Effect of the Different Concentrations of S3307 on Photosynthesis and Chlorophyll Fluorescence Parameters of Zinnia elegant Seedling Under High Temperature Stress

In this study,Zinnia elegant plug seedlings with 3—4 leaves were used to analyze assimilation product distribution,photosynthesis,water use efficiency and chlorophyll fluorescence parameters under high temperature stress.The results showed that under high temperature stress,plant height of Zinnia elegant with different concentrations(10,20,30,40 mg/L)of S3307 were reduced and stem diameters were increased,however,dry weight of shoot and root,root-shoal ratio in dry weight were higher than those of the control,and photosynthetic rate and water use efficiency of those treatments were increased as well.The treatment of S3307 significantly slowed down the inhibition of high temperature stress on photosynthetic system Ⅱof seedlings,alleviated the decrease of maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency under light(ΦPSⅡ),photochemical quench(qP)and the increase of no photochemical quench(NPQ) and prevented the damage of high temperature on photosynthetic apparatus.Among them,the treatment effect of 30 mg/L S3307 is the best.