Effect Of Elevated [CO₂] On Growth And Yield Of Winter Wheat

With the increasing concentrations of CO2 and other greenhouse gases, the global climate has been changed. As the substrate of plant photosynthesis, CO2 can affect plants growth and development directly or indirectly. Winter wheat is the second major grain crop in China. Under the climate changing background of elevated [CO2],the yield, physiological and ecological index of winter wheat may be changed,and that is an urgent problem that we need to solve. The study used the FACE test platform of Chinese Academy of Agricultural Sciences in Changping, Beijing. We selected two varieties of winter wheat, SLM and SH8675, and repeated three times to research the effect of elevated [CO2] on physiological and ecological index. In the response experiment we respectively studied several aspects such as photosynthetic physiological indexes, morphological indexes, the production and distribution of the dry of matter above ground, the yield and the yield components. Main conclusions are drawn as follows:(1) Elevated [CO2] increased the net photosynthetic rate and water use efficiency but declined slightly the stomatal conductance and transpiration rate.(2) The chlorophyll fluorescence kinetics parameters on winter wheat towards high CO2 concentration were not significantly changed, but there were differences between the varieties and growth periods.(3) After the CO2 concentration was elevated, the dry matter of above ground in SH8675 was increased 3.39% but SLM was decreased 9% in 2012; the dry matter of aboveground in SH8675 was increased 17.38% and SLM was increased 46.07% in 2013.(4) Under the condition of FACE, the proportions of leaves and stems dry matter of above ground in SH8675 was decreased, but the proportion of ears dry matter of above ground in SH8675 was increased 2.54% in 2012; the proportions of leaves and stems dry matter of above ground in SH8675 was decreased, but the proportion of ears dry matter of above ground in SH8675 was increased 3.02% in 2013. The proportion of leaves dry matter of above ground in SLM was decreased 15.63%, but the proportions of stems and ears dry matter of above ground in SLM was respectively increased 3.25% and 1.73% in 2012; the proportion of leaves dry matter of above ground in SLM was increased 84.24%, but the proportions of stems and ears dry matter of above ground in SLM was respectively decreased 19.94% and 20.01% in 2013.(5) The elevated [CO2] increased the plant height of SLM and SH8675 by 2.67% and 10.60%, respectively. increased the ear length of SLM and SH8675 by 6.90% and 0.24%, respectively, increased the total spikelets number of SLM and SH8675 by 6.91% and 1.45%, and increased the effective spikelets number of SLM and SH8675 by 10.17% and 1.40%, respectively.(6) After the CO2 concentration was elevated, the yield of SLM was decreased 12.1% in 2012 but was increased 7.1% in 2013; the yield in SH8675 in 2012 and 2013 was increased by 7.5% and 12.4%, respectively. The response of yield towards high CO2 concentration was not significant.