Effects of increased day and night temperature with supplemental infrared heating on winter wheat growth in North China

The main future challenge is to feed 9 billion people under a changed climate, and the projected increase in global temperature will affect, negatively or positively, future wheat production depending on the geographical location. Temperature is a key factor in crop growth, development and yield. Global temperatures are rising asymmetrically with the daily minimum temperature rising faster than the daily maximum temperature. The objectives of this study are to evaluate wheat biomass growth, development, yield and harvest index under whole day and night time temperatures increased by 2.5°C in field conditions. The field experiment was carried out during three growing seasons (2008/09, 2009/10, and 2010/11) in Hebei Province, which is the main wheat region of the North China Plain. The experiment was carried out using a warming system with infrared radiation lamps suspended 2.3m above the ground which increased the mean air temperature by 2.0–2.5°C . The treatments were: (1) ambient control (CK: not warmed), (2) higher night temperature (HNT: warmed from 19:00 to 7:00), and (3) higher day–night temperature (HDNT: warmed from 9:00 to 17:00 and 19:00 to 7:00). Each treatment was replicated four times for a total of 12 plots (2×4m2 each) in a randomized complete block design for the growing season 2009/10 and 2010/11 and 5 times in 2008/09. Results of this study, showed that overall wheat biomass increased by 30% and yield by 20% under heating conditions with the highest relative increase for the cold year (2009/10). Grain yield under control treatments, for the cold year, decreased by 37% because the number of days of minimum temperature below 0°C increased by 14 days. Overall, the different warming timing (night-time only versus day–night) did not cause any significant difference in yield and biomass increase. However, as an overall pattern, warming increased aboveground biomass, grain yield, plant height and panicle numbers, but decreased harvest index. In conclusion, wheat growth and yield were significantly increased by artificial warming indicating that a warming in such area of China has potential benefits to current wheat cultivars. Higher temperatures changed the ratio of beginning/length of overwintering causing a significant change in stem numbers.