Promoting innovation to improve both productivity and sustainability of irrigated farming systems is crucial for the first question addressed within the Sustainable Development Goals process led by the United Nations. This is a complex task that requires methods and processes which include a diversity of knowledge. For this reason, participatory approaches have been increasingly encouraged. A broad range of methods have been developed in the literature. However, debates on the effectiveness of the results, including questions on how different stakeholders influence results and how the context influences platform processes, remain theoretical. In this article, the authors evaluate the results of a participatory diagnosis aiming to identify the constraints and possible innovations to improve agricultural production in the Brahmi irrigation scheme in Tunisia. The process was implemented with individual interviews and focus groups operationalized through two types of platforms, 'Community of Practice (CoP)' and 'Learning and Practice Alliance (LPA)'. We highlighted that both CoP and LPA offer fruitful platforms for the interaction of all stakeholders. However, the results could be biased by the context and the expectations and strategies of powerful participants. Individual interviews are complementary to focus group results, especially in situations where open or latent conflicts exist.