter wheat was obtained at W2 N195, while the minimum at W1 N255. [Conclusion] With the increase of irrigation, negative effect of nitrogen on number of ears, number of grains per ear, 1 000-grain weight, grain yield and nitrogen accumulation decrease under lower nitrogen application rate.

Response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 in Northeast China

The objective of this study was to identify the response of grain yield to plant density and nitrogen rate in spring maize hybrids released from 1970 to 2010 and grown extensively in Northeast China.Twenty-one hybrids were grown for 2 years in Northeast China at densities of 30,000,52,500,75,000,and 97,500 plants ha^(-1)and N application levels of 0,150,300,and 450 kg N ha^(-1).Irrespective of density or nitrogen application rate,grain yields both per plant and per unit area were significantly higher for newer than older hybrids.As plant density increased from 30,000 to 97,500 plant ha^(-1),yield per plant of 1970 s,1980 s,1990 s,and 2000 s hybrids decreased by 50%,45%,46%,and 52%,respectively.The response of grain yield per unit area to plant density was curvilinear.The estimated optimum plant densities were about 58,000,49,000,65,000,and 65,000 plants ha^(-1)for hybrids released in the 1970 s,1980s,1990 s,and 2000 s,respectively.The theoretical optimum densities for the hybrids released from the 1970 s to the 2000 s increased by 1750 plants ha^(-1)decade^(-1).Nitrogen fertilization significantly increased grain yields per plant and per unit area for all hybrids.The theoretical optimum N application rates for high yield for hybrids released in the 1970 s and 1980 s were about 280 and 360 kg ha^(-1),and the hybrids from the 1990 s and 2000 s showed highest yield at 330 kg ha^(-1)N.No significant difference in the grain yields of 2000 s hybrids between the N levels of 150 to 450 kg ha^(-1)was found.Significant yield gains per plant and per unit area were found,with average increases of 17.9 g plant^(-1)decade^(-1)and936 kg ha^(-1)decade^(-1)over the period 1970–2010,respectively.Yield gains were attributed mainly to increased yield per plant,contributed by increases in kernel number per ear and1000-kernel weight.The rates of lodging and barren plants of newer hybrids were significantly lower than those of older ones,especially at high plant density.

Perspective on oil flax yield and dry biomass with reduced nitrogen supply

Field experiment was arranged in a randomized complete block design to determine effects of nitrogen(N)application levels(J0:150 kg/hm^2,J1:120 kg/hm^2,J2:90 kg/hm^2,J3:60 kg/hm^2)on regulating dry biomass accumulation,allocation and translocation,and grain yield of oil flax during 2018 cropping season.Significant promotion was observed in dry matter during accumulation stage of oil flax,when N rate was reduced by 40%(from 150 to 90 kg/hm^2).Under J2 treatment,translocation of dry matter from vegetative organs to pod increased by 38.46%and 61.54%respectively,when compared with J1 and J0 treatment Dry matter distribution proportion of pod at maturity increased 4.47%-7.61%,contribution rate of leaf to grain upgraded 5.09%-8.77%,and number of effective pods and grains per pod increased by 27.16%-45.38%and 6.49%-26.59%respectively compared to other treatments.As a result,seed yield of oil flax under J2 treatment was 2.23%-18.21%higher than those of other treatments.Our study recommended 90 kg/hm^2 as the best N fertilizer level to improve seed yield of oil flax.

Effects of Different Nitrogen Levels on Growth and Nitrogen Utilization of Sugarcane

[Objectives]To systematically study the effects of different nitrogen levels on the growth and nitrogen utilization of sugarcane in Guangxi.[Methods]Through field experiment and indoor analysis,different nitrogen application levels were set up to determine soil nitrogen content and sugarcane nitrogen content.The effects of different nitrogen levels on sugarcane yield,agronomic characters and nitrogen utilization were studied.[Results]The effect of nitrogen application rate on sugarcane yield showed a quadratic curve,and nitrogen application could significantly increase sugarcane yield,and the sugarcane yield reached the maximum when the nitrogen application rate reached 714 kg/ha.[Conclusions]With the increase of nitrogen application rate,sugarcane yield increased,but when it exceeded a certain range,the sugarcane yield decreased significantly.

Study on High-yield Potential for Maize Varieties in Mountain Area of Yunnan-Guizhou Plateau

By field experiments with Uniform Design, the effects of planting density and nitrogen rate on three varieties （Yunrui No.8, Yunrui No.6 and Yunrui No.88） grain yield under different ecological conditions were studied in Yunnan Province. The results showed that the grain yields were different among the five experiment locations, when increasing of planting density, it did not affected the plant height, ear height and ear factor, with the planting density increased, stem diameter, leaf width, ear length, number of grains per row and 1 000-grain weight decreased sig- nificantly, but the grain yield of the third varieties increased. High planting density had a negative impact on ear traits, but the grain yield increased by high-density compensate for the adverse effects.Control space and time of fertilizer application can reach the highest yield under less Nitrogen fertilizer Yunrui 88 had the charec- teristics of wide range of adaptability and the density-tolerance, high-yielding poten- tial, which was favorable in planting on large areas.