Water footprint of rain-fed maize in different growth stages and associated climatic driving forces in Northeast China

Rain-fed crops are a major crop type, and their water use is extremely vulnerable to climate change. Studying the water requirement characteristics of rain-fed crops in different growth stages and associated climatic driving factors is of great significance for sustainable crop production. The water footprint (WF) of crops can comprehensively reflect the type and quantity of water consumption during the crop growth period. Previous studies have focused on quantifying the crop WF throughout the growth period, and less attention has been given to quantifying the crop WF in different growth stages. This study quantified the WFs of rain-fed maize and associated climatic driving factors in five growth stages from 1996 to 2018 in Northeast China. The results show that (1) the WF of rain-fed maize in each growth stage showed distinct differences. The highest WF occurred in the tasseling-milky growth stage, whereas the lowest WF occurred in the sowing-emergence growth stage. (2) The variation trends of maize WF in different growth stages were heterogeneous across Northeast China. The declining trends were mainly distributed in the southwest, while increasing trends were mainly distributed in the east in most growth stages. (3) Sunshine hours and temperature had a greater impact on the maize WF in most growth stages. The impacts of other climatic factors on the WF of rain-fed maize differed among different growth stages. Precipitation contributed much more to the variation in maize WF in early growth stages, relative humidity had the greatest impact on the WF of maize in the jointing-tasseling growth stage, and wind speed played a major role in the variation in the maize WF at the milky-mature growth stage. Management measures should be adjusted to alleviate the impact of climatic conditions on crop water consumption in different growth stages according to the results.