Fields experiments in North China show no decrease in winter wheat yields with night temperature increased by 2.0–2.5°C

The trends of daily maximum and minimum temperature in global warming indicated that the daily minimum temperature ( T min ) has risen more than twice as fast as the daily maximum temperature ( T max ) during the 20th century. Most researchers have focused on how the crops respond to daily mean temperature, whereas few controlled experiments were carried out to investigate how the crops respond to the T min rise. In particular, no experiment research has reported on how crops respond to the higher night temperature, which was the main trend in the climate warming. Taking winter wheat as the test crop, we investigated how the winter wheat growth and yields responded to the higher night temperature. In the field experiments, infrared heaters were used to increase higher night temperature (HNT) by about 2.5°C in contrast to the normal night temperature (CK) in two whole growth durations of winter wheat in 2008–2009 and 2009–2010 in North China. The results indicated that, compared to the CK treatment, winter wheat yield did not decline in HNT treatment, which increased temperatures by 2.0–2.5°C in both Warmer year (WY) and Colder year (CY). Furthermore, winter wheat yield in CY increased significantly in HNT treatment. HNT treatment in CY could significantly promote tillering and increase the effective panicles, which increased grain yield significantly (by more than 30% compared with CK). HNT treatment in CY contributed to an increase in the effective panicles and Kernels significantly, although making a significant reduction in 1000-grain weight, but did not lead to the yield decline. Under the HNT treatment, the whole growth duration of the winter wheat was shortened and the phenological dates were earlier except for the beginning of overwintering; the beginnings of the overwintering phase were postponed substantially and the ends of the overwintering phase were ahead of date compared to CK, which shortened the duration of overwintering considerably. We draw on our own studies to show examples of higher night temperature impact on winter wheat in a relatively cold year and relatively warm year in North China. Our results refer to winter wheat in North China, not all main winter wheat producing regions, in Huang-Huai and Southwest of China. Some uncertainties of our predictions derive from fast progress in crop breeding, the variability of climate, and the role of adaptive actions in the future. As expected, the adaptation measures should be considered to c