C. N. DENG1,2, G. X. ZHANG1, X. L. PAN3 and K. Y. ZHAO1
1 Chinese Academy of Sciences, Northeast Institute of Geography and Agroecology Key Laboratory of Wetland Ecology and Environment, Changchun, 130012, P. R. China
2 Graduate University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
3 Chinese Academy of Science, Xinjiang Institute of Ecology and Geography, Key Lab. of Biogeography and Bioresource in Arid Land, Urumqi, 830011. P.R. China
DENG, C. N., G. X. ZHANG, X. L. PAN and K. Y. ZHAO, 2010. Chlorophyll fluorescence and gas exchange responses of maize seedlings to saline-alkaline stress. Bulg. J. Agric. Sci., 16: 49-58
Responses of photosynthesis rate, stomatal conductance, chlorophyll fluorescence characteristics and chlorophyll content of maize (Zea mays L.) seedlings under combined salinity-alkalinity stress were examined. Investigation revealed that the net photosynthesis rate (Pn) and stomatal conductance (gs) decreased rapidly with increasing of salinity-alkalinity stress. The intercellular CO2 concentration (Ci) decreased at low salinity-alkalinity and increased at high salinity-alkalinity. The maximal efficiency of photosystem II (PSII) photochemistry (FV/FM) decreased only at high salinity-alkalinity. The comprehensive photosynthesis performance index (PIABS) gradually decreased with increasing of salinity-alkalinity concentration. The JIP test showed that the electric transfer of donor side and acceptor side of PSII in maize seedlings were inhibited by high salinity-alkalinity stress. Stomatal limitation is the main reason of decreased photosynthesis rate at low salinity-alkalinity, and non-stomatal limitation, i.e. decreased photosynthesis activity in PSII plays an important role in decreased photosynthesis rate at high salinity-alkalinity.