[Effects of osmotic stress on chlorophyll fluorescence parameters of wheat seedling]

By using chlorophyll fluorescence kinetics technology, this paper determined the chlorophyll fluorescence parameters Fv/Fm, phiPSII, qP, qNP, ETR of winter wheat seedling under simulated osmotic stress. The results showed that with the increase of osmotic stress, Fv/Fm and Fv/Fo had the trend of decrease-increase-decrease, indicating that photoinhibition did not happen at the first stage of osmotic stress, but the followed increase of Fv/Fm resulted in the photoinhibition and the decrease of phiPSII and ETR. During the course of osmotic stress, qP and qNP decreased firstly and then increased, which was helpful to enhance the open ratio of PSII reaction center, and made more photosynthetic energy use the photosynthetic electron transport to enhance the electron transport capacity. Meanwhile, the increase of non-photochemical quenching coefficient could be helpful to dissipate excess light energy, which protected the photosynthetic tissue, and mitigated the effect of environment on photosynthesis. All the results indicated that wheat seedling had its protection mechanism. Between the two test winter wheat varieties, Changwu 134 had a higher drought-resistance capacity than Shan 253.