Impact of the eco-efficiency of food production on the water-land-food system coordination in China: A discussion of the moderation effect of environmental regulation.

The coordination of the water-land-food ("WLF") system is an essential guarantee for ecologically sustainable food production. Based on the perspective of symbiosis theory, we explore practical strategies for enhancing WLF system coordination in China. First, we applied the entropy TOPSIS method to measure WLF system coordination. Second, we used the global-Malmquist-Luenberger ("GML") index to calculate the eco-efficiency of food production. Third, we used the panel Tobit model to empirically explore the improvement path of WLF system coordination and test the moderating role of environmental regulation. Our research has led to the following five conclusions: (i) From 2003 to 2019, the coordination level of the WLF system in all regions of China showed a decreasing trend followed by an increasing trend, with the highest in the Northeast (0.380). The eco-efficiency of food production showed an upward trend in general, with the middle and lower reaches of the Yangtze River (2.101) and the northeastern region (1.888) at a higher level nationwide; (ii) The eco-efficiency of food production does effectively promote WLF system coordination, but with a specific time lag; (iii) The regression results of northern China and major grain-producing areas are consistent with the whole sample. However, the eco-efficiency of food production and its lagging term in southern regions and nonmajor grain-producing regions cannot effectively promote WLF system coordination; (iv) According to the quantile regression results, the promotion of eco-efficiency in food production is more pronounced in regions with higher WLF system coordination (at the 50 %-90 % quantile); and (v) Environmental regulation has a positive moderating effect on the ecological efficiency of food production on the coherence of the WLF system. Moreover, the regression results of grouping moderation show that environmental regulations can play a more vital, positive moderating role in the lower regions compared with higher WLF system coordination regions. Our research innovatively explores the influencing factors of WLF System Coordination. Our research also provides a reference for the formulation of food ecological planting strategies and government environmental regulation policies.