Nitrogen(N) and seeding rates are important factors affecting grain yield and N use efficiency(NUE) in directseeded rice. However, these factors have not been adequately investigated on direct-seeded and double-season...Nitrogen(N) and seeding rates are important factors affecting grain yield and N use efficiency(NUE) in directseeded rice. However, these factors have not been adequately investigated on direct-seeded and double-season rice(DDR) in Central China. The objective of this study was to evaluate the effects of various N and seeding rates on the grain yield and NUE of an ultrashort-duration variety grown under DDR. Field experiments were conducted in 2018 in Wuxue County and 2019 in Qichun County, Hubei Province, China with four N rates and three seeding rates.The results showed that the grain yield of the ultrashort-duration variety ranged from 6.32 to 8.23 t ha–1with a total growth duration of 85 to 97 days across all treatments with N application. Grain yield was increased significantly by N application in most cases, but seeding rate had an inconsistent effect on grain yield. Furthermore, the response of grain yield to the N rates was much higher than the response to seeding rates. The moderate N rates of 100–150 and 70–120 kg N ha–1in the early and late seasons, respectively, could fully express the yield potential of the ultrashort-duration variety grown under DDR. Remarkably higher N responses and agronomic NUE levels were achieved in the early-season rice compared with the late-season rice due to the difference in indigenous soil N supply capacity(INS) between the two seasons. Seasonal differences in INS and N response should be considered when crop management practices are optimized for achieving high grain yield and NUE in ultrashort-duration variety grown under DDR.展开更多
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 r...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.展开更多
A building integrated photovoltaic (PV) and fuel cell (FC) system is proposed for assessment of the energy self-sufficiency rate in a city in Japan. The electricity consumed in the building is mainly supplied by solar...A building integrated photovoltaic (PV) and fuel cell (FC) system is proposed for assessment of the energy self-sufficiency rate in a city in Japan. The electricity consumed in the building is mainly supplied by solar panels, while the gap between the energy demand and supply is solved by the FC that is powered by the H2 produced by water electrolysis with surplus power of PV. A desktop case study of using the proposed system in Tsu city which is located in central part of Japan, has been conducted. The results found that the self-sufficiency rates of PV system to electricity demand of households (RPV) during the daytime in April and July are higher than those in January and October. The results also reveal that the self-sufficiency rate of FC system to the electricity demand (RFC) is 15% - 38% for the day when the mean amount of horizontal solar radiation is obtained in January, April, July and October. In addition, it is found the optimum tilt angle of solar panel installed on the roof of the buildings should be 0 degree, i.e., placed horizontally.展开更多
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...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<sup>−</sup><sup>1</sup>) 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<sup>−</sup><sup>1</sup> plots exhibiting the lowest and highest grain yields of 1238 kg∙ha<sup>−</sup><sup>1</sup> and 2098 kg∙ha<sup>−</sup><sup>1</sup>, respectively. Variety and nitrogen effects on partial factor productivity (PFP<sub>N</sub>), 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 PFP<sub>N</sub> (41.3 kg grain kg<sup>−</sup><sup>1</sup>∙N) and AEN (29.4 kg grain kg<sup>−</sup><sup>1</sup>∙N) were obtained in the 30 kg∙N∙ha<sup>−</sup><sup>1</sup> plots, while the highest VCR (2.8) and MR (SLL 1.8 SLL<sup>−</sup><sup>1</sup> spent on N) were obtained in the 180 kg∙N∙ha<sup>−</sup><sup>1</sup>. 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.展开更多
In China’s countryside today, so far the foodstuffs for daily-life subsistence are still taken from the traditional farming production in addition to the yield of animal husbandry, while crop plantation takes the lio...In China’s countryside today, so far the foodstuffs for daily-life subsistence are still taken from the traditional farming production in addition to the yield of animal husbandry, while crop plantation takes the lion’s share in our rural economy. During the Medieval Age of the Western countries, however, special stress was placed on raising livestock on pastureland until the Industrial Revolution occurred in the 18th century when grain-oriented agriculture came into being. As a result of the unprecedented boom of modern science and technology now sweeping the whole world, farming productivity has sky-展开更多
With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during gra...With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during grain filling, and theirrelationships with the filling rate, gel consistency (GC), alkali spreading value (ASV) and amylose content (AC) werestudied. The results showed that changes in activities of ADPGPase, SSase and Q-enzyme exhibited a single peak duringgrain filling, and the time of the activity peaks for the former two enzymes was earlier than that of the maximum grain-fillingrate (Tmax), and the time reaching the peak for Q-enzyme was synchronous with Tmax. The activities at early grain fillingstage, and the mean and maximum activities of each enzyme during grain filling period were positively and significantly orvery significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in the grains.Activities of ADPGPase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were notsignificantly correlated the cooking quality (GC, ASV and AC). SSase activities at the early filling stage were significantlyand negatively correlated with GC and ASV, and positively correlated with AC. Activities of SSase at mid and late grainfilling stages and Q-enzyme at the late filling stage were significantly and positively correlated with GC and ASV, andnegatively correlated with AC. Spraying zeatin or abscisic acid at early grain filling stage could obviously regulate theactivities of ADPGPase, SSase and Q-enzyme in the grains.展开更多
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...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.展开更多
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...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.展开更多
High temperature(HT)during grain filling is one of the most important environmental factors limiting maize yield and grain quality.Nitrogen(N)fertilizer is essential for maintaining normal plant growth and defense aga...High temperature(HT)during grain filling is one of the most important environmental factors limiting maize yield and grain quality.Nitrogen(N)fertilizer is essential for maintaining normal plant growth and defense against environmental stresses.The effects of three N rates and two temperature regimes on the grain yield and quality of fresh waxy maize were studied using the hybrids Suyunuo 5(SYN5)and Yunuo 7(YN7)as materials.N application rates were 1.5,4.5,and 7.5 g plant-1,representing low,moderate,and high N levels(LN,MN,and HN,respectively).Mean day/night temperatures during the grain filling of spring-and summer-sown plants were 27.6/21.0°C and 28.6/20.0°C for ambient temperature(AT)and 35/21.0°C and 35/20.0°C for HT,respectively.On average,HT reduced kernel number,weight,yield,and moisture content by 29.8%,17.9%,38.7%,and 3.3%,respectively.Kernel number,weight,yield,moisture,and starch contents were highest under MN among the three N rates under both temperature regimes.HT reduced grain starch content at all N levels.HT increased grain protein content,which gradually increased with N rate.Mean starch granule size under MN was larger(10.9μm)than that under LN and HN(both 10.4μm)at AT.However,the mean size of starch granules was higher under LN(11.7μm)and lower under MN(11.2μm)at HT.Iodine binding capacity(IBC)was lowest under MN and highest under HN among the three N levels under both temperature regimes.In general,IBC at all N rates was increased by HT.Peak viscosity(PV)was gradually reduced with increasing N rate at AT.In comparison with LN,PV was increased by MN and decreased by HN at HT.Retrogradation percentage gradually increased with N rate at AT,but was lowest under MN among the three N rates at HT.LN+AT and MN+HT produced grain with high pasting viscosity and low retrogradation tendency.MN application could alleviate the negative effects of HT on the grain yield and quality of fresh waxy maize.展开更多
Molecular dynamics simulations of nanocrystalline Cu with average grain sizes of 3.1 nm, 6.2 nm, 12.4 nm and 18.6 nm under uniaxial strain and stress tension at strain rates of 10^8 s^-1, 10^9 S^-1 and 10^10 s^-1 are ...Molecular dynamics simulations of nanocrystalline Cu with average grain sizes of 3.1 nm, 6.2 nm, 12.4 nm and 18.6 nm under uniaxial strain and stress tension at strain rates of 10^8 s^-1, 10^9 S^-1 and 10^10 s^-1 are performed to study the combined grain size, strain rate and loading condition effects on mechanical properties. It is found that the strength of nanocrystalline Cu increases as grain size increases regardless of loading condition. Both the strength and ductility of nanocrystalline Cu increase with strain rate except that there is no monotonic relation between the strength and strain rate for specimens under uni- axial strain loading. Moreover, the strength and ductility of specimens under uniaxial strain loading are lower than those under uniaxial stress loading. The nucleation of voids at grain boundaries and their subsequent growth characterize the failure of specimens under uniaxial strain loading, while grain boundary sliding and necking dominate the failure of specimens under uniaxial stress loading. The rate dependent strength is mainly caused by the dynamic wave effect that limits dislocation motion, while combined twinning and slipping mechanism makes the material more ductile at higher strain rates.展开更多
Mg-1.0Al-1.0Ca-0.4Mn(AXM1104, wt.%) low alloy was extruded at 200 ℃ with an extrusion ratio of 25 and different ram speeds from 1.0 to 7.0 mm/s. The influence of extrusion rate on microstructure and mechanical proper...Mg-1.0Al-1.0Ca-0.4Mn(AXM1104, wt.%) low alloy was extruded at 200 ℃ with an extrusion ratio of 25 and different ram speeds from 1.0 to 7.0 mm/s. The influence of extrusion rate on microstructure and mechanical properties of the AXM1104 alloy was systematically studied. With the increasing of extrusion rate, the mean dynamically recrystallized(DRXed) grain size of the low alloy and average particles diameter of precipitate second phases were increased, while the degree of grain boundary segregation and the intensity of the basal fiber texture were decreased. With the rising of extrusion rate from 1.0 to 7.0 mm/s, the tensile yield strength(TYS) of the as-extruded AXM1104 alloy was decreased from 445 MPa to 249 MPa, while the elongation to failure(EL) was increased from 5.0% to 17.6%. The TYS, ultimate tensile strength(UTS) and EL of the AXM1104 alloy extruded at the ram speed of 1.5 mm/s was 412 MPa, 419 MPa and 12.0%, respectively,exhibiting comprehensive tensile mechanical properties with ultra-high strength and excellent plasticity. The ultra-high TYS of 412 MPa was mainly due to the strengthening from ultra-fine DRXed grains with segregation of solute atoms at grain boundaries. The strain hardening rate is increase slightly with increasing extrusion speed, which may be ascribed to the increasing mean DRXed grain size with rising extrusion speed. The higher strain hardening rate contributes to the higher EL of these AXM1104 samples extruded at higher ram speed.展开更多
This far stern difficulhes and challenges fatal by the dev ofadn P in etna. to the bac national snon of China and the of and min the world market, China must meet the and Inainly by her own production. Using the input...This far stern difficulhes and challenges fatal by the dev ofadn P in etna. to the bac national snon of China and the of and min the world market, China must meet the and Inainly by her own production. Using the input output and system edence metal, this makesa foast abbot China’s glain output, grain and allsupport rate in the year 2030.展开更多
A rapid-heating method in the absence of electric/magnetic field was achieved by introducing a self-propagating-combustion (SHS) as heating source. The effect of heating rate on the alumina grain growth was explored...A rapid-heating method in the absence of electric/magnetic field was achieved by introducing a self-propagating-combustion (SHS) as heating source. The effect of heating rate on the alumina grain growth was explored based on this rapid-heating method. Comparing with the alumina prepared by two different heating ratios (greater than 1 000 ℃/min in SItS and about 50 ℃/min in common pressureless sintering furnace), it was revealed that the rapid heating could promote the grain growth greatly without pressure during sintering. However, if a pressure was applied simultaneously, the grain growth would be almost completely restrained. Since these observations are quite different from the expectation, a new grain growth model was proposed.展开更多
Dense planting could be a feasible method for reducing nitrogen(N) application rates without compromising rice grain yield in northeast and central China. It is still unclear whether reduced N application with dense p...Dense planting could be a feasible method for reducing nitrogen(N) application rates without compromising rice grain yield in northeast and central China. It is still unclear whether reduced N application with dense planting(RNDP) can achieve higher rice yield and N use efficiency(NUE) in Jiangsu, east China. Three japonica inbred rice(JI) and three indica hybrid rice(IH) cultivars were grown in a field experiment. Their grain yield, NUE, and related traits were compared under two cultivation treatments:conventional high-yielding practice(CHYP) and RNDP. JI showed similar yields under the two treatments,while IH showed lower yield under RNDP than under CHYP, and the partial factor productivity of N and N use efficiency for grain yield increased(P < 0.05) in both JI and IH under RNDP. Compared with CHYP,RNDP reduced spikelets per panicle but increased panicles per m2 and filled-kernel percentage of JI and IH, and JI's kernel weight was increased(P < 0.05) under RNDP. Shoot biomass weight and nonstructural carbohydrate(NSC) content in the stem at heading and maturity of JI and IH were reduced under RNDP, while harvest index and NSC remobilization reserve were increased(P < 0.05) under RNDP, especially for JI. Our results suggest that RNDP could achieve a higher rice grain yield and NUE, particularly for JI, a dominant rice cultivar type in Jiangsu. For JI, the increased panicles per m2, sink-filling efficiency, harvest index, and NSC remobilization after heading under RNDP contributed to a grain yield similar to that under CHYP.展开更多
The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However,little attention has been paid to the growth process of the emerging metropolitan are...The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However,little attention has been paid to the growth process of the emerging metropolitan area situated in major grain producing locations in the central China.Taking the Zhengzhou metropolitan area(ZZMA)as a case study,we developed an inverse S-shape model to characterize the spatial distribution of urban land density,and constructed an urban expansion core index,urban expansion intensity index,and urban compactness index to quantify the spatial structure change that has taken place from 1978 to 2017 during the process of urban expansion.Moreover,cropland contribution rate(CR)was constructed to evaluate the impacts of urban expansion on croplands.We uncovered four key findings.First,over the past 40 yr,the ZZMA has experienced dramatic expansion,and the central city of Zhengzhou expanded faster than other cities.The gravity centers of urban expansion of surrounding cities were moving toward to Zhengzhou City.Second,the urban land density decreased with the distance from the city center to the outskirts.As the only large city,Zhengzhou has experienced the fastest and most compact centralized urban expansion,especially after 2000,while other medium-and small-sized cities have experienced low-intensity decentralized expansion.Third,the urban core has been gradually expanding outward.From 1978 to 2017,the hot-zone of urban growth has moved progressively with the acceleration of urbanization.All cities except Jiaozuo had a single peak in different periods.Forth,the cities in national core grain-producing areas has higher cropland contribution rates and lower urban expansion areas,which was closely related to cropland protection.Further analysis showed that large city was relatively better positioned than smaller cities in the efficiency of their urban infrastructure and the effectiveness of wealth creation efficiency in the urbanized area could be tested in all cities,and the policy factor seemed to play an important role in the urban expansion process.展开更多
Increased plant density with low N rate was a recommended strategy to increase grain yield and N use efficiency(NUE);however,grain yield,NUE and the total N uptake(TNU)responses of hybrid rice to this strategy at diff...Increased plant density with low N rate was a recommended strategy to increase grain yield and N use efficiency(NUE);however,grain yield,NUE and the total N uptake(TNU)responses of hybrid rice to this strategy at different yield levels(medium yielding site(MYS)Luzhou City and high yielding site(HYS)Deyang City had not been described.Field experiments with hybrid rice Rongyou1015 were conducted to study the effects of two plant densities.High plant density(HD),low plant density(LD)and four N rates(without N,N_(0);a recommended N rate of 195 kg•hm^(-2),N_(CK);a 23%reduction in N rate,N_(-23%);a 46%reduction in N rate,N_(-46%)on yield attributes,grain yield,TNU and NUE of hybrid rice were studied under different yield levels in 2016-2017.The results showed that the grain yield and NUE of hybrid rice in response to plant density and N rate varied with yield levels.For MYS,reducing N rate by 46%result in significantly lower grain yield at LD treatment;whereas at HD treatment the grain yield of hybrid rice under N_(-46%) and N_(CK) were equal.For HYS,reducing N rate by 46% result in significantly lower grain yield regardless of low plant density and high plant density;however,a reduction in N rate by 23%increased grain yield,AE_(N) by 36%,PFP_(N) by 31% and RE_(N) by 11% over N_(CK) at HD treatment.Higher grain yield of hybrid rice under the combination of HD with low N rate was attributable to improvement in spikelets per panicle and harvest index.The results suggested that high plant density with low N rate might be an effective approach to improve grain yield and NUE in rice production,but reduction in N application rate was determined,according to yield levels.展开更多
<span style="font-family:Verdana;">A field trial was conducted at a private farm in AL-Hashimiya district Babylon Governorate—the republic of Iraq during the 2016</span><span style="font...<span style="font-family:Verdana;">A field trial was conducted at a private farm in AL-Hashimiya district Babylon Governorate—the republic of Iraq during the 2016</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">2017 and 2017</span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">2018 growing seasons.</span><span style="color:red;"> </span><span style="font-family:Verdana;">This study was conducted using two irrigation methods, sprinkler and surface irrigation, for each of them had three Tillage methods (zero-tillage</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> medium-tillage</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> deep-tillage) and each tillage system had four seeding rate of wheat yield (120</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">180</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">240</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">300) kg<span style="white-space:nowrap;">∙</span>ha</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Results indicated that the consumptive water use was 557.5 and</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">535.9 mm for surface irrigation and 460.9 and 442.6 mm for sprinkler irrigation in </span><span style="font-family:Verdana;">the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">2016-2017 and 2017-2018 growing seasons. Sprinkler irrigation significantly increased the flag leaf area with no significant effect on plant height. However, the minimum tillage and seeding rate (240 kg<span style="white-space:nowrap;">∙</span>ha</span><sup><span style="font-family:Verdana;">-1</span></sup></span><span style="font-family:;" "=""><span style="font-family:Verdana;">) significantly increased the plant height and flag leaf </span><span style="font-family:Verdana;">area in both growing seasons. For the grain yield, the sprinkler irrigation, m</span><span style="font-family:Verdana;">inimum tillage, and seeding rate (240 </span></span><span style="font-family:;" "=""><span style="font-family:Verdana;">kg<span style="white-space:nowrap;">∙</span>ha</span><sup><span style="font-family:Verdana;">-1</span></sup></span><span style="font-family:;" "=""><span style="font-family:Verdana;">) also increased the plant height and flag leaf area by 13%, 10, % 11%, 11%, 12%, and 14% in both growing seasons, respectively, through an increased number of spikes/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, the number of grain spike-1, and 1000-grain weight in both growing seasons, respe</span></span><span style="font-family:Verdana;">ctively. Interestingly the grain yield was increased by 33% and 32% in both growing seasons under the effects of these three factors altogether, respectively. It can be concluded that these factors act synergistically, resulting in a significant improvement in the wheat grain-yield of, less consumptive water use, and high water use efficiency.</span>展开更多
An extruded Mg-6Gd-3Y-1.5Ag(wt%) alloy was processed by 6 passes of equal channel angular pressing(ECAP) at 553 K using route Bc to refine the microstructure. Electron back-scattered diffraction(EBSD) analysis showed ...An extruded Mg-6Gd-3Y-1.5Ag(wt%) alloy was processed by 6 passes of equal channel angular pressing(ECAP) at 553 K using route Bc to refine the microstructure. Electron back-scattered diffraction(EBSD) analysis showed a fully recrystallized microstructure for the extruded alloy with a mean grain size of 8.6 μm. The microstructure of the ECAP-processed alloy was uniformly refined through dynamic recrystallization(DRX). This microstructure contained fine grains with an average size of 1.3 μm, a high fraction of high angle grain boundaries(HAGBs), and nano-sized Mg_(5)Gd-type particles at the boundaries of the DRXed grains, detected by transmission electron microscopy(TEM). High-temperature shear punch testing(SPT) was used to evaluate the superplastic behavior of both the extruded and ECAP-processed alloys by measuring the strain rate sensitivity(SRS) index(m-value). While the highest m-value for the extruded alloy was measured to be 0.24 at 673 K, the ECAP-processed alloy exhibited much higher m-values of 0.41 and 0.52 at 598 and 623 K, respectively,delineating the occurrence of superplastic flow. Based on the calculated average activation energy of 118 kJ mol^(-1) and m-values close to 0.5, the deformation mechanism for superplastic flow at the temperatures of 598 and 623 K for the ECAP-processed alloys was recognized to be grain boundary sliding(GBS) assisted by grain boundary diffusion.展开更多
The effect of vibration(50 Hz)on the formation of aluminum castings of 99.5%purity at various cooling rates was studied.It was found that the presence of vibration leads to an increase in the cooling rate of the casti...The effect of vibration(50 Hz)on the formation of aluminum castings of 99.5%purity at various cooling rates was studied.It was found that the presence of vibration leads to an increase in the cooling rate of the castings.It was found that the higher the speed without vibration,the stronger the effect of increasing the speed when vibration was applied.Apparently,this effect is associated with additional mixing of the melt by free-floating crystals.展开更多
基金supported by the National Natural Science Foundation of China(31971845 and 32101819)the earmarked fund for China Agriculture Research System(CARS-01-20)the China Postdoctoral Science Foundation(2021M691179)。
文摘Nitrogen(N) and seeding rates are important factors affecting grain yield and N use efficiency(NUE) in directseeded rice. However, these factors have not been adequately investigated on direct-seeded and double-season rice(DDR) in Central China. The objective of this study was to evaluate the effects of various N and seeding rates on the grain yield and NUE of an ultrashort-duration variety grown under DDR. Field experiments were conducted in 2018 in Wuxue County and 2019 in Qichun County, Hubei Province, China with four N rates and three seeding rates.The results showed that the grain yield of the ultrashort-duration variety ranged from 6.32 to 8.23 t ha–1with a total growth duration of 85 to 97 days across all treatments with N application. Grain yield was increased significantly by N application in most cases, but seeding rate had an inconsistent effect on grain yield. Furthermore, the response of grain yield to the N rates was much higher than the response to seeding rates. The moderate N rates of 100–150 and 70–120 kg N ha–1in the early and late seasons, respectively, could fully express the yield potential of the ultrashort-duration variety grown under DDR. Remarkably higher N responses and agronomic NUE levels were achieved in the early-season rice compared with the late-season rice due to the difference in indigenous soil N supply capacity(INS) between the two seasons. Seasonal differences in INS and N response should be considered when crop management practices are optimized for achieving high grain yield and NUE in ultrashort-duration variety grown under DDR.
基金the National Natural Science Foundation of China(32071947,32071944,31871557)the Open Project of Jiangsu Key Laboratory of Crop Genetics and Physiology(YCSL202102)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Postgraduate Research&Practice Innovation Program of Jiangsu province(KYCX21_3235).
文摘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.
文摘A building integrated photovoltaic (PV) and fuel cell (FC) system is proposed for assessment of the energy self-sufficiency rate in a city in Japan. The electricity consumed in the building is mainly supplied by solar panels, while the gap between the energy demand and supply is solved by the FC that is powered by the H2 produced by water electrolysis with surplus power of PV. A desktop case study of using the proposed system in Tsu city which is located in central part of Japan, has been conducted. The results found that the self-sufficiency rates of PV system to electricity demand of households (RPV) during the daytime in April and July are higher than those in January and October. The results also reveal that the self-sufficiency rate of FC system to the electricity demand (RFC) is 15% - 38% for the day when the mean amount of horizontal solar radiation is obtained in January, April, July and October. In addition, it is found the optimum tilt angle of solar panel installed on the roof of the buildings should be 0 degree, i.e., placed horizontally.
文摘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<sup>−</sup><sup>1</sup>) 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<sup>−</sup><sup>1</sup> plots exhibiting the lowest and highest grain yields of 1238 kg∙ha<sup>−</sup><sup>1</sup> and 2098 kg∙ha<sup>−</sup><sup>1</sup>, respectively. Variety and nitrogen effects on partial factor productivity (PFP<sub>N</sub>), 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 PFP<sub>N</sub> (41.3 kg grain kg<sup>−</sup><sup>1</sup>∙N) and AEN (29.4 kg grain kg<sup>−</sup><sup>1</sup>∙N) were obtained in the 30 kg∙N∙ha<sup>−</sup><sup>1</sup> plots, while the highest VCR (2.8) and MR (SLL 1.8 SLL<sup>−</sup><sup>1</sup> spent on N) were obtained in the 180 kg∙N∙ha<sup>−</sup><sup>1</sup>. 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.
文摘In China’s countryside today, so far the foodstuffs for daily-life subsistence are still taken from the traditional farming production in addition to the yield of animal husbandry, while crop plantation takes the lion’s share in our rural economy. During the Medieval Age of the Western countries, however, special stress was placed on raising livestock on pastureland until the Industrial Revolution occurred in the 18th century when grain-oriented agriculture came into being. As a result of the unprecedented boom of modern science and technology now sweeping the whole world, farming productivity has sky-
基金supported by the National Natural Science Foundation of China(30370828)the Natural Science Foundation of Jiangsu Province,China(BK2003041)
文摘With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during grain filling, and theirrelationships with the filling rate, gel consistency (GC), alkali spreading value (ASV) and amylose content (AC) werestudied. The results showed that changes in activities of ADPGPase, SSase and Q-enzyme exhibited a single peak duringgrain filling, and the time of the activity peaks for the former two enzymes was earlier than that of the maximum grain-fillingrate (Tmax), and the time reaching the peak for Q-enzyme was synchronous with Tmax. The activities at early grain fillingstage, and the mean and maximum activities of each enzyme during grain filling period were positively and significantly orvery significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in the grains.Activities of ADPGPase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were notsignificantly correlated the cooking quality (GC, ASV and AC). SSase activities at the early filling stage were significantlyand negatively correlated with GC and ASV, and positively correlated with AC. Activities of SSase at mid and late grainfilling stages and Q-enzyme at the late filling stage were significantly and positively correlated with GC and ASV, andnegatively correlated with AC. Spraying zeatin or abscisic acid at early grain filling stage could obviously regulate theactivities of ADPGPase, SSase and Q-enzyme in the grains.
基金supported by grants from the National Natural Science Foundation of China(No.31301279)National Basic Research Program of China(No.2015CB150404)+1 种基金the National Key Technology R&D Program of China(No.2011BAD16B14)the Innovation Program of Heilongjiang Academy of Agricultural Sciences
文摘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.
基金supported by the Ministry of Agriculture of China(Grant No.2005-2009)
文摘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.
基金supported by the National Key Research and Development Program of China(2016YFD0300109,2018YFD0200703)the National Natural Science Foundation of China(31771709)+2 种基金Jiangsu Agriculture Science and Technology Innovation Fund(CX[19]3056)the Priority Academic Program Development of Jiangsu Higher Education InstitutionsHigh-end Talent Support Program of Yangzhou University。
文摘High temperature(HT)during grain filling is one of the most important environmental factors limiting maize yield and grain quality.Nitrogen(N)fertilizer is essential for maintaining normal plant growth and defense against environmental stresses.The effects of three N rates and two temperature regimes on the grain yield and quality of fresh waxy maize were studied using the hybrids Suyunuo 5(SYN5)and Yunuo 7(YN7)as materials.N application rates were 1.5,4.5,and 7.5 g plant-1,representing low,moderate,and high N levels(LN,MN,and HN,respectively).Mean day/night temperatures during the grain filling of spring-and summer-sown plants were 27.6/21.0°C and 28.6/20.0°C for ambient temperature(AT)and 35/21.0°C and 35/20.0°C for HT,respectively.On average,HT reduced kernel number,weight,yield,and moisture content by 29.8%,17.9%,38.7%,and 3.3%,respectively.Kernel number,weight,yield,moisture,and starch contents were highest under MN among the three N rates under both temperature regimes.HT reduced grain starch content at all N levels.HT increased grain protein content,which gradually increased with N rate.Mean starch granule size under MN was larger(10.9μm)than that under LN and HN(both 10.4μm)at AT.However,the mean size of starch granules was higher under LN(11.7μm)and lower under MN(11.2μm)at HT.Iodine binding capacity(IBC)was lowest under MN and highest under HN among the three N levels under both temperature regimes.In general,IBC at all N rates was increased by HT.Peak viscosity(PV)was gradually reduced with increasing N rate at AT.In comparison with LN,PV was increased by MN and decreased by HN at HT.Retrogradation percentage gradually increased with N rate at AT,but was lowest under MN among the three N rates at HT.LN+AT and MN+HT produced grain with high pasting viscosity and low retrogradation tendency.MN application could alleviate the negative effects of HT on the grain yield and quality of fresh waxy maize.
基金financial support from Australian Research Council(ARC)Centre of Excellence for Design in Light Metals
文摘Molecular dynamics simulations of nanocrystalline Cu with average grain sizes of 3.1 nm, 6.2 nm, 12.4 nm and 18.6 nm under uniaxial strain and stress tension at strain rates of 10^8 s^-1, 10^9 S^-1 and 10^10 s^-1 are performed to study the combined grain size, strain rate and loading condition effects on mechanical properties. It is found that the strength of nanocrystalline Cu increases as grain size increases regardless of loading condition. Both the strength and ductility of nanocrystalline Cu increase with strain rate except that there is no monotonic relation between the strength and strain rate for specimens under uni- axial strain loading. Moreover, the strength and ductility of specimens under uniaxial strain loading are lower than those under uniaxial stress loading. The nucleation of voids at grain boundaries and their subsequent growth characterize the failure of specimens under uniaxial strain loading, while grain boundary sliding and necking dominate the failure of specimens under uniaxial stress loading. The rate dependent strength is mainly caused by the dynamic wave effect that limits dislocation motion, while combined twinning and slipping mechanism makes the material more ductile at higher strain rates.
基金supported by National Natural Science Foundation of China (No. 51971076 and No. 51771062)。
文摘Mg-1.0Al-1.0Ca-0.4Mn(AXM1104, wt.%) low alloy was extruded at 200 ℃ with an extrusion ratio of 25 and different ram speeds from 1.0 to 7.0 mm/s. The influence of extrusion rate on microstructure and mechanical properties of the AXM1104 alloy was systematically studied. With the increasing of extrusion rate, the mean dynamically recrystallized(DRXed) grain size of the low alloy and average particles diameter of precipitate second phases were increased, while the degree of grain boundary segregation and the intensity of the basal fiber texture were decreased. With the rising of extrusion rate from 1.0 to 7.0 mm/s, the tensile yield strength(TYS) of the as-extruded AXM1104 alloy was decreased from 445 MPa to 249 MPa, while the elongation to failure(EL) was increased from 5.0% to 17.6%. The TYS, ultimate tensile strength(UTS) and EL of the AXM1104 alloy extruded at the ram speed of 1.5 mm/s was 412 MPa, 419 MPa and 12.0%, respectively,exhibiting comprehensive tensile mechanical properties with ultra-high strength and excellent plasticity. The ultra-high TYS of 412 MPa was mainly due to the strengthening from ultra-fine DRXed grains with segregation of solute atoms at grain boundaries. The strain hardening rate is increase slightly with increasing extrusion speed, which may be ascribed to the increasing mean DRXed grain size with rising extrusion speed. The higher strain hardening rate contributes to the higher EL of these AXM1104 samples extruded at higher ram speed.
文摘This far stern difficulhes and challenges fatal by the dev ofadn P in etna. to the bac national snon of China and the of and min the world market, China must meet the and Inainly by her own production. Using the input output and system edence metal, this makesa foast abbot China’s glain output, grain and allsupport rate in the year 2030.
基金Funded by the National Natural Science Foundation of China(No.U12301013)the State Ministry of Science and Technology Innovation Fund(No.0102010DFA52240)
文摘A rapid-heating method in the absence of electric/magnetic field was achieved by introducing a self-propagating-combustion (SHS) as heating source. The effect of heating rate on the alumina grain growth was explored based on this rapid-heating method. Comparing with the alumina prepared by two different heating ratios (greater than 1 000 ℃/min in SItS and about 50 ℃/min in common pressureless sintering furnace), it was revealed that the rapid heating could promote the grain growth greatly without pressure during sintering. However, if a pressure was applied simultaneously, the grain growth would be almost completely restrained. Since these observations are quite different from the expectation, a new grain growth model was proposed.
基金financed by the National Natural Science Foundation of China(31901448)the Key Research and Development Program of Jiangsu(BE2019343)+4 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJB210004)China Postdoctoral Science Foundation(2020M671628,2020M671629)Jiangsu Postdoctoral Science Foundation(2020Z061)the Guizhou Science and Technology Department(20161148)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Dense planting could be a feasible method for reducing nitrogen(N) application rates without compromising rice grain yield in northeast and central China. It is still unclear whether reduced N application with dense planting(RNDP) can achieve higher rice yield and N use efficiency(NUE) in Jiangsu, east China. Three japonica inbred rice(JI) and three indica hybrid rice(IH) cultivars were grown in a field experiment. Their grain yield, NUE, and related traits were compared under two cultivation treatments:conventional high-yielding practice(CHYP) and RNDP. JI showed similar yields under the two treatments,while IH showed lower yield under RNDP than under CHYP, and the partial factor productivity of N and N use efficiency for grain yield increased(P < 0.05) in both JI and IH under RNDP. Compared with CHYP,RNDP reduced spikelets per panicle but increased panicles per m2 and filled-kernel percentage of JI and IH, and JI's kernel weight was increased(P < 0.05) under RNDP. Shoot biomass weight and nonstructural carbohydrate(NSC) content in the stem at heading and maturity of JI and IH were reduced under RNDP, while harvest index and NSC remobilization reserve were increased(P < 0.05) under RNDP, especially for JI. Our results suggest that RNDP could achieve a higher rice grain yield and NUE, particularly for JI, a dominant rice cultivar type in Jiangsu. For JI, the increased panicles per m2, sink-filling efficiency, harvest index, and NSC remobilization after heading under RNDP contributed to a grain yield similar to that under CHYP.
基金Under the auspices of National Natural Science Foundation of China(No.41971274)the Innovation Research Team of Henan Provincial University(No.2021-CXTD-08,2022-CXTD-02)the Scientific and Technological Innovation Team of Universities in Henan Province(No.22IRTSTHN008)。
文摘The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However,little attention has been paid to the growth process of the emerging metropolitan area situated in major grain producing locations in the central China.Taking the Zhengzhou metropolitan area(ZZMA)as a case study,we developed an inverse S-shape model to characterize the spatial distribution of urban land density,and constructed an urban expansion core index,urban expansion intensity index,and urban compactness index to quantify the spatial structure change that has taken place from 1978 to 2017 during the process of urban expansion.Moreover,cropland contribution rate(CR)was constructed to evaluate the impacts of urban expansion on croplands.We uncovered four key findings.First,over the past 40 yr,the ZZMA has experienced dramatic expansion,and the central city of Zhengzhou expanded faster than other cities.The gravity centers of urban expansion of surrounding cities were moving toward to Zhengzhou City.Second,the urban land density decreased with the distance from the city center to the outskirts.As the only large city,Zhengzhou has experienced the fastest and most compact centralized urban expansion,especially after 2000,while other medium-and small-sized cities have experienced low-intensity decentralized expansion.Third,the urban core has been gradually expanding outward.From 1978 to 2017,the hot-zone of urban growth has moved progressively with the acceleration of urbanization.All cities except Jiaozuo had a single peak in different periods.Forth,the cities in national core grain-producing areas has higher cropland contribution rates and lower urban expansion areas,which was closely related to cropland protection.Further analysis showed that large city was relatively better positioned than smaller cities in the efficiency of their urban infrastructure and the effectiveness of wealth creation efficiency in the urbanized area could be tested in all cities,and the policy factor seemed to play an important role in the urban expansion process.
基金Supported by Earmarked Fund for Modern Agro-industry Technology of China(CARS-01-25)National Key Research and Development Program of China(2017YFD0301705)Foundation of Youth Science Program of Sichuan Agricultural Sciences Academy(2019QNJJ-020)。
文摘Increased plant density with low N rate was a recommended strategy to increase grain yield and N use efficiency(NUE);however,grain yield,NUE and the total N uptake(TNU)responses of hybrid rice to this strategy at different yield levels(medium yielding site(MYS)Luzhou City and high yielding site(HYS)Deyang City had not been described.Field experiments with hybrid rice Rongyou1015 were conducted to study the effects of two plant densities.High plant density(HD),low plant density(LD)and four N rates(without N,N_(0);a recommended N rate of 195 kg•hm^(-2),N_(CK);a 23%reduction in N rate,N_(-23%);a 46%reduction in N rate,N_(-46%)on yield attributes,grain yield,TNU and NUE of hybrid rice were studied under different yield levels in 2016-2017.The results showed that the grain yield and NUE of hybrid rice in response to plant density and N rate varied with yield levels.For MYS,reducing N rate by 46%result in significantly lower grain yield at LD treatment;whereas at HD treatment the grain yield of hybrid rice under N_(-46%) and N_(CK) were equal.For HYS,reducing N rate by 46% result in significantly lower grain yield regardless of low plant density and high plant density;however,a reduction in N rate by 23%increased grain yield,AE_(N) by 36%,PFP_(N) by 31% and RE_(N) by 11% over N_(CK) at HD treatment.Higher grain yield of hybrid rice under the combination of HD with low N rate was attributable to improvement in spikelets per panicle and harvest index.The results suggested that high plant density with low N rate might be an effective approach to improve grain yield and NUE in rice production,but reduction in N application rate was determined,according to yield levels.
文摘<span style="font-family:Verdana;">A field trial was conducted at a private farm in AL-Hashimiya district Babylon Governorate—the republic of Iraq during the 2016</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">2017 and 2017</span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""><span style="font-family:Verdana;">2018 growing seasons.</span><span style="color:red;"> </span><span style="font-family:Verdana;">This study was conducted using two irrigation methods, sprinkler and surface irrigation, for each of them had three Tillage methods (zero-tillage</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> medium-tillage</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> deep-tillage) and each tillage system had four seeding rate of wheat yield (120</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">180</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">240</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">300) kg<span style="white-space:nowrap;">∙</span>ha</span><sup><span style="font-family:Verdana;">-1</span></sup><span style="font-family:Verdana;">.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Results indicated that the consumptive water use was 557.5 and</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">535.9 mm for surface irrigation and 460.9 and 442.6 mm for sprinkler irrigation in </span><span style="font-family:Verdana;">the </span><span style="font-family:;" "=""><span style="font-family:Verdana;">2016-2017 and 2017-2018 growing seasons. Sprinkler irrigation significantly increased the flag leaf area with no significant effect on plant height. However, the minimum tillage and seeding rate (240 kg<span style="white-space:nowrap;">∙</span>ha</span><sup><span style="font-family:Verdana;">-1</span></sup></span><span style="font-family:;" "=""><span style="font-family:Verdana;">) significantly increased the plant height and flag leaf </span><span style="font-family:Verdana;">area in both growing seasons. For the grain yield, the sprinkler irrigation, m</span><span style="font-family:Verdana;">inimum tillage, and seeding rate (240 </span></span><span style="font-family:;" "=""><span style="font-family:Verdana;">kg<span style="white-space:nowrap;">∙</span>ha</span><sup><span style="font-family:Verdana;">-1</span></sup></span><span style="font-family:;" "=""><span style="font-family:Verdana;">) also increased the plant height and flag leaf area by 13%, 10, % 11%, 11%, 12%, and 14% in both growing seasons, respectively, through an increased number of spikes/m</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, the number of grain spike-1, and 1000-grain weight in both growing seasons, respe</span></span><span style="font-family:Verdana;">ctively. Interestingly the grain yield was increased by 33% and 32% in both growing seasons under the effects of these three factors altogether, respectively. It can be concluded that these factors act synergistically, resulting in a significant improvement in the wheat grain-yield of, less consumptive water use, and high water use efficiency.</span>
文摘An extruded Mg-6Gd-3Y-1.5Ag(wt%) alloy was processed by 6 passes of equal channel angular pressing(ECAP) at 553 K using route Bc to refine the microstructure. Electron back-scattered diffraction(EBSD) analysis showed a fully recrystallized microstructure for the extruded alloy with a mean grain size of 8.6 μm. The microstructure of the ECAP-processed alloy was uniformly refined through dynamic recrystallization(DRX). This microstructure contained fine grains with an average size of 1.3 μm, a high fraction of high angle grain boundaries(HAGBs), and nano-sized Mg_(5)Gd-type particles at the boundaries of the DRXed grains, detected by transmission electron microscopy(TEM). High-temperature shear punch testing(SPT) was used to evaluate the superplastic behavior of both the extruded and ECAP-processed alloys by measuring the strain rate sensitivity(SRS) index(m-value). While the highest m-value for the extruded alloy was measured to be 0.24 at 673 K, the ECAP-processed alloy exhibited much higher m-values of 0.41 and 0.52 at 598 and 623 K, respectively,delineating the occurrence of superplastic flow. Based on the calculated average activation energy of 118 kJ mol^(-1) and m-values close to 0.5, the deformation mechanism for superplastic flow at the temperatures of 598 and 623 K for the ECAP-processed alloys was recognized to be grain boundary sliding(GBS) assisted by grain boundary diffusion.
基金This work was supported by the National Academy of Sciences of Ukraine under Grants#III-21-18-685 and#III-36-21-708.
文摘The effect of vibration(50 Hz)on the formation of aluminum castings of 99.5%purity at various cooling rates was studied.It was found that the presence of vibration leads to an increase in the cooling rate of the castings.It was found that the higher the speed without vibration,the stronger the effect of increasing the speed when vibration was applied.Apparently,this effect is associated with additional mixing of the melt by free-floating crystals.