Extracts from Circular Letter No. 13 (April 1981), Dansih Seed Centre, Humlebaek1
In the mid and late 1970s, seed from 37 provenances (44 seedlots) of Gmelina arborea was distributed by the Seed Centre at Humlebaek, Denmark for the establishment of international provenance trials on a total of 74 sites in 22 countries. The countries participating in the trials are: Australia, Bangladesh, Belize, Brazil, Cameroon, China, Colombia, Ghana, India, Indonesia, Ivory Coast, Malawi, Malaysia, Mexico, Nepal, New Herbridies, Nigeria, Papua New Guinea, Senegal, Solomon Islands, Thailand and Venezuela.
Progress reports from participants indicate that the trials have generally been successfully established. Also, measurements and assessments have been carried out in some of the trials.
Germination of seed showed marked differences between nurseries. These differences are thought to be due to: (1) seed condition primarily as affected by handling during transport to participants; (2) handling and treatment in customs and quarantine stations; (3) conditions in the nursery during germination and growth; (4) differences in assessment dates and/or differences in assessment principles; and (5) experience with Gmelina arborea and general skill of the nursery staff. Average germination (a mean of results reported from 16 nurseries) was 30%.
Survival, as recorded in 9 trials after 4 – 12 months, was consistently high, in average 96 %. However, it is not always known if replacements have been included or omitted from the figures presented.
Height growth, recorded at ages 3 – 30 months: overall mean (assuming linear relationship between growth and time) was 275 cm per year; there were pronounced differences between sites.
Tree form: there were pronounced differences between sites.
The main conclusions drawn in the Circular Letter are that much more information must be collected before a comprehensive analysis of results of the provenance trials is possible. It is preliminarily proposed that a joint evaluation of trials be made using uniform methods of assessment, and that representatives of the Seed Centre at Humlebaek visit participating countries to assist in this evaluation.
Note: Frequent reference is made in the Circular Letter to technical findings in Brazil, published in the following article: Woessner, R.A. (1979). Large-scale production of Gmelina arborea Roxb. seed; a case study. Commonwealth Forestry Review 58(2).
