Abstract: The drought characteristics and trend of spring maize in Songnen Plain were studied by using the meteorological data from 2001 to 2020 and the crop water deficit index (CWDI). The results showed that during the whole growth period of spring maize, the variation trend of precipitation and water demand in Songnen Plain was similar, both showed a trend of first rising and then decreasing, and peaked in mid-late July. CWDI showed a trend of decreasing first and then rising, and reached the lowest value in the mid-late July. Drought was more severe in the early and late stages of growth. A trend of drying occurred in whole growth stage, seeding-emerging stage, and heading-milking stage, while a trend of wetting occurred in emerging-heading stage and milking-ripening stage, with such trends being significant except for the emerging-jointing stage, and the drought gradually shifted to the late stage of growth. In each growth stage, the influence scope of light drought was predominant, followed by moderate drought, severe drought, and extreme drought. Spatially, drought occurrence frequency was generally higher in the west and lower in the east, and higher in the north and lower in the south. It is necessary to strengthen the monitoring and early warning of drought in the future and increase the input of drought disaster prevention, which can provide strong guarantee for stable yield and supply of maize.

Key words: crop water deficit index, drought, spring maize, Songnen Plain