A study on the suitable sowing date of winter wheat with limited water supply under the background of climate change

Climate change has intensified since the Industrial Revolution, leading to changes in winter wheat and summer maize growth conditions in the central and northern parts of North China Plain. Modifying the sowing date of winter wheat to implement the “two early-two late” technology in this area is important. Based on the interannual variation in meteorological factors during the growing season of winter wheat from 2016 to 2023 at the Luancheng Agro-Ecosystem Experimental Station of the Chinese Academy of Sciences, this experiment studied the suitable sowing date of winter wheat in the context of climate change. Using field-measured data of four winter wheat cultivars for seven growing seasons from 2016 to 2023 with four sowing dates under limited irrigation from 2016 to 2023, the suitable sowing date and necessary heat conditions for winter wheat were determined to achieve a stable yield. The four sowing dates were normal (sowing date 1) and extended by 5−7 days each for delayed sowing dates (sowing date 2, 3, and 4). The results showed that the yield of winter wheat (excluding SY20) decreased after date 2 and that the yield for date 4 was lower than that for the other three sowing dates. Under the current climate conditions, the suitable sowing date was October 12–24. The thermal time before winter and the total thermal time during the whole growing season should reach 350 and 2010 °C·d, respectively. Different sowing dates affect the duration of the different stages of winter wheat through thermal time. With the delay in the sowing date, the durations of sowing—overwintering, overwintering—jointing, joining—anthesis, and anthesis—maturity were shortened, prolonged, prolonged, and shortened, respectively, and the responses to the sowing date of different cultivars were different. Winter wheat sown late was not capable of sufficient tillering before winter and formed the largest population at the jointing stage. The lag in the development process negatively affected the spike number and reduced the duration of reproductive growth, resulting in reduced crop yield. Before anthesis, the biomass production increase rate of winter wheat was synchronized with the dynamic changes in the community. If high temperatures were encountered in late winter and early spring, the gap caused by the slow growth in the early stages of late-sowing winter wheat could be narrowed. The effects of the sowing date on the three yield elements were as follows: spike number decreased, kernels per spike increased, and no statistically significant difference in the 1000-kernel weight. The harvest index of late-sowing winter wheat was higher than that of early-sowing winter wheat. Grain quality decreased with the delay in the sowing date, but differences existed among the cultivars. In conclusion, the outcome of this study that the suitable sowing date should be postponed under the context of climate change provides theoretical support for the decision to implement the “two early-two late” technology in the central and northern parts of North China Plain and reduces the pressure on agricultural development to adapt to climate change.