Fluorescence Response of Greening Seedling of Four Tree Species to Low Temperature Stress

Abstract

Fluorescence indexes of Cassia bakeriana, Syzygium hainanense, Ilex rotunda and Phoebe sheareri seedlings were determined under simulated low temperature stress using artificial climate chambers. The results showed that with increasing low temperature time, the minimal initial fluorescence Fo of C. bakeriana fluctuated, S. hainanense and P. sheareri decreased followed by an increase, I. rotunda decreased and then fluctuated; The biggest fluorescent Fm of C. bakeriana and I. rotunda increased followed by a decrease and increased again, S. hainanense continuously decreased; the largest PSII photochemical efficiency Fv/Fm of C. bakeriana and I. rotunda S. hainanense continuously decreased, S. hainanense increased followed by a decrease, whereas P. sheareri decreased followed by an increase; the PSII actual light quantum yield Y(II) and photosynthetic electron transport rate ETR of seedlings of the four tree species decreased; nonâ€photochemical quenching of C. bakeriana and S. hainanense fluctuated, whereas that of I. rotunda and P. sheareri continuously decreased. Two days after lowâ€temperature release, Fo of seedlings of the four tree species decreased, Fm of C. bakeriana, S. hainanense and I. rotunda, and Fv/Fm, Y(II), ETR and NPQ of seedlings of the four tree species increased. The fluorescence parameters of seedlings of the four tree species was evaluated using principal component analysis, indicating that coldâ€resistance ability decreased in the order of C. bakeriana > P. sheareri > I. rotunda > S. hainanense