The roles of agri-food tech start-up ecosystems in strategic niche management for food system transitions

• Analyses agri-food tech start-ups as sustainability niches using SNM. • Shows aligned sustainability visions but fragmented expectations, networks and learning. • Explains how start-up ecosystems construct and govern protected spaces. • Demonstrates how ecosystem protection systematically favours some niche trajectories. • Reveals hybrid niche empowerment: technological stretch with institutional fit. Agri-food tech start-ups have gained prominence in food system transformation debates, yet while transitions research has extensively examined grassroots innovations focused on agroecology, these technology-driven niches and the ecosystem configurations shaping their transformative trajectories have so far received limited analytical attention. Drawing on Strategic Niche Management theory, this study examines whether and how agri-food tech start-ups develop as niches for sustainability transition in terms of niche-internal processes and how start-up ecosystems influence their development through niche protection, using the Chilean agri-food tech start-up ecosystem as a case. Our findings show strong symbolic alignment across the Chilean agri-food tech niche with Agriculture 4.0, Food 4.0 and other sectoral imaginaries of sustainability transitions across agri-food tech ventures. However, there is also persistent operational fragmentation in the niche, characterised by weak inter-venture coordination, transactional rather than collaborative networks, and duplicated rather than cumulative learning. Start-up ecosystem actors provide essential niche shielding and nurturing through staged financing and infrastructure support, but simultaneously embed what we call ‘directional filtering’. This directional filtering happens through capital-structure mismatches favouring scalable models, corporate gatekeeping, policy inconsistencies, and geographic concentration that favour certain innovations while marginalising others. In terms of niche empowerment, most ventures display hybrid empowerment strategies combining technologically ambitious innovations that challenge the status quo with institutional conformism, a configuration shaped by directional filtering of the start-up ecosystem rather than deliberate strategic choice. These findings reveal directional filtering and niche fragmentation to be mutually constitutive, as ecosystem support tends to favour certain ventures while undermining collective coordination and shared niche development. To enable more transformative agri-food tech start-up niches, this suggests a need for more transformative or mission-oriented start-up ecosystems, requiring patient capital, binding sustainability commitments, and multi-stakeholder governance.