Germplasm collections of endangered agroforestry tree species: the case of Prosopis africana in the semi-arid lowlands of West Africa

The International Centre for Research in Agroforestry (ICRAF) coordinates a research network in the Semi-arid Lowlands of West Africa (SALWA) in four countries: Burkina Faso, Niger, Mali and Senegal. Prosopis africana, an important agroforestry tree species is seriously threatened in this eco-region. ICRAF organized seed collections of this species for long-term conservation and subsequent utilization by small-scale farmers in the West African Sahel. Prior to the collection, ICRAF, the International Plant Genetic Resources Institute (IPGRI) and International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) organized a planning workshop with collaborating national research institutes. Out of this workshop came a consensus on the strategy, logistics and choice of collection sites. To collect as much genetic diversity of P. africana in the SALWA region as possible, 34 collection sites were selected: 15 in Niger, eight in Mali, seven in Burkina Faso and four in Senegal. The main aim of the collection was to capture the genetic diversity within P. africana before the valuable genetic resources are lost. This paper reviews the methodology and results of the germplasm collection. This revised version was published online in August 2006 with corrections to the Cover Date.     

The state of the art of agroforestry diagnosis and design

Seven years ago the International Council for Research in Agroforestry set out to develop a methodology for the diagnosis of land management problems and design of agroforestry systems. Since then over 60 documents (articles, conference papers and manuals) relating to the D & D methodology have been published by ICRAF and the methodology has been used to develop agroforestry plans and identify research priorities for a wide range of ecological and cultural conditions throughout the tropical regions of Africa, Latin America and Asia. This article reviews the evolution of the D & D methodology and suggests directions for its future development.Ecological Anthropologist, ICRAF     

ICRAF's first ten years

This article is about the institutional development of the International Council for Research in Agroforestry. It follows the Council's history from the initial ideas in the IDRC-sponsored study Trees, Food and People, its formalization in 1977, the early years up to 1980, when the Council was searching for an identity, the expansive years 1981–85, when in-house capability was built up and the foundation laid of the agroforestry discipline, to the present phase, from 1986, when major field research programmes are being initiated. The main emphasis is on the strategies and priorities behind the programmes in the different phases. A summary is given of the Council's development and growth in terms of funding and staffing. In the final section, some thoughts are expressed about ICRAF in the 1990s.Director, ICRAF; Forester     

Systematic designs for field experimentation with multipurpose trees

Systematic field layouts are especially useful with MPT species for examining plant responses e.g. to density stress, and where a wide range of treatment levels are needed because of lack of previous data. Examples of a fan and a parallel-row layout are given (with suitable sets of dimensions) and the development of parallel-row designs for management trials and mixed cropping is illustrated.A revised version of ICRAF working Paper No. 12 which has been incorporated into Research Methodology for the Exploration and Assessment of Multipurpose Trees (Ed. P.A. Huxley), 1984. ICRAF, Nairobi — Financial support for the latter publication was provided by the U.S. National Academy of Sciences/National Research Council by means of a grant from the U.S. Agency for International Development.     

ICRAF's multipurpose tree and shrub information system

Woody perennials are vital components of agroforestry systems. However, the state of knowledge about most of the large number of useful species is inferior to that about other components in such systems. In order to close this gap and expedite research, ICRAF has built up a multipurpose tree and shrub information system. The recommendations of an international workshop on multipurpose tree germplasm, organized by ICRAF in collaboration with CFI and IBPGR, have been instrumental in either encouraging the pursuance of activities already started or initiating new projects. In its endeavour to serve those institutions and individual scientists who require information on multipurpose trees, ICRAF has established a Multipurpose Tree and Shrub Data Base and compiled and published a Multipurpose Tree and Shrub Seed Directory. As by-products of these two core activities, a number of related projects have been carried out, including the development of a rapid appraisal methodology for selecting priority species for further development, the preparation of multipurpose tree and shrub crop sheets, and an inventory of MPT-related data bases. In a considerable number of publications the concepts and objectives of these activities have been explained. More than 140 information requests in multipurpose trees have been answered with the help of the Multipurpose Tree and Shrub Data Base and the information gap concerning germplasm availability has been closed by the publication of the Multipurpose Tree and Shrub Seed Directory.Senior Research Scientist, ICRAF     

Using sap flow gauges to quantify water uptake by tree roots from beneath the crop rooting zone in agroforestry systems

Grevillea (Grevillea robusta A. Cunn.; Proteaceae) is used in agroforestry in many areas of the highlands of East and Central Africa, and is reported to be mainly deep rooted, with few shallow roots and correspondingly low levels of competition with associated crops for water and nutrients. To examine the extent of below-ground complementarily in water use between grevillea and cowpea (Vigna unguiculata L.; Leguminosae), experiments were carried out at the International Centre for Research in Agroforestry (ICRAF) Field Centre at Machakos, Kenya. Sap flux was measured using heat balance gauges attached to the stems of young grevillea trees (10–18 months old), both before and after excavating the crop rooting zone (upper 60 cm of soil) around the stem base, in order to establish the capacity of the grevillea to extract water from below this zone. After excavation, the trees maintained sap fluxes of up to 85% of the unexcavated values, suggesting a high degree of below-ground complementarity.     

The ICRAF approach to international cooperation

At present ICRAF international cooperation channels the Council's contribution to efforts by national and international research institutions in both the generation of agroforestry technologies and person-power development. This paper attempts a critical evaluation of the evolutionary process that led ICRAF collaborative activities from their initial role of creating opportunities for testing methodologies to the on-going networking stage.Two stages are distinguished in the initial development phase; the one contributing to the building of an institutional capability (more in-house cooperation), and the follow-up stage where activities were aimed at establishing a basis for continuous collaboration with partner institutions.The present networking phase, with an African focus, is based on the assumption that institutional complementarity is the appropriate scheme to overcome the effect of constraints prevailing in the continenta on the generation of appropriate agroforestry technologies. In this context, an ecozone scope, integrated planning and a network organizational structure are proposed as pillars of an ICRAF strategy to achieve complementarity in agroforestry research for development.Head, Collaborative Programmers Division, ICRAF     

Forever amber a story of the secondary wood components

Summary From prehistoric periods, mankind used tree exudates and extractives of various woods and barks and these were at times of major commercial importance. Only amber, tannins, oleoresins and rubber continue to be significant. The study of exudates and extractives has provided a major part of the foundations of organic chemistry and aspects of plant biochemistry such as biosynthesis and chemotaxonomy. The polyphenols in the Eucalyptus genus and those formed in different tissues of the tree stem illustrate the alternative pathways existing in the cells and the complexity of biosynthesis. Basic studies have provided understanding of means of alleviating numerous problems encountered in the industrial use of wood. Attension is drawn to the continuum of development and the contribution of many disciplines. Future studies will be mainly concerned with the control of the formation of secondary components in plantation species, the improvement of quality standards of products and the collection of basic data relevant to biotechnology and other fields. Developments will be dependant on the support of those who are not professional workers in the field.The Academy Lecture presented on 24 April, 1985 at Pretoria, South Africa to Fellows of the International Academy of Wood Science and participants of the Symposium Forest Products Research International — Achievements and the Future. The Lecture was illustrated with many coloured slides and is condensed in this publication. Reprints of the unabridged version are available from the author     

Agroforestry Tree Seed Production and Supply Systems in Malawi

A sustainable agroforestry tree germplasm supply system is vital to resource-constrained smallholder farmers who depend on agroforestry to improve the productivity of their farm enterprises. Successful adoption of agroforestry hinges on the development of a sustainable agroforestry tree germplasm supply system. This paper reviews the agroforestry tree seed supply system in Malawi, with a view to determining its sustainability and quality. Currently, more than 90% of the documented agroforestry tree seed distributed to farmers is produced by smallholder farmers collected mainly from scattered farmland trees, the remainder being produced from seed orchards and seed stands owned or controlled by research organizations. Three organizations—namely the Land Resources Centre (LRC), National Tree Seed Centre (NTSC) of the Forestry Research Institute of Malawi (FRIM) and the World Agroforestry Centre (ICRAF)—were identified as major procurers of agroforestry tree seed produced by smallholder farmers. Agroforestry germplasm is distributed to farmers by non-governmental organizations (NGOs) and government agricultural and forestry extension departments. The procurement and distribution of germplasm to farmers is in general effective. The major challenge to sustainability of agroforestry tree germplasm distribution in Malawi is dependence on donor funding. The agroforestry tree seed system is, to some extent, sustainable with regards to production, although the genetic quality of the germplasm is low. Germplasm storage facilities at national level are available and possibly adequate, but knowledge and information on effective low-cost tree germplasm storage systems at household level are limited. Sustainability could be enhanced by strengthening of grass-root organizations involved in tree seed production to institutionalize the distribution through farmer–farmer exchange. There is also a need to support the development, promotion and adoption of low-cost tree germplasm storage facilities by smallholder farmers.     

Fluctuating Fortunes of a Collective Enterprise: The Case of the Agroforestry Tree Seeds Association of Lantapan (ATSAL) in the Philippines

The Agroforestry Tree Seeds Association of Lantapan (ATSAL) in Bukidnon province of Mindanao, Philippines, was organized in 1998, facilitated by the World Agroforestry Centre (ICRAF). Farmers were trained on germplasm collection, processing and marketing of agroforestry tree seeds and seedlings. ATSAL has been marketing various tree seeds and seedlings with apparent success, and has provided training on seed collection and nursery management to farmers, government technicians, and workers from non-government organizations. This paper reports initial results of a continuing study to assess the effectiveness of ATSAL’s marketing strategy, including group dynamics, and the issues and challenges the group faces. It was found that during the first 2 years, ATSAL’s market share of highly demanded timber tree species grew rapidly, thus helping to disseminate widely these important species among farmers. ICRAF’s technical back-up was an advantage, increasing the Association’s market credibility. Subsequently, ATSAL extended its market to the central Philippines, but failed to meet the demand for seeds due to organizational limitations. Market competition exists, where a non-member was able to take a larger market share than was the group. Nonetheless, ATSAL has established its name as a viable community-based seed and seedling producer, maintaining a stronghold in local and regional markets. Collective action is important for smallholders to gain market access, but is unlikely to sustain sales. Facilitating smallholder collective action is essentially an arduous task, requiring the supporting agency to hold a firm grasp of market realities, to invest in the maintenance of collective action, to provide continuous technical back-up, and to ascertain the conditions that make collective action succeed.     

Economics of agroforestry

Although from the start ICRAF recognized the importance of the socio-economic dimensions of agroforestry land-use systems, it was only five years after its official commencement that an economist was added to the staff. During the last five years no attempt has been made to create a separate Economics Department with its own programme. Rather, the emphasis has been on supporting on-going ICRAF activities by trying to make “economics’ an integral part of eachof these activities.

Nevertheless, in summarizing these efforts, five major areas of work can be identified:
1. Economic concepts;
2. Methods and tools for economic assessment;
3. Economic information gathering;
4. Economic analysis proper;
5. Training and dissemination.

The achievements in each of these areas, as well as some ideas on possible trends, will be summarized in this paper.     

The potential of alley farming in humid West Africa — a re-evaluation

Previously published hypothesis concerning the potential impact of alley farming on maize yields are re-examined relative to the humid regions of West Africa. When more realistic assumptions regarding the availability of organic nitrogen are used, it is concluded that alley farming may have potential in a wider range of maize yield environments in West Africa than previously proposed. A pragmatic approach to alley farming research is proposed, and the importance of on-farm research in the development of farmer friendly alley farming is stressed.(Former Agronomist, International Livestock Centre for Africa, P.M.B. 5320, Ibadan, Nigeria)     

The contribution of agroforestry to world forestry development

Agroforestry with its outstanding variety of systems and technologies has been practiced in all parts of the world since times immemorial. Its worldwide recognition, scientific promotion and application in rural development strategies in the tropics, however, ‘exploded’ with two events: the foundation of the International Council for Research in Agroforestry (ICRAF), 1977 and the Eighth World Forestry Conference in Jakarta, 1978. This is important to be recalled at the occasion of the Ninth World Forestry Congress to be held in Mexico this year. Agroforestry's holistic approach to solving land use problems under prevailing conditions and constraints of different humid, semiarid and mountainous regions has gained importance and produced first remarkable results with regard to increasing the human-ecological carrying capacity. Forestry is gaining from the newly promoted strategies of integrated land use in various ways: less pressure on forest resources and thus less destruction of forest vegetation, additional lands for wood production outside the forest estate, cooperation instead of confrontation with other target groups, and an expanded multiple-use concept increasing the value of marginal forest lands. Agriculture and livestock management are improved by various environmental benefits of the forest component and by the availability of forest products within agroforestry systems. First achievements over the past seven years have been encouraging in many instances. Much more, however, remains to be done in future.     

西双版纳现有混农林系统的主要模式

本文在对西双版纳现有混农林系统进行广泛调查的基础上,根据国际混农林研究委员会(ICRAF)P.K.R.Nair的分类方法,将其进行了分类和评价。结果表明,该地区现存混农林系统的模式极为丰富,并以经济植物为主体的模式占较大优势。这些模式,有的已经发挥出较好的生态、经济和社会效益,有的仍处于实验阶段,有的则对合理利用当地自然资源造成不良的影响。提出了必须合理开发利用当地自然资源,积极创立和引进以粮食作物为主体的混农林系统模式的见解。     

Pattern of soil moisture depletion in alley cropping under semiarid conditions in Zambia

The pattern of soil moisture changes was studied during a cropping season in an alley cropping experiment of maize withLeucaena leucocephala andFlemingia macrophylla at the SADC/ICRAF Agroforestry Research Station in a semiarid region near Lusaka, Zambia (28°2956 East and 15°2132 South). Soil moisture potential was monitored at regular intervals using tensiometers installed at 15, 30 and 45 cm depths in fertilized and unfertilized alleys within the double hedgerow, and the first, second and third rows of maize in the alleys.Soil moisture moved mostly towards the top horizon during very dry conditions. Alleys that had received a combination of fertilizer and hedgerow prunings depleted more moisture than those that had only hedgerow prunings. There were no differences in moisture utilization pattern between leucaena and flemingia hedgerows. The hedgerows depleted the same amount of moisture as the maize plants. However, during dry conditions, there was a higher soil moisture content under the hedgerows than in maize rows, indicating that there was no apparent competition for moisture between the hedgerows and the maize plants.     

Toxic effects of annonaceous acetogenins on <Emphasis Type="Italic">Oncopeltus fasciatus</Emphasis>

From an Argentine collection of Annona cherimolia and a Bolivian collection of Annona montana (Annonaceae), the acetogenins, squamocin, molvizarin, itrabin, almuñequin, cherimolin-1, annonacin, annonacin-A, densicomacin-1, cis-annonacin-10-one and murihexocin-A, were obtained to study their toxicity against the cotton pest Oncopeltus fasciatus (Hemiptera: Lygaeidae). Topical ventral application of O. fasciatus nymphs with solutions of the mentioned acetogenins produced acute and delayed mortality.     

Improving the collection and germination of West African <Emphasis Type="Italic">Garcinia kola</Emphasis> Heckel seeds

Garcinia kola is highly used as chew-stick for dental care in West Africa, but it is nearly commercially extinct in nature. To help find methods to increase rate and percentage of germination, we investigated its seed germination responses by using several collections and pre-treatments. Seeds processed from 6-week old green fruits did not germinate, whilst those of 10-week old partly-mature, at the intermediate stage through full development, germinated 46%. Seeds from orange mature fruits reached maximum 54–62% germination. Radicles emerged 6 weeks after sowing and normal germination with emergence of the primary single shoot growth occurred after 12 weeks. There was no significant difference (P ≥ 0.05) between germination responses of seeds from Ghana and Cote d’Ivoire. Seeds did not germinate when dried to below ca. 30% MC. De-coating seeds or soaking intact seeds in a 70% ethanol solution increased germination to 82–92%, and also increased germination rate; however germination was not uniform. Because difficulties in germinating these seeds stem from the physical presence of the seed coats and the slow growth of the embryos contained therein, we recommend that fresh seeds from mature fruits be de-coated and immediately sown in preferably, an aerated medium (e.g., sawdust) for cultivation.     

国内外无患子属种质资源研究进展

无患子属（Sapindus L.）种质资源是无患子产业发展的基础,种质资源研究可为探讨无患子属的起源、进化、分类、资源保护与利用、良种选育、高效栽培等提供科学依据和基础。文中综述了国内外无患子属分类、分布及亲缘关系,种质资源的收集、保存与评价,种质资源多样性等方面的研究进展,得出如下结论:1）世界上无患子属树种共13种,我国分布4种1变种;2）我国多个研究团队收集、保存无患子属种质资源近1 000份,以假种皮皂苷、种子脂肪酸利用为目标,筛选评价出性状优异的9个种源、7个家系和54株优树;3）无患子种质资源在表型、假种皮皂苷、种子脂肪酸、遗传等方面多样性丰富,并受环境因子极大的影响,根据遗传多样性分析推测我国无患子起源于自然分布区中部并向四周扩散。研究认为,目前研究仍存在种质资源收集不足、缺乏对该属树种系统研究和无优良品种推出等亟待解决的问题,提出应加强无患子属分子生物学基础研究、以居群为单位加强无患子属种质资源收集和评价力度、加强良种选育和高效培育技术以及国际合作研究等建议,以期为无患子产业可持续发展提供有力支撑,促进无患子属种质资源的开发利用。     

基于水青树叶表型性状的核心种质资源库构建策略

[目的]为了更好地构建水青树核心种质资源库,本文以161个水青树种质为试材,利用叶表型性状的遗传变异数据,对其构建方法进行了探索。[方法]首先,采用欧氏距离和瓦尔德法对所有个体进行逐步聚类;然后,设定10个取样比例(10%、15%、20%、25%、30%、35%、40%、45%、50%、55%),分别用随机取样策略、偏离度取样策略和位点优先取样策略筛选出与之对应的核心种质资源库。将这3种不同取样策略构建的核心种质资源库进行比较,从而筛选出最适种质资源。[结果](1)三种取样策略中,位点优先取样法明显提高了其种质资源库的方差差异百分率(VD)、变异系数变化率(VR)和极差符合率(CR),且45%是最适合构建水青树核心种质资源库的比例;(2)对种质资源核心库不同数量性状进行t检验,其累计贡献率达到82%以上。[结论]在欧氏距离结合瓦尔德法聚类条件下,位点优先取样策略是构建水青树种质资源核心库的最佳方法。