Effect of drought stress on chlorophyll fluorescence of maize leaves at seedling

The response of photosynthetic characteristics in two maize varieties(ZD958 and SD902) with different drought-resistance was studied by measuring chlorophyll fluorescence parameters under three different water stress in pots.The results showed that with the increase of drought stress on the two maize varieties,the chlorophyll content,effective quantum yield(φPSⅡ),electron transfer rate(ETR) and photochemical quenching(qP) decreased,maximum electron transmission rate(ETRm) and quantum efficiency reduced at different degrees,while the non-photochemical quenching(qN) of chlorophyll fluorescence increased and maximum efficiency of PSⅡ(Fv/Fm) changed little.All these indicated that mild water stress did not cause permanent damage to photosynthetic apparatus,but kept it stable through reducing light energy utilization and increasing heat dissipation.However,the amplitude of each parameter in ZD958 was less than that in SD902.These suggested that high efficiency of electron transfer and light transform of ZD958 may be one of the physiological reasons for its drought tolerance and high yield.