The Grain-population Relationship and the Effect of Main Food Producing Areas in China

With the increase of global population,grain-population relationship has attracted great attention worldwide.In China,grain-population relationship has become an increasingly important economic concern.Of central importance to the food security debate in China is the geography of grain supply and demand.This paper uses a grain demand and supply index (DSR) to analyze the spatial-temporal relationship between population and grain in China from 1949 to 2007 at national and provincial scales.The results are examined in three periods.(1) From 1949 to 2007,with the increase of grain production,the relationship between population and grain of China improved considerably.(2) Over the past 35 years (1970-2005),on the whole the grain producing areas have had grain surplus and contributed to the nation by providing grain,but the ability to provide sufficient grain is not stable.(3) Over the past 15 years (1990-2005),decreases in planting area brought pressure on national grain food security.The paper concludes that the key to providing more food for the main food producing provinces is increasing yield on the basis of steady plant area.

Evolution of the North Atlantic Current and Barents Ice Sheet as revealed by grain size populations in the northern Norwegian Sea during the last 60 ka

The grain size distribution of bulk sediment samples was decomposed in a core to reconstruct paleoceanographic evolution over the past 60 ka in the northern Norwegian Sea.The results show that sediments consisted of 3–4 grain populations derived from the North Atlantic Current(NAC)and Barents Ice Sheet(BIS).The grain size data suggest three palaeoceanographic evolution stages:(1)an environment affected by BIS and NAC and changed with the interstadial/stadial transition in phase with the Greenland ice-core record at 60–31 ka BP,during which discharge of icebergs and the content of the coarsest population containing ice-rafted debris(IRD)in the sediments increased significantly during stadial,while the fine silt population containing volcanic glasses increased with the enhancement of NAC during the interstadial;(2)an extreme environment controlled by BIS at31–13 ka BP.BIS reached to its maximum at about 31 ka BP and the turbid plumes that formed at the leading edge of BIS contributed to a significant increase in the clayey population in sediments.Icebergs drained into the northern Norwegian Sea with periodical calving of the BIS at 31–19 ka BP.Subsequently,the ablation of the BIS discharged massive floods with clayey sediments and icebergs into the Norwegian Sea at 19–13 ka BP,resulting in a constant increase in clay and IRD in sediments;and(3)a marine environment similar to the present one under the strong influence of NAC following the complete melting of the BIS after 13 ka BP,NAC is the dominant transport agent and no IRD occurred in sediments.The fine silt populations containing volcanic glasses transported by NAC significantly increased.

Effects of Irrigation Schedules on Photosynthetic Carbon Assimilation of Winter Wheat (Triticum aestivum L.) in North China Plain:from Leaf to Population

A field experiment was conducted to elucidate the regulation mechanism of different irrigation schedules on population photosynthetic of winter wheat. The experiment included five irrigation schedules, such as no irrigation （W0）, irrigation once at jointing （W1j） or at booting （W1b）, irrigation twice at jointing and booting （W2）, and irrigation three times at jointing, booting and grain-filling （W3） and three planting densities, such as 180 （D1）, 300 （D2） and 450 （D3） seedlings per square meter. The results indicated that irrigation significantly improved population photosynthesis. The relationship between population photosynthesis and irrigation time/volume was to some extent parabolic. Improvements in population photosynthesis （resulting from more irrigation time/volume） were mainly related to increase in leaf area index and population light interception. Population photosynthesis exhibited a significantly negative correlation with canopy light transmittance. Population photosynthesis at grain filling stage was significantly positively correlated with dry matter accumulation at post-anthesis and grain yield. Main effects and partial correlation analysis showed that population photosynthesis of W0, W1j, W1b and W3 were regulated by canopy light transmittance and leaf area. On the other hand, population photosynthesis of W2 was mainly influenced by flag leaf photosynthetic rate. On this basis, planting 300 seedlings per square meter was the optimum combination. The combination of W2D2 increased population photosynthesis during mid-late growth stages and extended high population photosynthesis duration, which ultimately increased grain yield.

Sediment texture and grain-size implications: the Changjiang subaqueous delta

Sediment cores were collected from the subaqueous delta of the Changjiang Estuary. Sediment grain-size profiles and their fractal dimensions were analyzed, to elucidate responses to long-term sedimentary processes. In addition, the environmental sensitive populations of grain size have been extracted. The sediment cores can be divided into two parts, according to the sedimentary structures present. The upper part （0-12 cm） is interpreted as being the active layer, which is influenced frequently by changes in the short-term hydrodynamic environment. The lower part extends from a depth of 12 cm, to the bottom of the core. The pattern of fluctuation is linked to sediment grain size. Moreover, two grain-size sensitive populations can be identified. The fine sensitive population is 6.0-7.2 μm, which is a similar grain size to the suspended sediment from up-river. The coarse sensitive population varies from 40.7 to 57.5 μm, revealing complex changes. Thus, the riverine inputs from the Changjiang River may be an important source, which contributes to seasonal fluctuations of grain-size distribution, over the area. The sediments, with grain-sizes ranging from 0.9 to 20.3 μm, are characterised by self-similar in the fractal non-scale region. The fraetal dimension is eonsistant with the grain-size parameter varatioins, which could be used as a replacement index to reveal and reconstruct the sedimentary environmental evolution.

The influence of Chinese population policy change on resources and the environment

Universal two-child policy has been implemented since the end of 2015 in China.This policy is anticipated to bring a significant increase in the total population,with profound influences on the resources and environment in the future.This paper analyzes the changing dynamics of urban and rural population,and forecasts urban and rural population from 2016 to 2030 at national and provincial scale using a double log linear regression model.Drawing upon the results of these two predictions,the impact of the population policy change on Chinese resources consumption and environmental pollution are predicted quantitatively.Given the future total population maintains current levels on resources consumption and environmental emission,the additional demand of resources and environment demand for the new population is forecasted and compared against the capacity on supply side.The findings are as follows:after implementing the universal two-child policy,China's grain,energy consumption,domestic water demand,and pollutant emissions are projected to increase at different rates across provinces.To meet the needs arising from future population growth,food and energy self-sufficiency rate will be significantly reduced in the future,while relying more on imports.Stability of the water supply needs to be improved,especially in Beijing,Henan,Jiangsu,Qinghai,and Sichuan where the gap in future domestic water demand is comparatively larger.Environmental protection and associated governing capability are in urgent need of upgrade not least due to the increasing pressure of pollution.

Effects of Farming and Seedling-raising Methods on Population Growth and Grain Yield of Mechanized Transplanting Rice

The effects of farming method, rice variety and seedling-raising method were studied on the population growth quality and grain yield of the mechanized transplanting rice by way of three-factor split plot design. The results showed that the no-tillage mechanical transplanting treatment was poorer than the conventional mechanical transplanting treatment in transplanting quality in general, but the former was similar to the latter in population growth quality. In regard to grain yield, the no-tillage mechanical transplanting treatment was lower than the conventional me- chanical transplanting treatment. Raising both pot-mat seedling and plastic-tray seedling did not make much difference in population growth and grain yield of mechanized transplanting rice, so both of the seedling-raising methods can be adopted according to practical conditions.

县域耕地非农化、非粮化与乡村人口空心化的耦合协调关系——以长江经济带为例

耕地非农化、非粮化的不断扩大严重影响了我国的粮食安全,亟需研究其演变机制和管控措施。基于1990、2000、2010和2020年四期土地覆盖数据和农业劳动力数据,利用耦合协调度模型和探索性时空数据分析(ESTDA)方法,分析了长江经济带县域耕地非农化、非粮化和乡村人口空心化的时空演化特征及其耦合协调关系。结果表明:(1)非农化呈现东高西低的格局,且存在围绕中心城市高值集聚的态势。非粮化则大致呈现出西高东低的倾向,远离大城市的边远县域非粮化程度较高。研究期内非农化和非粮化呈整体加剧趋势,乡村人口空心化程度显著提升。(2)非农化、非粮化和乡村人口空心化之间呈现较强耦合作用,失调区域逐渐扩大。(3)非农化、非粮化和乡村人口空心化耦合协调度存在明显的空间集聚现象并逐渐增强。高值集聚区主要分布在上游地区且数量逐渐减少,低值集聚区分布相对分散。(4)非农化、非粮化和乡村人口空心化耦合协调度具有较强时空动态特征,但县域及其邻域协同变动的比例较高,表明具有较强的局域整合性。

基于SmartGrain软件的小麦NaN_3诱变群体籽粒性状分析

为了解小麦NaN3诱变后代籽粒性状的遗传变异规律,利用高通量表型分析软件SmartGrain对小麦新品种陕农33NaN3诱变群体(M3)籽粒性状进行测量,并进行相关分析、通径分析和主成分分析。结果表明,M3代籽粒性状变异系数表现为千粒重>密度因子>表面积>长宽比>粒宽>圆度>周长>粒长,诱变群体籽粒性状均值除长宽比外均较陕农33不同程度下降。千粒重与籽粒表面积、周长、粒长、粒宽、圆度、密度因子均呈极显著正相关,与长宽比呈极显著负相关。经通径分析,7个籽粒性状对千粒重直接贡献表现为密度因子>粒宽>表面积>周长>长宽比>圆度>粒长,其中,密度因子、粒宽和表面积对千粒重有较大的正效应。主成分分析结果显示,2个主成分(籽粒大小和籽粒形状)累计贡献率达到94.10%,说明2个主成分已经覆盖诱变群体所有籽粒性状的主要变异信息。

播期对不同穗型冬小麦生长及产量的影响

为提高冬小麦产量,开展播期对不同穗型冬小麦生长及产量影响的研究。本研究以大穗型品种‘泰农18’、中穗型品种‘山农18’和多穗型品种‘红地95’为试验材料,设置9月30日、10月10日、10月20日、10月30日4个播期,对不同播期条件下的株高、叶面积指数、茎蘖数、产量及产量三要素进行测定。结果表明,随着播期推迟,‘泰农18’、‘山农18’、‘红地95’的株高呈下降趋势,叶面积指数、单位面积茎蘖数、穗数、穗粒数、千粒重和产量均呈现先上升后下降的趋势。产量在播期为10月10日时最高,分别为9.38 t/hm^(2)、8.94 t/hm^(2)、9.22 t/hm^(2),播期为10月30日时最低,分别为7.26 t/hm^(2)、7.32 t/hm^(2)、7.74 t/hm^(2),比最高处理分别下降22.6%、18.1%、16.1%。通过对3个品种产量和三要素之间的通径分析可知,播期主要影响大穗型品种‘泰农18’的穗粒数,中穗型品种‘山农18’的千粒重,多穗型品种‘红地95’的单位面积穗数。综合比较,3个品种的最适播期均为10月10日,晚播可造成株高、叶面积指数、茎蘖数下降,产量降低。

主销区县域粮食生产托管发展调研与思考——以广东省东源县为例

广东临近港澳,经济发达,是全国最大的粮食主销区,也是传统的双季稻产区。托管是当下广东县域粮食生产的热词,它通过引领农户与托管服务组织对接,破解“无人种稻”难题,使“小农户”接轨“大生产”。农业生产托管没有捷径可走,需要从省内基层实践中提炼经验,总结做法,用工匠精神去打磨产品和服务。东源县作为广东农业生产托管发展较为成熟的地区,其模式、做法具有一定代表性,通过专题调研,发现其依然存在成本高、风险高、门槛高、突破难“三高一难”等发展瓶颈,这也是广东农业生产托管的共性问题。为推动农业生产托管进一步发展,建议从创新组织方式、优化补助门槛、创新金融保险服务、培育服务联合体、强化资源要素配置等方面进行优化。

人口老龄化背景下农业社会化服务提升粮食生产效能的机理与路径

农业社会化服务是解决农村人口老龄化背景下“谁来种粮、谁来种地”问题的关键,也是保障国家粮食安全、推进乡村振兴和实现农业农村现代化的重要力量。不断加快的农村人口老龄化,使粮食生产面临劳动力不足和效能提升乏力的现实困境,但同时也给农业社会化服务带来了巨大市场需求。农业社会化服务实现粮食生产效能提升的逻辑机理在于社会化服务对老龄化劳动的要素替代以及对土地、科技、资本要素的优化配置,从而提升粮食生产能力;通过进一步的分工深化、促进农地集聚和产业协同融合,从而提升粮食生产的效率效益。但是,在提升粮食生产效能过程中,农业社会化服务仍然面临服务供给能力不足、服务的供需衔接不畅、成本收益率低、资金和人才缺乏、农户对土地仍存养老依赖等现实短板。为此,应强化粮食生产类农业社会化服务主体建设、促进粮食生产服务供需两端的有效衔接、推进社会化服务的产业化经营、探索粮食生产与农村养老融合的功能属性以及加强政策支持和科技支撑。从现实国情农情出发补齐服务短板,打造粮食生产的社会服务生产力,进而持续提升粮食生产效能。

Dissecting the Genetic Basis of Grain Shape and Chalkiness Traits in Hybrid Rice Using Multiple Collaborative Populations

Dear Editor Through the efficient use of heterosis, hybrid rice varieties generally have higher grain yield potential than inbred varieties. With the significant advantage in grain yield, over the past 30 years approximately half of China＇s total rice-growing area is planted with rice hybrids. However, grain quality has now become one of the most important targets in hybrid rice breeding for meeting consumer demands. Grain shape and chalkiness are two important components of rice grain quality, in which slender grains （typically, grain length-to-width ratio 〉3） with low chatkiness are preferred by most consumers of hybrid rice.

Grain-filling characteristics and yield differences of maize cultivars with contrasting nitrogen efficiencies

To investigate the effect of nitrogen management on the grain-filling characteristics and yield formation of maize cultivars with contrasting nitrogen efficiencies,and to identify differences in grain-filling characteristics and yield of maize cultivars in response to nitrogen management,a two-year field experiment was conducted in southwest China in2015–2016.The grain-filling rate and duration of the N-inefficient cultivar XY 508 were higher than those of the N-efficient cultivar ZH 311.The 100-kernel weight of XY 508 was significantly higher than that of ZH 311.The kernel number per ear of ZH 311 was significantly higher than that of XY 508,making the population filling rate of ZH 311 significantly higher than that of XY 508.The higher population filling rate of the N-efficient maize cultivar led to a significant yield advantage over the N-inefficient maize cultivar.Nitrogen management effectively improved maize grain yield,but the response of maize cultivars with contrasting nitrogen efficiencies to nitrogen management was inconsistent.A basal fertilizer ratio 60.43%with a topdressing ratio 39.57%effectively increased grainfilling rate,delayed the time to maximum filling rate,prolonged the active filling period and effective grain-filling time,increased the 100-kernel weight,and maintained higher kernels per ear,thereby improving the population filling rate and maximizing the yield advantage of the N-efficient cultivar.A 100%basal fertilizer ratio not only increased the number of kernels per ear,but also maintained high grain filling characteristics to obtain a higher 100-kernel weight and increased the population filling rate,leading to a high grain yield in the N-inefficient cultivar.Thus,the 100%basal fertilizer ratio partially compensated for the deficient grain yield of the N-inefficient cultivar.

China's Land Carrying Capacity Based on Man-grain Relationships

With population growth and increasing pressure on land resources,land carrying capacity(LCC) and food safety have been attracting great attention worldwide.From the point of man-grain relationship and by establishing LCC and land carrying capacity index(LCCI) models,this article firstly analyzes the spatial-temporal dynamics of LCC of China from 1949 to 2005 at county,provincial and national levels.Choosing 2005 as a representative year,this article then evaluates the LCC of 264 pastoral regions(semipastoral regions),663 urban regions and 592 poverty stricken regions of the country.The results show that:(1) from 1949 to 2005,with the increase of grain production,the LCC of China has been improved conspicuously,but due to the rapid population growth,the production can only maintain a low level grain consumption;(2) over the past 25 years(1980-2005),the number of population overloading provinces decreased from 23 to 15 and the mangrain relationship has been improved gradually,but there were more overloading provinces than surplus provinces in China;(3) at county level,there were 1572 overloading counties in 1980 accounting for 68.26% of the total counties of the country and where were 649 million people lived,while in 1990,2000 and 2005,the number of overloading counties were 1066,1133 and 1087 respectively,which shows that the man-grain relationship has been improved obviously during the past 25 years;as for spatial distribution,the surplus counties were mainly concentrated in agriculture developed regions,such as Northeast Plain,North China Plain,middle and lower Reaches of the Yangtze River Plain,and overloading counties were mainly located in regions with poor natural environment and low grain production capacity,such as Northwest China,Tibetan Plateau and Loess Plateau and economically developed urban regions,such as Beijing,Tianjin and Shanghai;(4) animal husbandry improved greatly the LCC of pastoral and semi-pastoral regions,while urban regions were overloading for increasing population pressure and more than half of poverty stricken regions were overloading due to critical natural environment and poor economic conditions.

Fine Mapping of qTGW3-1,a QTL for 1000-Grain Weight on Chromosome 3 in Rice

The QTL qTGW3-1 was located on chromosome 3 of rice （Oryza sativa L.） and associated with the 1 000-grain weight （TGW） according to the result of our earlier study. With the objective of fine mapping of this locus, we developed a F2 population consisting of 3 428 plants derived from the cross between TGW-related near isogenic line DL017 （BC3F4 generation of GSL 156×Nipponbare） and the recurrent parent Nipponbare. Using six microsatellites, this QTL was delimited between RM5477 and RM6417. Markers MM 1455 and MM 1456 within this region were used for further mapping of this QTL. Finally, qTGW3-1 was fine-mapped into a 89-kb interval between RM5477 and MM1456, which locates in the BAC clone AC107226 harboring five putative candidate genes.

Studies on Plant Population and Stand Establishment Techniques for Increasing Productivity of Rice in Dera Ismail Khan, Pakistan

Rice production in Pakistan is constraint by many factors pertaining to prevalent planting techniques. A research on the feasibility of new planting techniques （direct seeding on flat, transplanting on flat, direct seeding on ridges, transplanting on ridges and parachute planting） in transplanted and direct wet-seeded rice was undertaken at Dera Ismail Khan region of Pakistan＇s North West Frontier Province during 2002 and 2003. Among the planting techniques, the best performance for the yield formation and economic evaluation was noted for transplanting on flat during both years. Chinese parachute planting technology also showed very promising results in most of the parameters. Direct seeding on ridges could not excel transplanting on flat and parachute planting during both cropping seasons. The findings concluded the feasibility of parachute planting technology along with traditional rice transplanting on flat over all other planting techniques being practiced in the area.

Uncertainty in a Measurement of Density Dependence on Population Fluctuations

This article discusses the question of how elasticity of the system is intertwined with external stochastic disturbances. The speed at which a displaced system returns to its equilibrium is a measure of density dependence in population dynamics. Population dynamics in random environments, linearized around the equilibrium point, can be represented by a Langevin equation, where populations fluctuate under locally stable (not periodic or chaotic) dynamics. I consider a Langevin model in discrete time, driven by time-correlated random forces, and examine uncertainty in locating the population equilibrium. There exists a time scale such that for times shorter than this scale the dynamics can be approximately described by a random walk;it is difficult to know whether the system is heading toward the equilibrium point. Density dependence is a concept that emerges from a proper coarse-graining procedure applied for time-series analysis of population data. The analysis is illustrated using time-series data from fisheries in the North Atlantic, where fish populations are buffeted by stochastic harvesting in a random environment.

QTL Mapping of Grain Weight Trait in Rice

To provide new experimental materials for QTL analysis of rice yield trait, we constructed a mapping population of 150 1ines （recombination inbred lines, R1L） derived from a cross between rice varieties V20B and CPSLO17, and localized QTLs and evaluated the genetic effects in the two parents and 150 RILs for thousand-grain weight trait by using internal mapping method of software MapQTL5 combining thousand-grain weight phenotypic data of the RILs. The results showed that a new QTL （qTGW-3） related to thousand-grain weight trait was detected. Individual QTL （LOD=4.14） explained 11.9% of the observed phenotypic variance. And the QTL alleles came from the parent V20B.

武隆区耕地—粮食变化特征及其压力分析

为了指导区域耕地资源的合理利用,运用耕地压力指数、粮食生产波动指数和土地资源承载力指数等指标,对武隆区耕地—粮食资源变化特征及其压力进行了系统分析。结果表明:1999—2021年,武隆区耕地资源减少了约17.8%,但粮食总产量增加了12.5%;武隆区与重庆地区的耕地生产力水平差距由1999—2007年的2.47倍缩小至2008—2021年的1.52倍,耕地压力指数K400基本上在0.93以上,处于耕地压力临界状态;土地资源承载力指数均值为0.954,82.61%的年份处于人粮平衡状态。鉴于此,应该结合武隆区耕地结构以坡地为主的特征,通过加大高标准农田建设、整体提升农田水利设施等措施,缓解耕地—粮食资源压力,促进区域的可持续和高质量发展。

农村人口老龄化对农业高质量发展的影响

基于2004—2020年中国内地30个省市面板数据,在运用熵值法测算出我国农业高质量发展水平的基础上,通过动态面板和门槛效应模型对农村人口老龄化促进农业高质量发展的效果和机制进行了实证检验。研究结果表明:农村人口老龄化能够显著提高农业高质量发展水平,其促进效应在粮食主产区内要强于产销平衡区内,而在主销区内,这一促进效应则并不显著。对农业高质量发展分维度异质性分析后发现:农村人口老龄化通过改善农业高质量发展中农业发展水平、资源条件、经济条件以及技术条件,促进农业高质量发展水平的提高;通过抑制环境条件的改善,阻碍农业高质量发展水平的提高。最后,门槛效应检验结果表明:农村人口老龄化对农业高质量发展的促进效应会随着农业高质量发展水平的提高而得到进一步的增强。