Freezing Injury of Winter Wheat in Northern China and Delaying Sowing Date to Adapt

Abstract

Under the background of global warming, whether freezing injury is still the main meteorological disaster in northern winter wheat growing region of China becomes uncertain, and whether delaying sowing date is an effective measurement to adapt to climate change becomes an urgent scientific problem to solve. It is found that the correlation coefficient between winter freezing injury index and winter wheat yield reduction rate is 0.62 in the northern winter wheat region from 1981 to 2000, which indicates that winter freezing injury is one of the main disasters before the year of 2000. However, this correlation becomes very low after the year of 2000, indicating that winter freezing injury is no longer the main factor for yield reduction of winter wheat. Experiments are carried out at Taian and Xianyang stations, showing that the accumulated temperature before winter and the accumulated temperature of the whole growth season of winter wheat are significantly reduced. The plant height, total aboveground dry weight and leaf area index will decrease when sowing date of winter wheat is delayed for 10 days and 20 days. Furthermore, the delay of sowing date has an adverse impact on the yield structure, the effective panicles and grains per panicle are decreased by 5% and 10.2% respectively when the sowing date of winter wheat is delayed for 10 days from 2018 to 2021 at Taian Station, and they are decreased by 17.2% and 11.9% respectively when the sowing date is delayed for 10 days at Xianyang Station. Overall, the average yield of winter wheat is reduced by 22% and 40% when sowing dates are delayed for 10 days and 20 days respectively, which indicates that the delayed sowing date of winter wheat have no positive effects. The possible cause is that the local winter wheat varieties have changed at Xianyang and Taian, and farmers have appropriately adjusted the sowing date according to experience. The current winter wheat sowing date and the main winter wheat varieties have adapted to local climate change.

Keywords

• freezing injury
• measurements to adapt to climate change
• yield