Crop adaptation to climate change requires accelerated crop variety introduction accompanied by recommendations to help farmers match the best variety with their field contexts. Existing approaches to generate these recommendations lack scalability and predictivity in marginal production environments. We tested if crowdsourced citizen science can address this challenge, producing empirical data across geographic space that, in aggregate, can characterize varietal climatic responses. We present the results of 12,409 farmer-managed experimental plots of common bean (Phaseolus vulgarisL.) in Nicaragua, durum wheat (Triticum durumDesf.) in Ethiopia, and bread wheat (Triticum aestivumL.) in India. Farmers collaborated as citizen scientists, each ranking the performance of three varieties randomly assigned from a larger set. We show that the approach can register known specific effects of climate variation on varietal performance. The prediction of variety performance from seasonal climatic variables was generalizable across growing seasons. We show that these analyses can improve variety recommendations in four aspects: reduction of climate bias, incorporation of seasonal climate forecasts, risk analysis, and geographic extrapolation. Variety recommendations derived from the citizen science trials led to important differences with previous recommendations.

SUMMARYRapid climatic and socio-economic changes challenge current agricultural R&D capacity. The necessary quantum leap in knowledge generation should build on the innovation capacity of farmers themselves. A novel citizen science methodology, triadic comparisons of technologies or tricot, was implemented in pilot studies in India, East Africa, and Central America. The methodology involves distributing a pool of agricultural technologies in different combinations of three to individual farmers who observe these technologies under farm conditions and compare their performance. Since the combinations of three technologies overlap, statistical methods can piece together the overall performance ranking of the complete pool of technologies. The tricot approach affords wide scaling, as the distribution of trial packages and instruction sessions is relatively easy to execute, farmers do not need to be organized in collaborative groups, and feedback is easy to collect, even by phone. The tricot approach provides interpretable, meaningful results and was widely accepted by farmers. The methodology underwent improvement in data input formats. A number of methodological issues remain: integrating environmental analysis, capturing gender-specific differences, stimulating farmers' motivation, and supporting implementation with an integrated digital platform. Future studies should apply the tricot approach to a wider range of technologies, quantify its potential contribution to climate adaptation, and embed the approach in appropriate institutions and business models, empowering participants and democratizing science.

Although community level seed-saving initiatives have been around for about 30 years, until recently they have received little attention in the scientific literature on climate change adaptation and plant genetic resources. Based on research experiences from various countries, this article argues that community seed banks can enhance the resilience of farmers, in particular of communities and households most affected by climate change. Community seed banks can secure improved access to, and availability of, diverse, locally adapted crops and varieties, and enhance related indigenous knowledge and skills in plant management, including seed selection, treatment, storage, multiplication, and distribution.Bien que les initiatives de conservation des semences au niveau des communautés aient existé depuis environ trente ans, jusqu'à récemment ils ont fait l'objet de peu d'attention de la part de la littérature scientifique sur l'adaptation au changement climatique et les ressources phytogénétiques. Se basant sur les recherches conduites dans plusieurs pays, cet article avance que les banques de semences communautaires peuvent renforcer la résilience des agriculteurs, en particulier ceux vivant dans les communautés et les foyers les plus affectés par le changement climatique. Les banques de semences communautaires peuvent garantir l'amélioration de l'accès à/la disponibilité des cultures et des variétés adaptées au plan local, et renforcer les connaissances et les compétences indigènes en gestion des plantations, y compris la sélection, le traitement, le stockage, la multiplication et la distribution des semences.Aunque las iniciativas comunitarias para conservar semillas existen desde hace casi 30 años, hasta hace poco tiempo dichas iniciativas habían recibido poca atención en investigaciones científicas sobre la adaptación al cambio climático y a los recursos fitogenéticos. Tomando como base investigaciones realizadas en varios países, el presente artículo sostiene que los bancos comunitarios de semillas pueden acentuar la resiliencia de los campesinos, particularmente la de aquellos hogares y comunidades más afectados por el cambio climático. Los bancos comunitarios de semillas pueden mejorar el acceso a cultivos adaptados a ambientes locales y a variedades diversas, así como su disponibilidad. A la vez, enriquecen los conocimientos indígenas, fortaleciendo sus habilidades en la gestión de plantas, lo cual abarca la selección, el tratamiento, el almacenamiento, la multiplicación y la distribución de semillas. ARTICLE HISTORY

The core objectives of the Convention on Biological Diversity and the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA) are the conservation and sustainable use of plant genetic resources. The ITPGRFA links these goals explicitly to farmers' rights. Although farmers' rights have been debated intensely at international level, their effective implementation at national level remains a major challenge. Community seed banks are good examples of effective implementation of those rights, but have received little attention in scientific literature and policy circles. Case studies in this article from Bangladesh, Côte d'Ivoire, India and Zimbabwe illustrate how this knowledge gap can be filled.

Wageningen Centre for Development Innovation supports value creation by strengthening capacities for sustainable development. As the international expertise and capacity building institute of Wageningen University & Research we bring knowledge into action, with the aim to explore the potential of nature to improve the quality of life. With approximately 30 locations, 6,500 members (5,500 fte) of staff and 12,500 students, Wageningen University & Research is a world leader in its domain. An integral way of working, and cooperation between the exact sciences and the technological and social disciplines are key to its approach.