Abstract: Aims Revealing the regional variation of functional traits and adaptation strategies of eurybiont is of great significance for predicting the adaptation potential of plants under climate change. Methods Here, Setaria viridis was studied with 18 water-carbon related functional traits of stem and leaf organs measured and 9 study sites were selected along the precipitation gradient from southeast to northwest China. The methods of trait network and principal component analysis were used to quantify the regional differentiation of traits, and to clarify their habitat adaptation strategies. Important findings The results showed that: (1) In humid regions, Setaria viridis exhibited the largest vessel diameter and specific leaf mass; in the semiarid/humid region, Setaria viridis exhibited the highest maximum net photosynthetic rate per unit leaf area, anatomical maximum stomatal conductance and stomatal area fraction; in arid regions, Setaria viridis exhibited the highest thickness-to-span ratio of vessel and maximum net photosynthetic rate per unit leaf mass. These various reflected the Setaria viridis’ adaptation strategies in different regions. (2) With the decrease of precipitation, the correlation between traits decreased, the connectivity of the network decreased, and the complexity increased. The proportion of positive correlation between traits of the network reached the maximum in the semiarid/humid regions, showing the best cooperative relationship between plant traits, which may be related to the balanced allocation of water and light resources in this region. (3) The results of the trait network of 9 sites indicating that the adaptation of Setaria viridis along the precipitation gradient was mainly regulated by stomatal traits. This study has great significance for predicting the potential mechanisms of plant’/vegetation’ adaptation under the background of climate change.

Key words: plant functional traits, trait variation, adaptive strategy, eurybiont, Setaria viridis, precipitation gradient