02578naa a2200157 a 450000100080000000500110000800800410001910000170006024500590007726000090013652021360014570000180228170000200229970000170231977300840233616518292004-04-05       1998    bl uuuu     u00u1 u    #d1 aALLEM, A. C.  aThe value of aggregation of Manihot genetic resources.  c1998  aAbstract: The valuation of biological diversity comprises two distinct schools of thought, one utilitarian that prizes the economic application of species, and another that indistincty prizes all biodiversity "per se". Genetic resources are associated with economics while biodiversity, as non-resources, relies on philosophy and ethics to claim an existence value. Genetic resources are part of the biological diversity. In this paper we aim at a distinction between genetic resources of Manihot and the biodiversity of the genus. This was achieved through a review of the pertinent literature. Genetic resources of Manihot encompass those plants which have the potential to generate an economic revenue, to secure man 's food needs or, however playing a minor role, accrue to the machinery of production. Thus regarded, only six South American species of Manihot, besides a hybrid, were found to qualify as true genetic resources. The investigation revealed that genetic resources of Manihot fall naturally under the following five headings. 1. Food Crops, represented by cassava (Manihot esculenta) and tree cassava (a putative hybride between M esculenta and M glaziovii); 2. Regular Gene Suppliers of Breeding Programmes, represented by M esculenta ssp. flabellifolia, M glaziovii. M dichotoma, and tree cassava; 3. Minor Rubber Producers, represented by M caerulescens, M dichotoma, and M glaziovii; 4. Animal Feed Species, represented by M esculenta and M glaziovii; 5. Ornamental Plants, represented by M grahami and M esculenta. Recent reassessments estimate some 75 species for the entire genus. A good deal of such species have been used in diverse scientific studies but these are best regarded as components of the biological diversity rather than genetic resources. The reason is that if we do not restrict the scope of valuation, all species of economics genera become resources. Finally, we discuss the merit of recognizing a sixth category represented by species related to the ancestry of cassava. This select group boasts a pervading cultural appeal and attracts the interest from other sectors of the community.1 aMENDES, R. A.1 aSALOMÃO, A. N.1 aBURLE, M. L.  tRevista Brasileira de Mandioca, Salvadorgv. 17, p. 11, nov., 1998. Suplemento.