Wheat plants exposed to winter warming are more susceptible to low temperature stress in the spring

Winter warming is a main consequence of global climate change, which may influence cold acclimation of winter crops hereby reducing their tolerance to low temperature stress in the spring. In this study, winter wheat plants were exposed to winter warming, i.e., increasing air temperature by 2.89 A degrees C for 35 days (from 7th December 2010 to 11th January 2011), and then subjected to a 5-day low temperature stress, i.e., 8.44 A degrees C lower than the ambient temperature, from 8th to 12th April 2011. Plants grown under ambient temperature during the whole season served as control. Compared with the control plants, spring low temperature stress and the combination of winter warming and spring low temperature stress significantly decreased plant growth. The plants experienced winter warming possessed lower oxygen scavenging capacity due to the decreased activities of SOD, APX and CAT in chloroplasts and mitochondria, resulting in over accumulation of ROS stress. This adversely affected electron transport in PS II (ETo/RC), trapping efficiency (TRo/RC) and PSI acceptor in the photosynthetic apparatus, leading to lower photosynthetic rate during spring low temperature stress. It is concluded that wheat plants experienced warm winter are more susceptible to low temperature stress in the spring.