Lessons from 35 years promoting agroforestry trees in Brazil's central Amazon

Since 1975, Brazil's National Research Institute for the Amazon has been involved in the promotion of trees in agriculture. This experience is reviewed, with special attention to participatory research, to arrive at suggestions for research and development (R&D) strategies for underutilized species. Information was collected on all species of potential interest, including exotics. To collect data, farms with rare species were localized and visited. To obtain experience under "real" conditions, a series of on-farm trials were organized. Volunteer farmers chose species and quantities, contributed with land and labor, and were free to manage the plantings in their way. Recommendations are given for the preparation of species profiles containing: (1) a crop's strong and weak points; (2) comparisons of the crop with other options available to the farmers; (3) comparisons of the product with competing alternatives; (4) factors limiting the species' expansion; (5) researchable constraints; (6) recommended sources of planting stock. It is practical to elaborate a set of profiles pertaining to a particular category (e.g., species producing medicines) of interest to a specific group of farmers. Sets of profiles of all potential species can give the necessary overview for the development of a R&D strategy. Major R&D efforts should concentrate on the more promising species. The choice of these species needs review at regular intervals, to maintain flexibility in the program. Many species show significant variability for economically important traits. In these cases, selected material must be used from the very beginning. This can be done by using offspring of superior plants. A part of this offspring can be used for progeny tests. Using single-tree plots, single replicates will be small enough to fit on the land of interested farmers. By culling, some replicates can be transformed into orchards for the production of genetically improved material