银杏实生树不同发育阶段个体内源激素含量的变化   总被引：3，自引：0，他引：3  

王白坡  程晓建  戴文圣 《果树学报》2002,19(6):395-398

以不同年龄银杏实生树为试材,研究芽尖和叶片中内源激素赤霉素(GA3)、玉米素(ZT)、吲哚乙酸(IAA)和脱落酸(ABA)含量与个体发育阶段的关系。结果表明,7龄期和13龄期银杏实生树芽尖和叶片中上述4种内源激素含量无明显差别,同时与13龄期首次开花的雄株接近,但却和3龄期有显著差异。可见实生树在7龄期前后树高2.5～3.0m已处转变期;随后树体继续生长增高到12～13m,在13龄期前后首次出现雄花和雌花开始进入成年期。芽尖中上述4种内源激素水平不是转变期进入成年期的惟一控制因子。转变期长可能是实生树迟果的原因之一。  相似文献   

根结线虫的研究现状   总被引：50，自引：0，他引：50  

赵鸿  彭德良  朱建兰 《植物保护》2003,29(6):6-9

概述了根结线虫的发生分布和传统分类鉴定,以及分子生物学技术(同工酶电泳技术、DNA重组技术、PCR技术)在根结线虫种和生理小种鉴定中的运用及其防治,并对生物防治及抗根结线虫育种、转基因工程在植物线虫学研究领域上的应用前景作了展望。  相似文献   

小麦苗枯病菌的ITS分析及PCR检测   总被引：8，自引：0，他引：8  

葛芸英  郭坚华 《植物病理学报》2003,33(3):198-202

 小麦苗枯病菌(Clavibacter fangii,Cf)是引起小麦细菌性苗枯病的病原,本研究用16S~23S rDNA间的内源转录间隔区(internally transcribed spacer,ITS)序列通用引物L1(5'-AGTCGTAACAAGGTAGCCGT-3')和L2(5'-GTGCCAAGGCATCCACC-3')扩增Cf和其它相关细菌的基因组DNA;并对其PCR产物进行回收、克隆和测序,将所获序列和其它已报道的细菌ITS序列进行多重比较后设计出Cf的特异性引物I1(5'-TGCCAAGTCACACTGAGACGA-3')和I2(5'-CAATGATCTACCACCCTCCGA-3')。此引物可以从Cf中扩增出351bp的特异性片段,而其余参试的21个细菌PCR反应结果均为阴性。该方法可以应用于小麦苗枯病菌的快速、可靠检测。此外,本研究对多种植物病原棒形杆菌的ITS序列进行比较研究,发现其具有一定的分类意义。  相似文献   

Phylogenetic relationships between rice dwarf phytoreovirus isolates from five countries     

B.C. Lee  Y.K. He  K. Murao  M. Isogai  G. Dahal  I. Uyeda 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(6):493-499

Rice dwarf virus isolates were collected from several locations in Japan, the Philippines, China, Nepal and Korea. Genomic dsRNA segment profiles in polyacrylamide gel electrophoresis differed among the isolates. There were less differences in the profiles between isolates from Japan and Korea than in those between these two Countries and others. Nucleic acid hybridization was used to examine the extent of genomic variation. Full-length cDNAs to all genomic segments encoding non-structural proteins (S4, S6, S9, S10, S11 and S12) were synthesized from two Japanese isolates, and were used for dot-blot hybridization. Hybridizations using probes generated from the full-length cDNA clones failed to differentiate isolates from different geographical areas. However, cDNA probes covering a variable region of S12 were able to distinguish Japanese and Korean isolates from those of other countries. Phylogenetic tree analysis based on the amino acid sequence of P12 encoded by S12 grouped Japanese and Korean isolates together. The Chinese isolates from two different locations (Yunnan and Fujian) were closely related to each other, and were the most distantly related to Japanese and Korean isolates.  相似文献   

盐池半荒漠风沙区土地沙漠化发生发展规律的研究   总被引：1，自引：0，他引：1  

孙德祥  王北 《干旱区资源与环境》1997,11(3):47-52

本文耐盐池半荒漠风沙区土地沙漠化发生发展规律进行了探讨，主要分析了在土地沙漠化的过程中土壤和植被的变化过程及其成因。  相似文献   

干旱指数及其在青海东部旱区特征分析上的应用   总被引：5，自引：0，他引：5  

缪祥辉 《干旱地区农业研究》2004,22(2):136-141,153

在土壤水分平衡关系分析的基础上,提出了分析和评估旱害的5项指标:贫水指数、凋萎指数、降水指数、综合指数和干旱指数,并依据干旱指数对乐都浅山地区1961～1999年的粮食生产进行了年型分类。结果为:39a间共发生特大旱1a,大旱年3a,中旱年19a,轻旱年11a,平水年5a;发生机率分别为2.6%、7.69%、48.72%、26.21%、12.82%。同时认为青海东部地区旱区作物需水和耗水参数矛盾突出,干旱几乎年年发生,具有明显的难以预测性、多变性和不可控性。  相似文献   

The re-emergence of indigenous forest in an urban environment, Christchurch, New Zealand   总被引：4，自引：0，他引：4  

Glenn H. Stewart  Maria E. Ignatieva  Colin D. Meurk  Richard D. Earl 《Urban Forestry & Urban Greening》2004,2(3):149-158

Christchurch, the second largest city in New Zealand is a planned city on a coastal plain on the east coast of the South Island. The birth of the city and the subsequent century of development was characterised by colonial values and tree and garden planting with familiar European species along with those from Australia, North America, and eventually all other continents. The image of an “English garden city” with classical parks of oaks and willow-lined rivers became the accepted norm and the way in which the city has been promoted to potential tourists. Gardening is one of the top two recreational activities and exotic species greatly outnumber native species in the flora and in gardens. This has had serious consequences for the highly fragmented and degraded indigenous vegetation and its co-adapted wildlife. A few hardy indigenous species continued to regenerate through this period, but since the 1970s, there has been a progressive change of attitude and interest in reclaiming the natural heritage of the city, manifest in widespread private and public planting of indigenous species and active habitat restoration. In this article we examine the indigenous and exotic shrub and tree components of the Christchurch flora as planted street trees, in domestic gardens, and in parks. We also present data on shrub and tree regeneration in parks and domestic gardens in the city. Indications are that the more sensitive, less intrusive management of urban environments, combined with the greater density of indigenous seed sources, has allowed regeneration of a wide range of indigenous species across a broad spectrum of habitats – from neglected gardens to pavement cracks to exotic plantations. This is despite the competition from the prodigious seed banks and density of exotic trees, shrubs, and ground covers and albeit minimal impacts of introduced browsing and seed eating mammals. If the present trends continue through appropriate management and facilitation, these tentative signs of native forest regeneration should eventually proliferate into a sustainable mixed origin urban forest that resurrects and preserves the natural character of the region.  相似文献   

Hazard tree liability in the United States: Uncertain risks for owners and professionals     

Michael J. Mortimer  Brian Kane 《Urban Forestry & Urban Greening》2004,2(3):159-165

The liability United States (U.S.) tree owners face from hazardous trees on their private properties has and continues to undergo a transformation. The traditional common law legal test focused upon whether a tree owner had acted to create a hazardous condition on the property. The modern trend is towards a test that imposes greater responsibility and greater uncertainty on tree owners and arborists. Abandoning the natural/artificial distinction, the modern test, adopted in half the U.S. jurisdictions, imposes general principles of negligence on tree owners. This paper discusses the U.S. legal context for hazardous trees, particularly the impacts on individual tree owners. It closes by addressing various practical means to minimize the risks associated with the modern legal standards, both for susceptible tree owners, and for professionals assessing the subject property.  相似文献   

Landscape metrics with ecotones: pattern under uncertainty   总被引：1，自引：0，他引：1  

C. Arnot  P.F. Fisher  R. Wadsworth  J. Wellens 《Landscape Ecology》2004,19(2):181-195

  相似文献   

应用遥感技术对内蒙古镶黄旗草原分类的研究   总被引：1，自引：1，他引：1  

单丽燕  刘荣堂  余鸣  贠旭疆  李新一 《草原与草坪》2005,(1):38-42

研究了遥感技术在内蒙古镶黄旗草原资源调查中的应用,探讨了利用TM影像进行草原资源专题信息提取的整个过程,包括几何校正、镶嵌、特征提取和训练区的选择,采用常规的监督分类和非监督分类方法,对图像进行了分类,同时对分类结果进行了校验。  相似文献