| Water deficit and low temperature restricted crop production in the arid regions of northwest China. Film mulching has been widely used as it could increase temperature and preserve soil moisture, improve crop growth and increase crop yield. However, the thermal effect of film mulching with different color and its effect on growth and yield of winter wheat is still unclear. Therefore, a two-year field experiment was conducted in Yangling, Shaanxi Province from October 2021 to June 2022 (normal season) and October 2022 to June 2023 (wet season). Three treatments, transparent film mulching (WF), black film mulching (BF) and no mulching (CK), were set up to study the effect of film mulching with different color on net radiation, soil heat flux, soil temperature, leaf area index, aboveground dry matter mass, yield and water use efficiency of winter wheat. The results suggested that the cumulative net radiation and cumulative soil heat flux were minimum in treatment of WF. The cumulative canopy net radiation under WF was decreased by 4.9%~5.4% compared to BF, and there was no significant difference compared to CK. The cumulative soil heat flux under WF was decreased by 16.5%~104.1% compared to BF and 99.2%~122.7% compared to CK. Film mulching increased the soil temperature at 5 cm and 10 cm depths of winter wheat at seedling and overwintering stages, and WF treatment decreased the soil temperature at 20 and 25 cm after regreening stage. Film mulching improved the leaf area index and aboveground dry matter. The evapotranspiration of film mulching in 2021—2022 was less than that of non-mulching treatment, and the evapotranspiration of WF treatment was 4.4% significantly lower than that of BF treatment, while filming mulching significantly increased the evapotranspiration of winter wheat in 2022—2023. Compared with CK, the yield and water use efficiency of film mulching treatment increased by 10.3% and 8.9%, respectively, while the water use efficiency of WF treatment was 5.4% significantly greater than that of BF treatment in 2021—2022. Therefore, film mulching could improve the thermal environmental for winter wheat, promote the growth of winter wheat, and increase the yield and water use efficiency. The evapotranspiration of film mulching was decreased in normal season and increased in wet season, and the effect of transparent film mulching on improving water use efficacy and reducing evapotranspiration in normal season is better than that of black film mulching. The results of present study would have certain reference value and practical significance for the high yield and efficient utilization of water and heat in the dry farmland in northwest China. |