The European Union has been funding scientific and technological research since 1982, particularly in the agricultural field, in support of economic and social development in developing countries (Programmes STD 1, 2 and 3). Under STD 3 a research project is currently studying the functioning of Hevea - based farming systems, involving several partners. The CIRAD-CP Rubber Programming in France (coordinator), the University of Hohenheim in Germany, the Latex Plants Division at IDEFOR in the Ivory Coast, CATH in Clabon and the IRRIs Sembawa station in Indonesia. The aim of the project is to study the phenomena involved in competition for water, light and nutrients within the functioning of temporary intercropping systems combining Hevea with annual food crops, so as to identify the limiting factors and consequently optimize growth and yields in these farming systems.