COLLECTION OF GLIRICIDIA SEPIUM SEED IN CENTRAL AMERICA FOR PROVENANCE TRIALS

by

B. Chang and H. Martínez
Department of Renewable Natural Resources
CATIE, Turrialba
Costa Rica

INTRODUCTION

Traditionally Gliricidia sepium (Jacq.) Steud. is one of the most popular multi-purpose species in Central America. It is used for live fences, to provide shade for coffee and cocoa and for production of wood, fodder, honey and human food.

Its ease of reproduction, both by seeds and vegetatively, the ease with which it can be established and managed, and its flexibility in a broad range of ecological conditions are widely known. This has made it one of the species most commonly planted in urban areas, as well as by farmers with small or medium resources.

The traditional propagation method is by cuttings of different sizes obtained from clonal plantations representing a small number of genotypes. The dangers of using such narrow germplasm bases are well known. Since the species is naturally distributed in Central America (Little, 1983), it is still possible to locate natural stands which could and should be used as germplasm sources to obviate the risks involved in repeated vegetative propagation. It is therefore desirable to draw upon a broad range of germplasm sources in order to widen the genetic base of the populations in use and also to select the best parent stocks for a broad range of climatic, soil and utilization conditions.

NATURAL DISTRIBUTION

The species is distributed naturally from southern Mexico, through Central America, to Colombia, Venezuela and Guyana. Its altitudinal range is from sea level to 1,600 m (in Central America it has been found growing wild up to 1,400 m in Guatemala); it grows on different soil types such as sand and sandy, clayey, calcareous, eroded and stony soils. Good natural stands have been observed in areas with an annual rainfall of 800 mm to 2,300 mm.

PHENOLOGICAL OBSERVATIONS

Flowering in G. sepium appears to be related to the beginning of the dry season, so that its onset varies according to latitude. In Guatemala, where the dry season starts at the end of October, flowering begins in January and extends until early March, while in Costa Rica, where the dry season begins at the end of November, flowering starts in February and continues until April.

In Guatemala, as in the Pacific area of Nicaragua, seed is collected from the end of February until the beginning of April, with a peak in mid-March. In Costa Rica collection begins at the end of April and ends early in June. In Colombia, July has been reported as the flowering season and September as that of seed collection.

LOCATION OF STANDS FOR SEED COLLECTION

Five natural stands were identified in Costa Rica for seed collection in 1984. Because of an abnormal storm accompanied by strong wind in mid-April 1984, which affected the fruits, seed was unobtainable from three of these. Since seed could only be harvested from the remaining two coastal stands (lots 1812, 1816) it was decided to collect seed from live fences (of which there are more than 20 km), selecting one out of every 15 to 25 trees as a seed tree, provided that it bore seeds. The live fences from which collections were made were sub-divided to represent four “provenances”. The same method for obtaining seeds was used in Guatemala (lot 1868) in the hope of obtaining wide variability. In all, seed was collected from a total of more than 1,200 trees representing 24 “provenances”. ¹ Of these “provenances”, six are from live fences (five in Costa Rica, one in Guatemala), and eighteen from natural stands (sixteen in Guatemala, two in Costa Rica) (see Table 1 and map).

FUTURE RESEARCH

1. Range-wide tests. To determine the variation between provenances (Burley, Wood and Lines, 1979) all the provenances collected in different ecological conditions (altitude, precipitation, temperature and soils) in Central America will be tested. In Guatemala the work has been started at four sites; this test will be complemented by studies on behaviour in the nursery. After selecting the most promising provenances for the different areas represented by the test sites, steps will be taken to ensure abundant seed supplies.

2. Identification of other seed sources in Central America. Seed will be collected from natural stands in Honduras, El Salvador and perhaps two sites in Nicaragua and one site in northern Guatemala.

3. Conservation of seed sources. The provenances from natural stands in Costa Rica come from areas protected by government laws, while live fences, because of their value to the owners, are unlikely to be destroyed. In Guatemala the natural stands are located on state lands and their conservation can be ensured through coordination with the Servicio Forestal Nacional (National Forest Service).

REFERENCES

Burley, J., Wood, P.J. and Lines, R. 1976 A Guide to field practice. In Burley, J. and Wood, P.J. (Editors). A manual on species and provenance research with particular reference to the tropics. UK, Oxford. pp. 83–107. Tropical Forestry Papers No. 10.

Little, E. 1982 Common fuelwood crops. Communi-Tech Associates, West Virginia, USA. (354 pp.)

Table 1. DATA FOR GLIRICIDIA SEPIUM PROVENANCE COLLECTIONS

* Seed obtained from live fences sampled as described in text.

** Old collection, made jointly by the Instituto Nicaraguense de Recursos Naturales y del Ambiente (IRENA) and the Banco Latinamericano de Semillas Forestales (BLSF) of CATIE.

NOTE: It is expected that additional collections will become available from the Dirección de Recursos Naturales Renovables (RENARE) in Panama and IRENA in Nicaragua.

¹ Persons interested can purchase seeds by contacting the Banco Latinoamericano de Semillas Forestales, Departamento de Recursos Naturales Renovables, CATIE, Turrialba, Costa Rica.

Manuscript received July 1984