湿球温度资料在农业上的应用

[编者:本文提出用湿球温度作农业气候指标并揭示了一些重要现象,但其实质和应用范围还请广大读者研究讨论]在农业气候资源调查工作中,农业气候区划首先要涉及到合理的农业气候指标问题,而区划指标的合理,它又关系到农业气候区划成果的质量和应用。可是气候中各个气象要素随时间、空间变化相当复杂,因此要确定一个农业气候指标,要求具有时间、空间的使用价值,是十分困难的事情。由于如此,现在我们得出的许多农业气候指标其应用效果大部被严重地局限在某一局部区域之内。山区立体气侯差异很大,亦常因指标的问题严重影响了农业气候区划的质量和成果的应用.为此,本文提出用湿球温度作农业气候指标的方法,并推测湿球温度资料在植物、动物的地理研究等方面具有重要的经济效益.     

精细化农业气候区划业务流程初步设计

根据以往农业气候区划的实践,结合现代农业气象业务需求及精细化农业气候区划的特点,初步设计了精细化农业气候区划业务流程。业务流程主要包括确定区划对象、区划对象与气候条件的关系分析、资料的收集与处理、区划指标及区划方法的确定、区划图的制作、区划结果的检验、报告的撰写以及区划产品的服务过程。农业气候区划业务流程的制定对规范和指导精细化农业气候区划业务工作具有重要现实意义。     

GIS在广西龙眼种植优化布局中的应用

广西具有发展龙眼的适宜气候条件，却由于品种结构和区域布局不合理而没有取得理想的经济效益。为了优化广西龙眼区域布局和品种结构，根据龙眼的生物学特性及产量与气候要素的相关分析，筛选出龙眼生长发育的限制性气候要素，确定了龙眼种植的气候区划指标。利用广西89个站点的气候资料和1∶25万地形数据，建立了区划指标的空间分析模型。在GIS平台上按1 km×1 km细网格对区划指标进行了小网格推算，并利用反距离权重插值法对其残差部分进行空间内插；将推算结果和插值结果进行迭加，实现对区划指标小网格栅格数据的订正，使推算的结果更为精确。采用GIS技术对龙眼种植区进行气候区划，该区划按种植龙眼的气候适宜性，将广西划分为最适宜、适宜、次适宜和不适宜气候区，绘制了龙眼优化布局的细网格区划专题图。在此基础上，进一步对龙眼品种的优化布局问题进行研究探讨，给出了比较合理的早、中、晚熟品种的适宜种植范围，并分区进行评价和提出相应的建议。研究结果为广西龙眼生产提供了科学的依据。     

基于GIS的广东香蕉种植气候适宜性区划

以广东省86个气象站点1992-2005年的气象数据为依据、利用数理统计方法对1992-2005年香蕉平均气象产量与同期气候条件进行相关分析,确定香蕉种植的气候适宜性区划指标。根据广东86个站点1970-2009年的气候资料及对应站点的经纬度、海拔高度、坡度和坡向等基础信息数据,应用多元线性回归确定区划指标空间分析模型,推算出1km×1km的气象要素分布图。依托GIS技术空间分析功能,根据综合评分标准进行香蕉种植气候适宜性区划,得出广东省气候上最适宜种植香蕉的土地面积占17%,适宜区占18%,次适宜区占25%,不适宜区占40%。研究结果可为广东香蕉种植的合理布局提供参考。     

地理信息系统在县级农业气候区划中的应用

利用City Star(3.0)地理信息系统软件和广西1：25万基础地理数据，开展了容县沙田柚种植的农业气候区划，取得了较好的效果。提出了应用GIS技术开展县级农业气候区划的新思路、新方法和具体步骤。     

农业气候区划方法研究进展

农业气候区划是合理利用农业气候资源的有效途径,得到了广泛地关注和应用。本文着重从农业气候区划指标选取方法、农业气候区划方法以及地理信息系统在农业气候区划中的应用三个方面,总结了农业气候区划方法的研究进展,评述了不同区划方法的优缺点,并提出了未来可能的研究方向,以期对该领域的研究提供参考。     

GIS支持下的三峡库区湖北段农业气候资源评估与区划

根据三峡库区湖北段现有气象站网和亚热带东部山区气候考察资料 ,建立其相应的光、热、水资源小网格推算模式。引入CityStar中的经纬线、数字高程等图层 ,推算了该地区 10 0m× 10 0m网格点上的农业气候资源要素值 ,再利用区划制作系统 ,按照给定的农业气候资源分区指标 ,得到该区农业气候资源区划专题图 ,为三峡库区湖北段的农业合理布局提供了农业气候依据     

基于GIS的陕南柑桔气候生态适宜性区划

陕南秦巴山区地处北亚热带气候区,是柑桔种植北缘地带。为了科学、合理地利用当地农业气候资源,进一步优化产业结构,达到趋利避害、防灾减灾的目的,本文根据陕南秦巴山区近30a的气候资料,采用极端最低气温多年平均值、1月平均气温、年平均气温及年降水量4个因子作为陕南柑桔气候适宜性区划指标;利用GIS空间分析及制图功能,在实现区划指标空间化基础上,采用模糊综合评判方法,对陕南秦巴山区柑桔气候适宜性进行区划,并对各适宜区柑桔生长气候条件优劣进行评述。结果表明,陕南柑桔气候适宜区主要分布于秦巴山区海拔700m以下的浅山丘陵区,在适宜区内,应根据地形特征,选择冷空气不易堆积的＂难进易出型＂丘陵坡地栽培,以减少冻害。     

GIS技术在常山县胡柚种植气候区划中的应用

根据胡柚生长发育与气象条件的关系，确定了胡柚种植的农业气候区划指标。运用浙江省1∶25万地形数据和常山县气象站40年的气候资料，建立区划指标的高层模型，应用GIS技术对常山县胡柚适宜种植区进行气候区划，该区按种植胡柚的适宜性划为最适宜种植区、适宜种植区、次适宜种植区和不适宜种植区，为常山胡柚的推广和发展提供参考。     

我国甘蔗的气候生产力特征分析

根据广西柳州９县１９５２～１９９０年甘蔗逐年产量和７县２５年含糖量资料，在采用方差分析和滑动相关分析确定影响甘蔗产量和品质的关系发育期及气候影响因素的基础上，建立气候影响方程，并提出气候产量和气候含糖量的影响指数（Ｃｙ与Ｃｓ）。结合甘蔗产区３８站１７年气象整编资料，对我国蔗区作出气候生产力分析和区划，为今后扩大甘蔗种植面积提高单产和品质提供切实有效的分析数据。     

“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.     

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     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.     

Short-term variation in the concentration of selected ions within individual tropical rainstorms

Rainwater was collected at the campus of the University of Brunei Darussalam in Bandar Seri Begawan, Brunei Darussalam, using a funnel-in-bottle sampler. Polypropylene bottles were changed at intervals during rainstorm events. The pH and conductivity were determined immediately after collection on aliquots of the sample. Samples were refrigerated at 5°C for subsequent chemical analysis. Analyses for Na, Mg, Ca, Zn and Fe were carried out by means of inductively coupled plasma atomic emission spectroscopy (ICP-AES); Cu and Mn were analysed by graphite furnace atomic absorption spectroscopy (GFAAS); K was analysed using flame atomic emission spectroscopy (FAES); and Cl^–, NO₃ ^– and SO₄ ^2– were analysed by ion chromatography (IC). Concentration versus time profiles are reported for three rainstorm events. All ions exhibited a decrease in concentration during the rainstorm. The first sample contained the highest concentration of ions, consistent with a first-flush effect. The contribution of the initial stages of the shower to the total quantity of ion deposited during the entire rainstorm is quite overwhelming; in many cases 20 to 30% of the mass was deposited in less than 5% of rainstorm duration. On the other hand, the pH and conductivity variation during rainstorms did not exhibit a consistent pattern.     

The 5S rRNA gene diversity in the genus <Emphasis Type="Italic">Secale</Emphasis> and determination of its closest haplomes

We analyzed 127 rDNA sequences (5S DNA units) obtained from 23 seed accession samples from more or less 10 taxa in wild and cultivated rye, genus Secale L. The sequences fell into two known groups, here assigned to two unit classes, viz. long R1 and short R1 (designations to reflect on R haplome of rye). The different taxa could not be fully differentiated based on the 5S DNA units. We searched for 5S DNA sequences from known unit classes most closely similar to the long R1 and the short R1. One set with the long R1 unit class contained sequences of the long P1 unit class from Agropyron (P haplome) and from Kengyilia (StYP haplome), long J1 from Thinopyrum (J haplome), whereas the set with the short R1 included the long S1 from Pseudoroegneria (St haplome) and Kengyilia (StYP haplome), the short J1 from Thinopyrum (J haplome) and the short V1 from Dasypyrum (V haplome). Each of the two sets was analyzed separately by maximum likelihood (ML) phylogenetic analysis from which we were able to infer that the 5S DNA units of Secale differentiated in a non-clock fashion and followed the HKY substitution model in the gene tree with the long R1 unit class and the HKY + G in the gene tree with the short R1 unit class. A complementary Bayesian analysis yielded identical tree topologies to the ML ones for each of the two sequence sets. In the tree with the long R1 units the long P1 and long J1 unit classes were closest to the long R1 unit class, whereas in the tree with the short R1 units the long S1 and short J1 unit classes were closest to the short R1 unit class, indicating possibly a close relationship between the St, J and R haplomes.     

Leaf litter selection by detritivore and geophagous earthworms

Summary Litterbag experiments with 10 different kinds of leaf litter showed that detritivore (Lumbricus species) and geophagous (Aporrectodea species) earthworms prefer certain litter types over others, since different numbers of worms were found below the litter after 50–52 days of exposure in a pasture. The detritivores preferred Fraxinus, Tilia, and predecomposed Ulmus and Fagus litter to Fagus litter and paper, while geophages preferred Tilia litter to Alnus and Ulmus litter, so that the two groups of earthworms showed different preferences. The detritivores seemed to be more selective than the geophages. The palatability of the litter was examined in relation to the C: N ratio, the lignin concentration and the initial and final polyphenol concentration. The numbers of detritivores were significantly correlated with the C: N ratio and the final polyphenol concentration, so that selection of litter seems to be related to palatability. The numbers of geophages were not significantly correlated with any of the parameters for palatability. The disappearance of litter after 50–52 days appeared to be due to detritivore activity, since the numbers found below the litter were positively and significantly correlated with the litter disappearance. There was no significant correlation with geophage activity. This indicates that detritivores use litter as food, and therefore influence the composition of the litter layer.     

Nematode succession and microfauna-microorganism interactions during root residue decomposition

The quality of plant material affects the vigor of the decomposition process and composition of the decomposer biota. Root residues from hairy vetch (Vicia villosa Roth), rye (Secale cereale L.) and vetch+rye, packed in litterbags were placed in pots of soil at 15 C and the content of the bags was analyzed after 2, 4, 8 and 12 weeks. Bacterial biomass did not differ between residues with contrasting composition. Among bacterivores groups of nematodes that require high bacterial production dominated in fast decomposing resources whereas flagellates with smaller requirements prevail in slower decomposing resources. Biomass of bacterial feeding nematodes correlated positively with early phase (0-2 wk) decomposition that increased in the order: rye< vetch+rye<vetch. Bacterial biomass therefore seems to be under top-down (predation) control during early decomposition. In contrast, the fungal biomass differed between resources with highest values for rye. Moreover, this increase in fungal biomass occurred later during succession and was correlated with decomposition activity for rye in that period. Fungal biomass therefore seems to be under bottom-up (resource) control. The composition of the nematode assemblages (composed of 25 taxa) showed a clear relationship to initial plant resource quality as well as decomposition phase. Early successional microbivorous nematodes vary according to resource quality with demanding bacterivores+predators (Neodiplogasteridae) dominating in vetch and less demanding bacterivores (Rhabditidae) and fungivores (Aphelenchus) being equally common in vetch and rye. Later in the succession (2-4 wk) bacterivorous Cephalobidae and fungivorous Aphelenchoides prevailed similarly on the different root materials whereas bacterivorous protozoa and the amoebal fraction thereof dominated in rye. At week 12 no species dominated the nematode assemblages that were similar between the resources. The differences between nematode assemblages among plant resources at 2 week were similar to the results of a field study sampled after 6 weeks with the same soil and plant resources. This lends support to the relevance of the successional patterns observed in this incubation study.     

Cycling of extracellular DNA in the soil environment

Upon entering the soil environment, extracellular DNA is subjected to dynamic biological, physical, and chemical factors that determine its fate. This review concerns the fate of both recombinant and non-recombinant sources of DNA. A schematic of DNA cycling coupled with genetic transformation is presented to understand its behavior in soil. Extracellular DNA may persist through cation bridging onto soil minerals and humic substances, be enzymatically degraded and restricted by DNases of microbial origin, and/or enter the microbial DNA cycle through natural transformation of competent bacteria. Lateral gene transfer may disseminate DNA through the microbial community. An understanding of DNA cycling is fundamental to elucidating the fate of extracellular DNA in the soil environment.