In vitro conservation of tropical plant germplasm — a review     

F. Engelmann 《Euphytica》1991,57(3):227-243

Summary In vitro medium term conservation of tropical plant germplasm is used routinely in many laboratories. Growth reduction is achieved by modifying various parameters, such as temperature, culture medium, gaseous environment. For long term conservation, cryopreservation (i.e. storage in liquid nitrogen, –196°C) is the only current method available. Each successive step of the process requires precise conditions which have to be defined for each material. Cryopreservation protocols have been set up for more than 40 tropical species. Results obtained with various culture systems such as cell suspensions, protoplasts, calluses, meristems and embryos are discussed. The first example of the large scale application of cryopreservation (oil palm somatic embryos) is presented.  相似文献   

Breeding Panicum maximum in Brazil. 1. Genetic resources,modes of reproduction and breeding procedures     

Y. H. Savidan  L. Jank  J. C. G. Costa  C. B. do Valle 《Euphytica》1989,41(1-2):107-112

Summary Apomixis is widely distributed among tropical forage grasses, and has long been merely regarded as an impediment to breeding. Panicum maximum is presented as the first opportunity for Brazilian geneticists to develop and test original breeding schemes adapted to an apomictic species.A large and representative germplasm of P. maximum has been introduced and is currently being evaluated. Basic knowledges on biology and reproduction are also available, which demonstrate an easy manipulation of apomixis and sexuality. Several limiting traits have already been detected during evaluation, which justify breeding attempts. An ideal scheme is given to transfer new qualities to already selected varieties.  相似文献   

Genetic-diversity assessed by microsatellites in tropical maize populations submitted to a high-intensity reciprocal recurrent selection     

Luciana Rossini Pinto  Maria Lucia Carneiro Vieira  Cláudio Lopes de Souza Jr  Anete Pereira de Souza 《Euphytica》2003,134(3):277-286

BR-105 and BR-106 are important tropical maize populations, which were submitted to a high-intensity reciprocal recurrent selection, generating the IG-3 and IG-4synthetics. Using 30-microsatellite loci,we measured and compared the genetic diversity of these populations and their synthetics. The populations did not differ significantly regarding the amount of genetic diversity. As a consequence of selection, genetic variability losses, in terms of mean number of alleles per locus,proportion of polymorphic loci, and gene diversity did occur and were greater in the synthetic IG-3 than IG-4. In the synthetics, the number of loci in adherence to Hardy-Weinberg proportions was superior to that observed in the populations. The Wright's mean fixation index was higher than the mean value expected for outcrossing species (5%) indicating as light excess of homozygotic individuals in both populations. The genetic distances confirmed the favourable effects of one cycle of recurrent selection, as the synthetics became more isolated in comparison to the original populations. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Influencing the global through understanding the local: Harold Brookfield's contribution to international organisations' biodiversity policy     

Juha I. Uitto 《Asia Pacific viewpoint》2005,46(2):143-151

Abstract: This article focuses on a significant paradigm shift in the approaches to biodiversity conservation in the developing countries that has affected important international organisations, including the Global Environment Facility (GEF). This paradigm shift marks a movement beyond protected areas to production landscapes. It is argued that one particular project, People, Land Management and Environmental Change (PLEC), developed under the leadership of Harold Brookfield has contributed significantly to the shift. The project was instrumental in introducing the term ‘agrodiversity’ that encompasses biological diversity as well as the management diversity found in smallholder agricultural systems at all levels. The article describes the evolution of PLEC into a major international collaborative project funded through the GEF. It highlights the project's main achievements and its influence on the policy‐making in the GEF relying on the findings of independent evaluations.  相似文献   

红壤小流域热带水果产量潜力估算与气候适宜性分析 --以敢上小流域为例     

余定诚  广西大学 《广西农业生物科学》2001,20(3):173-176

采用联合国粮农组织推荐的“农业生态地带法”,结合层次递减法 ,对敢上小流域龙眼、荔枝、芒果经济产量潜力进行了估算 ,并依据影响龙眼、荔枝、芒果产量的关键气象因子进行气候适宜性分析。结果表明 :敢上小流域适宜发展芒果和早熟龙眼、荔枝 ,不宜发展迟熟龙眼、荔枝 ,要实现果树稳产、高产必须有效克服水分条件对生产潜力的制约  相似文献   

海南尖峰岭热带山地雨林生理生态功能群特征   总被引：2，自引：0，他引：2  

陶晶  臧润国  李意德  毛培利  林明献 《林业科学》2011,47(8)

在海南尖峰岭热带山地雨林,野外测定获得3个与植物-大气相互作用直接相关的生理生态特性指标(最大净光合速率、最大气孔导度和比叶面积),应用等级聚类分析和NMS排序方法对热带山地雨林的主要植物进行功能群划分,分析热带山地雨林4个演替阶段(初期、早期、中期和后期)生理生态功能群组成及其动态规律。结果表明:海南尖峰岭热带山地雨林的87个主要植物种类可划分为8个功能群,检验结果显示功能群间存在显著差异,而功能群内同质性较高;功能群的丰富度及相对多度在不同演替阶段差异显著;功能群的丰富度在演替初期最低,演替早、中期最高,演替后期略有降低;演替初期的优势功能群光合能力强,水分利用效率低,演替早、中期的优势功能群光合能力、水分利用效率均为中等;演替后期的优势功能群光合能力偏低,水分利用效率高。  相似文献   

Using ecological niche modelling to identify diversity hotspots for the herpetofauna of Pacific lowlands and adjacent interior valleys of Mexico     

Andrés García 《Biological conservation》2006,130(1):25-46

This article documents the conservation status of the herpetofauna in the Pacific lowlands and adjacent Balsas Basin and Chiapas Depression regions and the presents the results of modelling species spatial distributional patterns through GARP analysis, to identify hotspots of species richness, endemic and geographically restricted species in the study area. It also compares the distribution of these hotspots with the distribution of protected areas and intact seasonally tropical dry tropical forests, the dominant vegetation type in the study area and experiencing high deforestation rates. A total of 301 reptiles and amphibian species occur in the study area accounting for a third of the Mexican herpetofauna, and recording high levels of endemism and endangerment. Hotspots of species richness and endemism were located in coastal Jalisco, a considerable portion of the Colima state, as well as scattered areas in Michoacán, Guerrero, and Oaxaca. These areas should receive highest priority for protection. Unfortunately, there was a minimum correspondence when comparing the distribution of actually and proposed protected areas with hotspots identified. Fortunately, areas of high species richness, endemism and restricted species coincided with those where intact seasonally tropical dry tropical forests still exists. These areas should receive high priority in future plans for seasonally tropical dry tropical forests protected areas. It is hoped that this paper will call attention to the need for establishing a network of protected areas in the study area, as has been proposed by previous studies.  相似文献   

Estimation of Deposition Velocities for 85Sr, 131I, 137Cs on Spinach,Radish and Beans Leaves in a Tropical Region Under Simulated Fallout Conditions     

Singhal  R. K.  Narayanan  U.  Gurg  R. P. 《Water, air, and soil pollution》2004,158(1):181-192

Poly dispersive aerosols of SrCl₂, NaI, CsCl having a size distribution of 2.33 m (Activity Median Aerodynamic Diameter, [AMAD]) with a geometric standard deviation of 1.83 m are used for the determination of deposition velocity for ⁸⁵Sr, ¹³¹I and ¹³⁷Cs aerosols on tropical spinach (Spinicia olericia), radish (Raphanous sative) and beans (Phasolous valugeries) plant leaves. The experiments were carried out in a specially designed exposure chamber to simulate deposition under accidental releases of radioactivity in tropical environment. The rates of particles deposition are expressed as a function of plant surface area and of plant dry weight. The deposition velocities obtained are in the range of 10^–6 to 10^–7 m/s. These values differ significantly from those in temperate regions. The lower values for deposition velocities (v _g) for the tropical environment is attributed due to high humidity. Therefore, the deposition of suspended aerosols on leaf surfaces caused by impaction and Brownian diffusion becomes slower in tropical environment and resulted into lower value of deposition velocities.  相似文献   

玉米矮花叶病抗源筛选和抗病育种策略   总被引：5，自引：0，他引：5  

吴建宇  陈伟程  丁俊强  杜彦修 《河南农业大学学报》2001,35(4):308-312

病圃鉴定结合接种鉴定和苗期叶片的ELISH检测结果表明，87份接种材料中筛选出了4份高抗材料，24份抗病材料，26份中抗材料；46份病圃鉴定材料中筛选出9份高抗材料，21份抗病材料，4份中抗材料；5份苗期ELISH检测的材料中鉴定出2份抗病材料，结合血缘追踪发现，热带、亚热带种质以及美国先锋海外种子公司育成的玉米杂交种78599，87001和78698等衍生系中蕴涵着抗病基因，在抗源筛选的基础上提出了抗病与高产结合的育种策略。  相似文献   

加强审稿环节提高热区农业科技期刊质量     

郑慧坚  林家丽  庞振才 《华南热带农业大学学报》2007,13(2):113-116

根据我国热区农业科技期刊发展面临的问题,探讨从审稿环节入手提高热区农业科技期刊学术影响力及期刊质量的途径。  相似文献