| Since the industrial revolution,human activities have led to massive emissions of greenhouse gases such as CO2,causing global warming and extreme drought in some areas.Lespedeza davurica is an forage plant with strong drought tolerance in northern China,and it’s worth discussing the adaptability under the influence of elevated CO2 concentration and drought.In this study,the experiment was conducted to study the effects of doubled CO2（400 μmol/mol;800 μmol/mol）and drought stress on the 2,4,6,8,10,12,14,16 days on the growth characteristics,photosynthetic characteristics,chlorophyll fluorescence characteristics and antioxidant properties of ‘Jinnong NO.1’ Lespedeza davurica seedlings.The results are as follows:（1）Doubled CO2 alleviated the inhibitory effect of drought stress on the above ground growth and promoted the underground growth of Lespedeza davurica seedlings;（2）Doubled CO2 improved the contents of Chl a,Chl b and carotenoids of Lespedeza davurica seedlings leaves under drought stress,increased Pn,Ci and WUE of seedlings,decreased Tr and Gs of seedlings;（3）Doubled CO2 increased the Fv/Fm,Y（II）,Fv’/Fm’,q L,NPQ and ETR of Lespedeza davurica seedlings leaves under drought stress;（4）Doubled CO2 increased the SOD and POD activities of Lespedeza davurica seedlings leaves under drought stress,increased the content of LRWC and Pro,inhibited the synthesis of MDA,and decreased the relative conductivity of seedlings leaves.In summary,doubled CO2 concentration alleviated the photosynthesis mechanism of Lespedeza davurica seedling under drought stress,promoted the synthesis of photosynthetic pigments,increased the antioxidant enzyme activity of seedlings,and delayed the onset of membrane lipid peroxidation,improved the tolerance of Lespedeza davurica seedlings under drought stress.It could provide a theoretical basis for breeding Lespedeza davurica varieties with adaptation to future climate change and high drought resistance in actual production. |
