新疆库尔勒市城市化发展与耕地资源协调性分析

城市化水平是衡量一个国家经济发达程度,特别是工业化水平高低的一个重要标志,而耕地非农化是城市化过程中的一种必然现象,耕地数量变化体现一定的社会经济发展规律。基于库尔勒市1989—2012年的社会、经济统计数据应用一元线性回归模型和协调度分析法分析库尔勒市城市化水平和耕地资源的变动情况、相关性以及协调性,并采用1990年,2000年,2010年3期Landsat TM,ETM+,ALOS/AVNIR-2数据作为数据源,提取城市和耕地面积信息,结果表明:近24 a库尔勒市的城市化水平有所提高,年均城市化水平增长率达到0.2%,年均耕地面积增长率达到4%,人均耕地面积增长率是1.5%。库尔勒市近年耕地资源与城市化水平呈现出相互促进的正相关关系;从协调度时序上看,库尔勒市城市化水平与耕地资源的协调度总体呈现出“基本协调和较协调→不协调→调和和较调和”的趋势。     

成渝城市群城市土地-耕地利用效率时空耦合研究

[目的]评价成渝城市群城市土地利用效率及耕地利用效率,促进成渝城市群新型城镇化与农业现代化的共同发展。[方法]基于2005—2014年统计数据,建立城市土地利用效率与耕地利用效率的指标体系,综合运用Super SBM模型、重心转移模型及耦合协调度模型,分析成渝城市群城市土地利用效率、耕地利用效率的时空格局及二者的耦合协调水平。[结果](1)2005—2014年,成渝城市群城市土地利用效率呈波动向上发展,效率重心垂直向南移动幅度较大;(2)耕地利用效率整体上呈现V形波动,效率重心在水平方向上向东转移趋势明显;(3)研究区域内城市—耕地利用效率耦合协调类型数量呈"纺锤状"结构分布,高耦合中协调度型城市数量众多,南—泸一线城市耦合协调类型变化强烈。[结论]成渝城市群城市土地—耕地利用效率耦合协调度较高,呈良性发展态势。     

河南省耕地资源与城市化发展的协调性分析

耕地资源与城市化水平之间存在着密切的关系.以河南省所辖地区为研究单元,分别构建了耕地资源指数和城市化水平指数,采用主成分分析法对1990,1995,2000和2005年河南省各地区的耕地资源和城市化水平进行了数量化.然后利用协调度模型对4个年份各个地区的耕地资源与城市化水平协调度进行了定量分析,并划分出协调发展类型.结果表明,各年份耕地资源指数的区域分布特征基本一致,河南省城市化水平呈现出明显的上升现象.协调度的高低由两种指数的大小及其之间的差异决定,河南省耕地资源与城市化水平之间的协调度逐步上升.在研究前期,耕地资源与城市化水平失调的地区主要是传统的农业区;而在研究后期,两者失调的地区主要集中在工业基础较好、城市化水平较高的地区.     

城市化对都市农业景观的影响*--以西安市长安区为例

城市化对都市农业景观的影响日益显著,研究城市化对都市农业景观格局的影响对协调城市化与都市农业发展、优化城市与都市农业功能、把都市农业景观融入城市景观建设具有重要意义。本文以西安市长安区为案例,利用遥感、GIS及FRAG-STATS 3.3软件对研究区都市农业景观(耕地和园地)变化进行了分析,并利用SPSS软件分析了城市化与都市农业景观格局的关系。结果表明:①随着城市化的发展,长安区耕地面积减少,2011年耕地聚集度比1999年下降了2.45%;而园地面积增加,斑块形状趋于复杂,2011年聚集度比1999年上升了10.44%。②研究区内15个乡镇(街道)的耕地破碎度呈上升趋势,而园地面积在各乡镇(街道)都表现为增加,聚集度上升。③相关关系表明,随着城市化水平提高,耕地面积减少,破碎度上升,但综合城市化与耕地斑块数量、形状指数、聚集度等的相关性尚难以确定;而园地随城市化水平的提高,在空间上呈集聚趋势;除此之外,城市化与园地的景观指数相关系数普遍较低,相关系数都小于0.5,相关性不显著。④不同城市化水平对耕地和园地的作用机制不同,耕地在较高城市化水平和较低城市化水平下与城市化景观指数的相关关系相对明确;但园地在中、低城市化水平下城市化与其对景观的影响作用机制比较复杂,相关关系不明确。因此得出,园地在城市中面积增加但分布零散,在以后的城市规划工作中应重视这一部分。     

河南省城市土地集约利用与城市化耦合协调性评价

土地集约利用与城市化耦合协调性程度共同影响着城市系统的发展状态,准确把握二者之间的耦合协调性时空特征,对制定城市土地利用政策和城市化发展战略具有重要的参考价值。在城市土地集约利用和城市化内涵解析的基础上,建立了评价指标体系,以河南省地级市为例,采用2006年、2009年、2012年指标数据,运用熵值法和耦合协调模型,对城市土地集约利用与城市化耦合协调性进行了评价。结果表明:(1)城市土地集约利用出现波动,但城市化综合指数稳步上升,二者之间的相对发展关系总体上由超前型向同步型发展;(2)城市耦合协调度和发展度均呈上升趋势,但空间分布特征差异明显;(3)城市耦合协调发展阶段总体上由拮抗期经磨合期向协调期发展。最后,采用2012年数据,依据城市耦合协调类型划分标准,将河南省划分为4种耦合协调类型,即磨合期V、磨合期Ⅵ、协调期Ⅷ和协调期IX。     

长沙市耕地时空动态变化及驱动力研究

基于1990-2006年期间耕地和社会经济发展历史数据,分析长沙市耕地资源的发展现状和时空变化特点,并运用主成分分析法和多元回归分析法对长沙市耕地非农化的驱动力进行研究.结果表明,(1)长沙市耕地面积在1990-2003年呈逐步下降趋势,年均耕地递减率约为0.26%;2003-2006年耕地呈小幅度增长趋势.(2)区域差异度计算结果表明,长沙市不同的区县耕地变化速度和区域差异明显,耕地变化较为剧烈的地区为社会经济发展较为快速的区县.(3)主成分分析表明,长沙市耕地变化的驱动因子主要可以总结为经济发展水平因子和农业科技水平因子,其中经济发展水平因子是最为关键因素.(4)多元回归分析也表明,经济因素是长沙市耕地变化最为重要影响因素.     

河南省城市化与生态环境耦合协调状态的时空格局

[目的] 探索河南省城市化与生态环境耦合协调状态的空间聚集特征,提出相关的发展建议,为河南省城市可持续发展提供科学的参考。[方法] 通过构建城市化与生态环境评价体系,利用改进的耦合协调度模型,研究2008—2018年河南省城市化与生态环境发展水平及耦合协调度,对河南省17个地级城市耦合协调度进行时空格局分析。[结果] 2008—2018年全省耦合度值都在0.9以上,耦合协调度呈波动上升趋势;多数城市的城市化水平低于生态环境水平,各市城市化与生态环境的耦合协调度等级有基本不协调、基本协调、协调、高级协调;城镇化与生态环境耦合协调存在空间正相关性,有西部和中部耦合协调度高、东南部耦合协调度低的聚类特征。[结论] 河南省整体城镇化进程加快,经济城市化和生态环境压力分别对城市化和生态环境两大系统产生了重要影响。应加强郑州市中心城市的发展,推动河南东南部城市的发展。     

区域耕地变化与人口及经济增长的关系研究——以湖南醴陵市为例

采用1990-2004年的统计资料,分析了近15年醴陵市耕地变化与人口增长、经济发展之间的动态关系,建立了耕地面积变化与人口、人均GDP、固定资产投资总额、城市化水平之间的曲线回归模型。结果表明：1）15年来,醴陵市土地开发强度大,耕地面积和人均耕地面积经历了缓慢减少-快速减少的变化过程,特别是近5年间耕地流失达到一个高峰;2）醴陵市耕地面积减少与人口、人均GDP、固定资产投资总额,以及城市化水平之间具有显著的相关性,经济发展和人口增长对全市耕地面积变化影响仍然很大,全市耕地减少的趋势将在一定时间内继续存在;3）研究结果对当地耕地保护、产业结构调整,实现耕地资源与人口、经济的可持续发展具有一定的参考意义。     

河南省耕地集约利用时空变化特征研究

耕地集约利用水平影响着国家粮食安全及区域的可持续发展,以河南省18个地级市为评价单元,采用最优组合赋权法、协调度评价模型、聚类分析法、GIS空间分析方法定量分析了1989—2008年间河南省耕地集约利用水平的时空变化特征。结果表明:1989—2008年间河南省耕地集约利用水平呈波动上升的趋势,其耕地投入强度和利用效益对耕地集约利用水平影响较大;省域范围内耕地集约利用水平空间差异显著,呈现4级分布,河南北部、东部、南部地区耕地集约利用水平较高,中部次之,西部相对较低;区域间投入强度、利用程度和利用效益差异明显,且出现错位发展。1989—2008年间河南省耕地集约利用水平逐步提高,平原地区的耕地集约利用水平高于山地丘陵地区,且向山地丘陵地区不断扩展,评价结果与现实情况基本一致。     

滁州市近30年来耕地数量与城市化之间协调性研究

在不同的经济发展水平和增长阶段,耕地资源数量呈现不同的变化特征.研究区域耕地资源数量变动与城市化的协调性,对于正确认识和妥善处理经济发展与耕地资源保护之间的关系具有重要借鉴意义.本文基于滁州市1974-2004年近30年的统计数据,应用协调度模型分析方法,计算了滁州市1974-2004年耕地数量变化与城市化的协调度,并对其动态变化进行了分析.结果显示,滁州市耕地协调度与城市化明显呈阶段性分布,说明过去30年间滁州市耕地变动与城市化之间存在不协调因素.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

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     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.