Response of photosynthetic characteristics to water stress of maize leaf in seeding
The response of photosynthetic characteristics in two different drought-resistant maize varieties(XY335 and SD902)was studied by measuring gas-exchange and modulated chlorophyll fluorescence under 4 different water stresses in pots.The result shows that,except C_i and qN increasing,other parameters decreased when increasing water-stress.All parameters of XY335showed little change than SD902.The maximum difference of gas-exchange parameters in light drought between two maize hybrids,However,chlorophyll fluorescence parameters show it in serious drought.Fitted results from photo-repose curves of P_n and rETR showed that water stress has induced photosynthetic potential and light use efficiency,as well as promote photoinhibition,all fitted parameters of XY335 showed little change than SD902.The fitted parameters from photo-repose curves of P_n show the most obvious variance in light drought,the fitted parameters from photo-repose curves of rETR show it in serious drought between two maize hybrids.Summing up and draws a conclusion,increased sensitivity of maize leaves to highlight under water stress.Main cause restraining factors of photosynthesis was that,Photo-system can be overlapping injury by drought and photoinhibition,which Injury will be further intensified as water-stress exacerbated and drought resistance reduced of maize varieties.Maize seedling should make-up water in time to avoid the overlapping injury by drought and photoinhibition under strong light in arid area.
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