INTERNATIONAL TRIAL OF DRY ZONE SPECIES ¹

by

C.E. Hughes
Commonwealth Forestry Institute
Oxford, U.K.

The CFI, in cooperation with national organizations in Central America, has acquired seed collections of a package of dry zone hardwood species suitable for non-industrial purposes such as firewood, posts, forage and other end uses. This seed will be distributed for international species trials, within the framework of the Global Programme for the Improved Use of Forest Genetic Resources, coordinated by FAO.

Small experimental quantities of seed of the species listed in Table 1 are available for distribution free of charge to researchers who wish to participate in the international programme. Twenty-one of the species listed are legumes. Four promising non-legumes are included. The species are all native to dry but not truly arid areas in Latin America with mean annual precipitation in the range 500–1000 mm and a dry season of 5 to 7 months.² They are adapted to lowland areas up to 100 m elevation. All the species are preferred locally for firewood and many satisfy a range of other end uses. Several have particular attributes making them valuable in erosion control.

Several of the species are aggressive, fast-growing colonizers. These are likely to ideal to meet the severe shortages of firewood in harsh dry climates. In less severe environments where firewood is not so scarce the threat of weediness exists and they should only be introduced with care. Four species show particular tendencies to become weeds: Mimosa tenuiflora, Acacia farnesiana, Parkinsonia aculeata and Prosopis juliflora. Clearly some of the lesser known taxa present similar threats.

Legume seeds generally have hard seed coats which inhibit the uptake of water. For quick and uniform germination pre-sowing treatment is necessary. Although numerous techniques have been used, careful calibration of these methods will be necessary for each species. For valuable research seedlots manual scarification by chipping, nicking or filing is recommended.

Requests for seed

Although requests for individual seedlots or subsets of the complete package will be met where possible the bulk of the seed is destined for complete trials. Requests for seed, together with all necessary import permits, should reach the CFI at least three months before the seed is required for sowing. The number of proposed trial sites and species required should be clearly stated. Brief site details of latitude, altitude, soil profile and rainfall and temperature regimes are also useful. Requests should be addressed to: Colin E. Hughes, Research Officer, Unit of Tropical Silviculture, Commonwealth Forestry Institute, South Parks Road, Oxford OX1 3RB, U.K.

Note

The seed will normally be distributed with a phytosanitary certificate enclosed in the package. Special instructions about compulsory pesticide treatments and import permits must accompany each request, allowing extra time for processing the documents if necessary.

The seed is made available without seeking commitments from the recipients. Each collaborator is encouraged to analyse local data and publish results in technical journals. However, many researchers have acknowledged that there is much to be gained from a programme of international cooperation and exchange of information. Consequently the CFI has developed facilities for the computerised storage and retrieval of trial assessment data which are available to all contributors of information. This pooling of data has greatly assisted assessment over a range of environments thus accelerating the process of species evaluation.

If researchers wish to take advantage of these facilities, it is desirable that a standardised experimental design is used and full design details will be supplied at the time of seed despatch.

Table 1 Locations of Seed Collection Sites in C. America

Manuscript received in April 1984

¹ See also pp. 12–17 for availability of seed of additional dry-zone species.