Suitable sowing date for stable and high yield of summer maize in the northern region of Huang-Huai-Hai, China

Extreme weather has posed a great threat to the production safety of corn under global warming, such as seriously agrometeorological disasters. The sowing date can be adjusted in the crop growth period against the climate resources. In this study, a sowing date experiment was carried out in Wuqiao County, Hebei Province of China in 2017-2020. Five sowing dates were set as June 5, 10, 15, 20 and 25. Two varieties of summer maize, Zhengdan958 (ZD958) and Denghai605 (DH605), were selected in the northern region of Huang-Huai-Hai (Beijing, Tianjin, and Hebei Province). The experimental observation included the growth stage (emergence, elongation, big flare, tasseling, silking, flowering, and mature stage), and the yield of summer maize. The historical meteorological data was utilized at Wuqiao County and 16 meteorological stations. The suitable sowing date was determined for the high and stable yield of summer maize, according to the climate resources, the main agrometeorological disasters, and the yield during the growth period. The results were obtained as follows. 1) The growth stage of summer maize was gradually advanced, and the duration of the growth period was significantly shortened, with the delay of the sowing date, where the total active accumulated temperature and total radiation during the growth period decreased, while the precipitation at the flowering stage increased gradually. There was no significant difference in the active accumulated temperature between the years of the same sowing date, but the large differences in the solar radiation and precipitation, where the maximum inter-annual difference was 336 MJ/m2 and 255 mm, respectively. The precipitation distribution during the growth period of summer maize was depended mainly on the sowing date and year type. 2) The occurrence frequency of heat damage at the flowering stage was lower than that of the continuous rain, indicating an increasing trend in the recent decade. The occurrence frequency of the heat damage and continuous rain on June 15 was significantly lower than that on the other sowing dates (P<0.05), which were 0.8% and 23.3%, respectively. 3) The yield of summer maize was higher on the sowing date of June 10 and 15, where there was a significant quadratic correlation with the active accumulated temperature ≥15 ℃ after flowering (P<0.05). The ZD958 and DH605 reached the maximum yield, when the active accumulated temperatures ≥15 ℃ after flowering were around 1 550 ℃·d (the sowing date of June 10) and 1 480 ℃·d (the sowing date of June 15), respectively. Consequently, June 15 was the suitable sowing date for the summer maize in the study area. The finding can provide a strong reference for the sowing date adjustment of crops in response to climate change, particularly for the stable and high yield of summer maize.