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Two plant production-based strategies – biofortification and dietary diversification – have been advocated to overcome micronutrient deficiencies, which are major contributors to morbidity and mortality worldwide. The respective benefits and effectiveness of these two strategies are the subject of controversy. Expanding the scope of this debate beyond the sole nutritional outcomes, and using a food system approach, this interdisciplinary review aims to providing a novel and holistic perspective on the ongoing debate. The literature shows that biofortification can be an effective medium-term strategy to tackle nutritional risk in vulnerable populations in some contexts, but that it also may have negative environmental, economic, and social impacts. Dietary diversification, on the other hand, is known to be a sustainable way to overcome micronutrient deficiencies, bringing with it long-term benefits, including nutritional, and beyond, the provision of ecosystem services. Dietary diversification is however challenging to implement, with benefits that are not immediate. Biodiversity as a basis of human diets is critically important to improving both human and environmental health. Diet diversification through increased mobilisation of biodiversity in food systems deserves much more attention and support in policies for food and nutrition in low- and middle-income countries.

Monospecific banana (Musa spp., AAA group, cv. Cavendish Grande Naine) based cropping systems may present important threats for the environment. The pesticides, used to control plant-parasitic nematodes, fungi (Mycosphaerella fijiensis and M. musicola) and insects (Cosmopolites sordicus), endanger water resource, biodiversity and human health. These risks are magnified in fragile tropical insular conditions of French West Indies (F.W.I.) where inhabited areas, coral reefs and rainforests are interconnected with agrosystems. A model called SIMBA was built to help designing more sustainable cropping systems. SIMBA simulates the major ecological processes of the soil-bananas-nematodes system. This model runs at the field scale with a weekly time-step and simulates over many cropping cycles the heterogeneity of stages of the banana plant population, banana growth and yield, plant-parasitic nematodes population dynamics, water balance, soil structure, and gross margin. Inputs include climatic data and farmers practices via decision-rule processes. A set of agrienvironmental indicators linked to the model were developed to assess the potential risks of erosion and pollution of ground and surface water. SIMBA was calibrated and validated with data from Guadeloupe and Martinique (F.W.I.) and hence allows the evaluation of existing or virtual cropping systems on a multicriteria basis (performances and impacts). Selection of cropping systems is realized by weighting the model's outputs (economical margin and environmental risks) according to a point of view (minimizing environmental risks or maximizing the economic margin with minimum environmental risk). It is used for strategic thinking with farmers and advisers as it provides ex ante assessment of the impact of technological or management innovation in existing bananas cropping systems. It is also a research tool to prototype new cropping systems by testing predefined scenarios or by exploring complex sets of decision-rule

Dans un contexte de contraintes croissantes sur les marchés internationaux comme sur les ressources naturelles, la diversification constitue un enjeu majeur pour les agricultures du Sud. Cet article identifie les principales composantes du processus de diversification et propose un cadre d'analyse de ses différentes facettes, en soulignant la double importance du déterminisme écologique et des opportunités du marché. La définition de la diversification est dans un premier temps précisée et discutée, aux différentes échelles pertinentes (système de culture, exploitation agricole, territoire) et en relation avec les différentes fonctions économiques, sociales et environnementales de l'agriculture. À partir d'exemples issus de situations tropicales de pays en voie de développement ou de départements français d'outremer, les auteurs recensent les différents moteurs de la diversification puis proposent d'aborder la diversification au travers de trois unités d'analyse: les filières, l'espace, l'exploitation agricole.

Après avoir, dans une première partie, précisé le contexte actuel de la diversification agricole dans les pays du Sud et décrit ses principales caractéristiques et ses principaux moteurs, les auteurs abordent dans cette seconde partie le processus de diversification à travers trois unités d'analyse complémentaires : les filières, l'espace, l'exploitation agricole. Les conditions de la diversification à ces trois niveaux d'organisation sont ainsi successivement analysées, à partir d'exemples issus de situations de pays en développement ou de départements français d'outremer. Un ensemble d'outils méthodologiques adaptés pour étudier ou accompagner les processus de diversification agricole est ensuite proposé, mettant l'accent sur la combinaison nécessaire des apports de l'agronomie (approches systémiques, à différentes échelles) et des sciences sociales (évaluation de la compétitivité des filières, économie et sociologie de l'innovation). Des exemples issus de situations concrètes illustrent ces approches multidisciplinaires combinant aspects agronomiques, géographiques et économiques.