A grand challenge for agriculture is to adapt current intensive or semi-intensive production systems in the face of global change. Indeed such systems need to be re-designed to cope with increasing drastic environmental changes, especially increasing frequency of extreme and hazardous climatic events. Traditional genetic improvement is based on the built-in of ideotypes characterized by reduced, or null, genetic variability (pure lines) and grown in monoculture. Even if efficient and necessary, this approach cannot fully respond to future avenues related to the sustainability of agronomic covers and the interannual stability of their biomass production in the face of increasing intra- and interannual variability of water deficits. Current production systems are characterized by reduced sown genetic diversity via the widespead use of species grown in monoculture only, while several ecological studies have demonstrated the plus-value of taxonomic and genetic diversity for the stability of biomass production in response to environmental changes. Promoting specific diversity of agricultural covers may allow to better coping with environmental hazards while challenging environmental avenues for agriculture (reduction of inputs, maintenance of wild biodiversity etc.). Here is the working hypothesis for PRAISE. The use of cultivated species in mixture implies important changes for varietal selection. Genetic improvement of cultivated species for a use in mixture also remains to be developed. Indeed the response of a variety grown in isolation or in mixture may be decoupled given the complex interaction effects among neighbouring plants within a mixture. To reach these objectives, we advocate the need for a drastic change of paradigm for varietal selection. Accounting for genotypic interactions within- and among-species, via the analysis if intra- and interspecific trait distribution, is a necessary step for a renewal of selection schemes so as to improve the production and sustainability of crops in the face of environmental hazards. PRAISE is focused on sown temporary and plurispecific grasslands. This type of covers plays a major role as part of sustainable agriculture. Up to now, the genetic (within- and among-species) diversity of such a cover has been poorly examined and exploited. PRAISE aims at studying and promoting this diversity. The overall goal of PRAISE is to pave the road of a renewed genetic improvement of grassland species involved in mixture based on genetic and ecological knowledge in a context of increasing environmental hazards. More specifically, we aim at: (i) identifying the best varietal composition of mixtures, and the related genetic and ecological conditions of application, which maintain high and stable production of plurispecific grasslands over time; (ii) provide the theoretical bases of an innovative selection schema of forage grassland species for a use in mixture. PRAISE is a pluridisciplinary project at the crossroad of quantitative genetics, ecophysiology, functional ecology and population and ecology. Together, we will develop a renewed selection schema involving genetic and taxonomic diversity. As a perspective, this schema may be applied to other types of cultivated species, including field crops which are also facing big environmental challenges.