Effect of S-deficiency stress on chlorophyll fluorescence kinetics of rice leaves

Effect of S-deficiency on the characteristics of rice leaf photosynthesis was studied by using water culture.The results showed that under the S-deficiency condition,net photosynthetic rate(Pn),initial fluorescence value(Fo),ratio of the variable to maximum fluorescence(Fv/ Fm),actual photochemical efficiency(ФPSⅡ)and electron transport rate(ETR)in the leaves decreased significantly,non-photochemical quenching coefficient(NPQ)increased,and capability of photosynthesis decreased.Either destruction of PSⅡreaction center or reversible activity loss did not decrease the PSⅡactivity of the leaf.Increase of NPQ caused the decrease of Fo in S-deficient rice,and this might be a mechanism for the rice to adapt itself under adversity of S-deficiency.