Increased atmospheric CO2 enhances heat stress at anthesis in rice not by increased air temperature, but by reduced transpirational cooling through reduced transpiration. Increased CO2 changes carbon and nitrogen dynamics in rice plants and may increase yield potential. But acquiring high yield need better nitrogen application. Our team are researching traits concerning heat stress (flower opening time, anther dehiscence, and pollination and relation between spikelet density and nitrogen under incresed atmospheric CO2.