Effects of Day and Night Temperature on Rice Photosynthesis
Kristian Johnson, Sabine Stürz, Marc Schmierer, Folkard Asch
University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Germany
It has been shown that the yield of rice (Oryza sativa) decreases in response to higher night temperatures. Projected temperature increases due to climate change are expected to be more pronounced at night. As the primary staple for more than half of the world's population, a decrease in rice yield could pose a serious threat to food security. However, the physiological response of rice to night temperature is not yet fully understood. Studies indicate both positive and negative effects of high night temperatures on CO2 assimilation and growth in rice. It has also been shown that the physiology of rice during the day is also affected, as warmer nights lead to higher leaf conductance and net assimilation rates during the day. It is unclear if the day response is part of a mechanism to compensate for depleted carbohydrate pools within the leaves from night-time respiratory CO2 losses. A day-time increase in net assimilation, comprised of assimilation, day respiration, and photorespiration, implies changes in the photosynthetic complex to either reduce CO2 releasing processes or an increase in assimilation.
Keywords: Climate change, mesophyllic conductance, night temperature, photosynthesis, photorespiration, respiration, rice
Contact Address: Folkard Asch, University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Garbenstr. 13, 70599 Stuttgart, Germany, e-mail: fauni-hohenheim.de