International Price Transmission in Chinese Grain Futures Markets: Determinants, Channels, and Implications for Food Security

Grain price stability is fundamental to global food security, yet the extent to which major grain futures markets contribute to international price discovery and transmit price signals across borders remains insufficiently understood. This study constructs a measurement–mechanism–pathway framework to analyze the international price transmission dynamics of four grain futures: wheat, rice, corn, and soybean. We apply the Diebold–Yilmaz spillover index, OLS regressions with mediation analysis, and fsQCA. All four crops display predominantly negative net spillover indices, with rice exhibiting the strongest transmission and soybean the weakest. At the domestic level, yield is associated with stronger price transmission through an inventory channel, while the effects of price regulation are asymmetric. Notably, soybean producer subsidies are unexpectedly associated with stronger rather than weaker international price transmission. At the international level, crude oil prices are associated with weaker grain price transmission primarily through the freight cost channel, and speculative capital is associated with reduced transmission capacity through tail-price episodes. Configuration analysis reveals two shared improvement routes, namely capacity building with policy support and risk containment via volatility suppression, together with four commodity-specific pathways. These findings provide systematic evidence and policy insights for mitigating grain price contagion and strengthening food system resilience.