陕西省粮食安全时空变化及预测研究

本文利用耕地压力指数模型定量测评陕西省及各县1949-2006年的粮食安全程度, 结合耕地压力动态度进一步分析区域的粮食安全变化速度, 在历史研究的基础上, 利用灰色系统模型对未来陕西省粮食安全走势做出预测。分析结果表明：1949-2006年, 陕西省的耕地压力指数呈下降趋势, 以人均粮食占有量400 kg的消费水平标准, 耕地压力指数从1949年的1.591降至2006年的1.298, 粮食安全问题趋于缓和;各县的耕地压力指数存在明显差异, 关中平原大部分地区偏小, 陕北黄土高原的榆林、延安地区和陕南秦巴山地的商洛地区偏大;各县的耕地压力指数变化率存在明显差异。陕西省粮食安全问题目前依然存在, 未来区域粮食安全问题应高度关注。     

陕西省耕地生产能力的时空分布

为了明确陕西省耕地生产能力的现状,该文利用2008-2010年陕西省各县平均粮食产量数据,结合GIS分析描述陕西省各县耕地实际利用强度、理论利用强度、耕地可实现增产潜力和理论增产潜力及其空间分布变化规律;利用1978-2008年陕西省粮食产量和消费数据计算耕地压力指数的时序变化规律。结果表明:耕地实际利用强度较小地区集中在陕北中部、关中西部,这些地区提高利用强度空间较大,是生产技术投入和劳动力投入的主要区域;耕地理论利用强度呈现出中西部地区高,北部和东南部地区低的分布规律;耕地压力指数时序表明陕西省自1978年以来,耕地压力年级间波动较大,近几年由于科技进步和政策导向致使耕地压力减小,耕地保护与耕地占用之间矛盾缓和;可实现增产潜力较大区域分布于陕北中部和关中西部,而陕南大部分地区可实现增产潜力较小,陕北北部和关中北部可实现生产潜力居中;耕地理论增产潜力呈东南部高,西北部低的空间分布规律,该文为陕西省耕地利用规划、土地整理和粮食安全提供科学依据。     

渭南市耕地变化对粮食安全的影响评价

利于最小人均耕地面积和耕地压力指数模型,对渭南市1990-2006年由于耕地面积变化所引发的粮食安全状况进行评价.结果表明:渭南市耕地面积变化经历了逐年减少、波动变化和趋于稳定3个阶段,耕地面积变化的区域差异不明显,人均耕地面积变化呈现明显减少的特点;正常年份渭南市粮食供给处于安全水平,在粮食生产遭遇自然灾害时,粮食安全状况就会受到影响;粮食安全表现出明显的区域差异性,未来8 a内渭南市的粮食安全不会受到威胁.研究结果将为合理解决渭南市耕地利用与粮食安全之间的矛盾提供科学依据.     

湖北省耕地压力的区域差异及动态演进分析

为充分认识湖北省耕地压力区域差异、动态演进规律,以保障湖北省的粮食安全,该文用修正耕地压力指数测度湖北省及其17个城市耕地压力大小,从时序和空间两方面分析湖北省区域内耕地压力变动差异,并利用核密度估计方法分析湖北省区域内耕地压力演变规律。结果表明:1)2000-2016年,湖北省平均耕地压力为警报压力,区域内人均所需最小耕地面积与实际人均供给面积差距较小,能够实现湖北省区域内粮食安全有效供给。2)2000-2016年,湖北省区域内耕地压力变化不一,其中鄂东区域耕地压力最大,鄂中区域耕地压力最低。3)耕地压力的总体水平在2000-2016年间逐渐减小,但是地区差距也不断加剧,极化现象十分明显。4)分区域看,鄂东地区的耕地压力总体水平不断减小,地区差距较大,两极化现象较突出;鄂中耕地压力水平低,地区差距不大,两极分化不明显;鄂西耕地压力水平居中,存在地区差距,两极分化没有鄂东地区明显。     

江西省耕地压力时空差异分析及预测

根据最小人均耕地和耕地压力指数模型,结合GIS软件,分析了1981年以来江西省耕地压力时空变化规律,并运用平滑预测理论,对2007-2015年人均耕地面积、最小人均耕地面积以及耕地压力指数进行了预测.结果显示:1981-2006年江西省耕地压力指数呈波动式上升趋势,耕地压力地区差异明显:未来9年内,人均耕地面积继续减少,耕地压力指数随之进一步增加,到2015年人均耕地面积将减少到0.0306 hm2/人,耕地压力指数随之达到1.61,耕地压力更加明显,粮食安全受到威胁.限制非农占用耕地、优化用地结构、增加复种指数、提高耕地效益,是降低耕地压力、减缓人地矛盾的有效对策.     

安徽省沿江地区耕地利用集约度及粮食安全相关分析

利用1989—2008年的耕地资源与粮食统计数据,运用主成分分析和回归模型预测的研究方法,分析了近20 a安徽省沿江地区耕地利用集约度、粮食安全水平以及二者的相关性。结果表明：（1）耕地利用集约度时序变化明显,为＂两升两降＂4个变化阶段,其空间差异显著,以北高南低为主要特征;（2）粮食安全指数大体处于安全状态,指数波动起伏上升,区域发展不均衡;（3）耕地利用集约度与粮食安全指数二者相关性系数较大,相关性明显。该研究结果可为安徽省沿江地区耕地资源合理利用和保障粮食安全提供理论依据。     

黑龙江省宝泉岭垦区粮食生产动态分析与预测

保持一定数量的耕地资源是实现区域粮食安全的重要保障.以黑龙江省宝泉岭垦区为研究区,从耕地压力角度出发,采用耕地压力指数模型,基于商品粮基地具有向国家提供商品粮的特殊地位,综合考虑国家粮食安全和区域粮食安全的关系,对1989-2008年宝泉岭垦区耕地与粮食生产状况进行了分析,运用时间序列、灰色系统模型及DPS数据处理系统软件,对2011-2020年宝泉岭垦区的粮食安全状况进行了预测.结果表明:20 a来宝泉岭垦区粮食一直处于安全状态,宝泉岭垦区粮食安全动态变化情况大致分为三个不同阶段:1989-2000年耕地压力指数波动上升,2001-2003年耕地压力指数下降,2004-2008年耕地压力指数波动上升.在未来10 a,在满足商品率为91%的条件下,年末总人口、耕地面积、粮食总产量逐年增加,耕地压力指数持续降低,在满足区域粮食安全的基础上,粮食商品率有很大的提升空间.最后,提出继续加强政策支持力度、依靠科技进步、严格保护耕地等建议以进一步提高宝泉岭垦区的粮食生产能力.     

陕西省耕地资源变化及耕地压力指数分析与预测

为了阐述陕西省的耕地面积变化及其压力状况,基于60 a统计数据,分析了陕西省耕地数量随时间变化特点,计算了耕地压力指数,利用GM（1,1）模型预测了全省未来10 a耕地面积及其人均耕地面积变化。结果表明,1949－2010年的60 a时间里,陕西省耕地面积总体呈现下降趋势,下降了152.41万hm2,旱地是耕地的主体,减少了181.35万hm2,而水浇地面积增加了77.51万hm2,耕地结构趋于合理;人均耕地面积下降了0.28 hm2, 1980年以前的30 a时间下降最明显,到2010年为0.10 hm2。未来10 a里,全省耕地面积和人均耕地面积会有一定的下降,但降幅不明显,且3种预案条件下（人均年粮食需求量380、400、420 kg）,耕地压力过大出现的时间不同,人均年粮食需求量420 kg下最小人均耕地面积出现的时间最早（2014年）,人均年粮食需求量400 kg下最小人均耕地面积出现在2017年,并基于此对陕西省粮食安全问题提出了相应建议。     

1978-2015年中国多尺度耕地压力时空差异分析

为充分认识中国耕地压力的现状、变化趋势和空间分布差异,以保障中国的粮食安全,该文利用修正的耕地压力指数模型计算了中国31个省级行政区域1978－2015年的耕地压力指数,并在此基础上从国家、四大经济区域、省域3个尺度分析了耕地压力指数的时序变化和空间分布差异;该文借鉴力学原理,引入耕地压力重心的概念,通过计算耕地压力重心坐标,进一步揭示了耕地压力指数的空间变动情况。研究发现,中国耕地压力指数表现出明显的地域差异性,耕地压力重心随时间推移逐渐向东南方向移动,具体表现为东部地区耕地压力逐渐增加,西部地区耕地压力始终较高,而中部和东北地区耕地压力基本稳定在安全状态;通过对各省耕地压力指数进行系统聚类,可将中国31个省级行政区分为4种类型,分别为高压力型、中压力型、低压力型和无压力型。最后该文基于上述研究结果,对于不同耕地压力程度和类型的地区提出针对性的建议来缓解耕地压力,以更有效地保障各地区的粮食供给。     

退耕还林（草）背景下延安市粮食安全态势评析

延安市的粮食生产与粮食安全问题关系到延安市退耕还林（草）工程的持久、稳定。运用最小人均耕地面积和耕地压力指数模型法,采用耕地面积、粮食产量、人口数量等数据,分析了1997-2007年延安市粮食安全状态。结果表明：在空间上,延安市宝塔区以南县区的耕地压力指数、最小耕地面积较小,粮食生产压力小,耕地的生产力高;在时间上,1998-2003年延安市耕地压力指数、最小耕地面积呈上升态势,2003年后则趋于下降。近些年耕地压力指数略高于1,区内耕地压力、粮食供需矛盾有所缓解,但粮食安全问题依然存在。对此,延安市应控制人口增长,通过改造中低产田、旱作农业技术的应用等途径稳定粮食生产。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.