Abstract: In order to demonstrate the feasibility and application prospect of the silage-grain maize double season flexible planting pattern with flexible sowing date of summer maize in North China Plain under the background of the change of water and heat resources and grain demand structure, an experiment was conducted at Yucheng Comprehensive Experimental Station of the Chinese Academy of Sciences from 2020 to 2021, and its annual grain equivalent yield and utilization efficiency of heat and water resources were analyzed. The results showed that: (1) the flexible sowing period of summer maize with high annual heat use efficiency (HUE) of double season maize cropping pattern was from June 1 to June 29, with an average annual HUE of 3.1kg•ha⁻¹·(℃·d)⁻¹. (2) The flexible sowing period of summer maize with high annual water use efficiency (WUE) of double maize cropping pattern was from June 1 to June 15, with an average annual WUE of 2.1kg•m⁻³. (3) Based on the flexible sowing period, which was from June 1 to June 15, the average annual grain equivalent yield was 12886.4kg•ha⁻¹, which was 14.0% lower than the average annual yield of winter wheat-summer maize. Whereas the annual water consumption of double maize cropping pattern decreased by 34.4% and annual water use efficiency increased by 30.9%, compared with the annual average of winter wheat-summer maize. The silage-grain maize double flexible planting pattern can effectively reduce annual crop water consumption, improve annual water use efficiency under the condition of the same yield.

Key words: Silage-grain maize double season flexible planting pattern, Sowing date of summer maize, Water use efficiency, Heat use efficiency