Abstract: The effects of drought, CO₂ concentration and temperature increasing on development period, photosynthesis rate (P_n), evapotranspiration (ET), and water use efficiency of spring wheat were investigated. The results showed that elevated CO₂ concentration (550, 700μmol·mol^-1 ) could lengthen heading ripening period, but high temperature (average diurnal temperature increase 4.8℃), which made heading ripening period shorten and speeded the seedling under treatment of both high CO₂ concentration and high temperature, affected growing period more than high CO₂ concentration. The combined effects of elevated CO₂ concentration and temperature enhanced P_n, stomatal resistance (r), leaf water use efficiency (WUEl), and whole canopy water use efficiency (WUE), while transpiration rate (E) were not significantly affected. The effects on ETdepended on soil moisture. High CO₂ concentration and high temperature enhanced ETunder high (75%～85% field water capacity)and middle(55%～65% field water capacity)soil moisture, but decrease ETunder low soil moisture (35%～45% field water capacity).

Key words: Climate changes, Spring wheat, Photosynthesis rate, Evapotranspiration, Water use efficiency, net primary productivity, carbon stock, mangrove, biomass, litterfall.