Effect of Low Light Density on Chlorophyll Fluorescence Parameters of Tomato Seedling Function Leaves

The chlorophyll fluorescence parameters of seedling function leaves in 4tomato strains were investigated under low light density environments.The results showed that the different changing of the chlorophyll fluorescence parameters occurred in 4tomato stains under low light density.Except the initial fluorescence(Fo)and maximal fluorescence (Fm)were lower in stains 1,2and higher in stains 3,4under low light density environments,the PSⅡmaximal photochemical efficiency(Fv/Fm)and latent photochemical activity(Fv/Fo)were higher than control light density,it meant that the photochemical potentiality of PSⅡreaction centers was enhanced.But the PSⅡreal photochemical efficiency (ΦPSⅡ)and photochemical quenching coefficient(qP)decreased,it perhaps was the one of the reasons that the photosynthesis decreased in low light density,and the decreased extent was lower in stains 1,2than that in stains 3,4.It was tiny that the effect of low light density on nonphotochemical quenching coefficient(qN)in 4tomato stains.