by
A.S. Ouedraogo, L.M. Somé, S. Bance and R. Bellefontaine
Direction des Semences Forestières
Ministère de l'Environnement et du Tourisme
Route de Kaya, B.P. 2682
Ougadougou, Burkina Faso (West Africa)
Starting from February 1984, wide-ranging seed collections of Sahelian and Sudanian Zone forest species have been carried out by the Direction des Semences Forestières (DSF) in Burkina Faso. These collections were started by the predecessor of the Direction des Semences Forestières (DSF), the “Centre de Semences Forestières” which was created in July 1983.
The main objectives of DSF are:
At a national level:
to meet present demands for forest seed in the country, supplying on-going institutions and development projects with seed of a wide range of species of high physiological and genetic quality;
to gradually move towards furnishing genetically improved reproductive materials;
to contribute towards field training in order to improve technical know-how, with special reference to nursery techniques.
At a regional level:
to gradually extend activities to neighbouring countries in exploration, selection, seed collection and distribution, and training;
to benefit, through experiences gained, other countries which wish to create or reinforce their seed units and to establish, in collaboration with such countries, a network for the exchange of information and reproductive materials.
The activities of DSF can be divided into three main programmes:
1. Exploration, selection and management of seed production areas, seed collection seed distribution
1.1 Exploration
Activities include exploration of the natural range of a number of species, aimed at testing intraspecific variation in provenance trials (present activities focus on Acacia albida and Parkia biglobosa), and to identify phenotypically superior provenances and/or provenances of potential interest from an ecologial point of view.
Approximately 300 seed stands were identified between February 1984 and March 1985.
1.2 Selection
The selection of seed stands is based on size, location, homogenity, age, phytosanitary state, wood production (height, volume), form of trees and, in some cases, technological quality and profuse fruiting.
1.3 Management of seed production areas
In order to satisfy the needs for seed, a network of seedstands has been created in the country; the stands identified are managed for high seed production, as a first step towards improved seed supply.
The best stands are legally protected by Ministerial order. Pending results from provenance trials, which will give better indications on the best collection areas, collections of DSF are concentrated on these phenotypically good stands (except for collections for research, which cover a wider range).
Each seedstand is thinned leaving only the best phenotypes for seed production and collection.
1.4 Seed collection
Collection is made from a minimum of 25 to 30 select mother trees, spaced at least 100 m from each other.
DSF's Seed Collection Form includes information on exact geographic location, and gives data on climate and soils, associated vegetation, vegetation formations and phenology; it also documents the scientific and vernacular names of the species and gives a description of the mother trees, the number of trees collected from, phenological stage, date of collection, collection method and the name of the officer in charge.
Some collections are kept separate by mother tree.
By the end of March 1985, 422 seedlots of 63 species (among which 15 are of introduced species) had been collected, amounting to a total of approximately 2000 kg of seed.
1.5 Seed distribution, sales and assistance to users
By the end of December 1984, 265 seedlots of 31 species (among which 13 of introduced species), amounting to a total of 366 kg of seed, had been distributed by DSF.
Thus, DSF was able to satisfy the seed orders of 25 national development programmes, 10 African institutions (in Benin, Cap Verde, Ivory Coast, Mauritania, Madagascar, Mali, Niger, Guinea Bissau) and 2 European customers (France, Netherlands).
This shows the great existing demand of seed as orders were received even from abroad although no publicity has, to date, been made.
The first Seed Catalogue of DSF will be available in June 1985, and can be ordered from the address given on the previous page. Species of which seed was available 1 May 1985, are listed in Annex 1.
DSF, working as a bridge between research and development programmes, permits the Centre to give considerable support to institutions and development programmes, such as:
selection of species;
utilization of the best-adapted provenances;
dissemination of research results for practical applications in the field through direct contact with field staff, publication of technical notes, and the organization and encouragement of training seminars, courses and extension activities.
2. Seed handling, physiology, technology, storage, phytopathology
2.1 Seed handling
DSF handles relatively large quantities of seed; in this work it seeks to use efficient but at the same time economical methods of seed handling.
High standards are kept for collection, extraction and cleaning of seeds; some research has also been undertaken to determine the best techniques for depulping of fleshy fruits.
2.2 Seed physiology, technology
Seed testing comprises:
moisture content;
germination (in ambient temperature, in the laboratory and in the nursery)
purity.
After December 1984, the above tests have been carried out as a routine in all seedlots handled. Special attention is paid to research on seed technology and physiology. In order to determine, for each species, the best and easiest method of pre-treatment of the seed, to break the dormancy, 13 different methods are presently systematically tried and tested under controlled conditions.
Tests carried out for a number of important species in an incubator (phytotrone) allows research in optimal conditions for germination, controlling day and night temperatures, light intensity and light quality.
The results from research activities listed above are transmitted to cooperating institutions and development programmes in the form of advise on the physiological conditions of seedlots distributed and on optimal pretreatment for rapid and homogeneous germination. This allows nurseries to economise (e.g. seed quantities, watering) and to more efficiently carry out selection at the nursery level.
2.3 Seed storage
Storage is carried out in three types of conditions:
above zero cold storage. At the end of 1984, 2012 kg of seed was stored in a cold room with a capacity of 27 m3, at a temperature between +2 and +4°C, and relative air humidity controlled at 25–30%; through the use of silicagel, humidity can be further reduced for given species;
below-zero storage. Certain species are stored in a deep freezer, without control of air humidity, which will thus be somewhat higher than above;
in ambient temperature in the laboratory. Some research seedlots are kept in these conditions to study the variation in loss of germination over a given time in different species.
Research on storage combined with stratification (notably Azadirachta indica), is also underway.
It has been found that, for a numerous species, it is possible to store the seed after it has been pre-treated with concentrated sulphuric acid (97%), washed with water and dried. Research is also underway on alternatives to acid pretreatment of seed.
2.4 Phytosanitary considerations
Work has concentrated on:
determination of optimal seed collection season to minimize insect damage;
studies on stored seed;
studies in provenance trials;
studies in protected seed stands.
3. Evaluation of reproductive material, vegetative propagation, follow-up activities in nurseries 1
3.1 Establishment and evaluation of provenance trials
In July 1984, a provenance trial of Acacia albida comprising 6 provenances from Burkina Faso, was established at Gonsé, 25 km from Ougadougou. The design used was Randomized Complete Blocks with 4 replications and 49 trees per plot.
A similar trial, using the same design, was established with 8 provenances of Parkia biglobosa.
In July–August 1985, provenances of Acacia albida, Parkia biglobosa and Leucaena leucocephala from a number of countries, will be tested in the field.
3.2 Follow-up activities in nurseries
Follow-up activities are carried out in 10 nurseries throughout the country, among which 5 “priority nurseries” receive special attention.
The objective of these activities is to assist nursery staff in the application of optimal methods for the production of sufficient quantities of nursery stock.
Training has been given to 40 nurserymen through two seminars of 5 days each. Additional seminars on the same lines, are planned for the future.
3.3 Vegetative propagation
A programme for the production of cuttings under cover, is planned for 1985. Activities will start shortly on Acacia albida and Parkia biglobosa.
Conclusions
The activities outlined above show the necessary steps followed and considered in setting up a comprehensive seed programme, as well as priorities and constraints encountered. The main task for the future is to gradually improve the work programme of DSF, based on acquired knowledge.
Already now one can note the tangible benefits that accrue to institutions and development programmes in the country which, thanks to DSF, can count on availability of sufficient quantities of high quality seed of a large range of species. This encourages more ambitious forestry programmes and, at the same time, with sufficient planting stock available, enables a strict selection for the best plants, already at the nursery stage. Consequently survival as well as growth of the plantations are improved leading to better success of forestry operations in the Sahel.
The long-awaited creation of a specialized seed centre in the Sahel allows us to view the future of forestry in the region with increased confidence.
ANNEX I
Direction des Semences Forestières, Burkina Faso
List of species available as of 1 May 1985
Acacia albida
Acacia dudgeoni
Acacia dunii
Acacia gourmaensis
Acacia macrostachya
Acacia nilotica var adansonii
Acacia nilotica var tomentosa
Acacia polyacantha var campylacantha
Acacia raddiana
Acacia senegal
Acacia seyal
Adansonia digitata
Afrormosia laxiflora
Afzelia africana
Albizia chevalieri
Albizia lebbeck
Anacardium occidentale
Anogeissus leiocarpus
Azadirachta indica
Balanites aegyptiaca
Bauhinia rufescens
Bombax costatum
Boscia senegalensis
Butyrospermum parkii
Cassia arbunda
Cassia siamea
Cassia sieberiana
Ceiba pentandra
Combretum aculeatum
Combretum glutinosum
Combretum micranthum
Dalbergia sissoo
Daniellia oliveri
Delonix regia
Detarium microcarpum
Detarium senegalensis
Dichrostachys glomerata
Diospyros mespiliformis
Elaeis guineensis
Entada africana
Erythrina senegalensis
Eucalyptus camaldulensis
Eucalyptus citriodora
Gmelina arborea
Isoberlinia doka
Jatropha curcas
Khaya senegalensis
Lannea microcarpa
Leucaena leucocephala
Moringa pterygospermum
Parkia biglobosa
Parkinsonia aculeata
Piliostigma reticulatum
Piliostigma thonningii
Prosopis africana
Prosopis juliflora
Pterocarpus erinaceus
Pterocarpus lucens
Saba senegalensis
Sclerocarya birrea
Tamarindus indica
Tectona grandis
Terminalia avicennioides
Terminalia mantaly
Ziziphus mauritiana
Article received May 1985
