Abstract: The shoot growth and the pigment content, net photosynthetic rate, transp iration rate and
chlorophyll fluorescence of leaf under different shading treatments (0% , 15% , 35% and 50% ) were investi
gated in david maple seeding. The results showed that the p igment content, net photosynthetic rate, minimal
fluorescence ( Fo ) , conversion efficiency of p rimary light energy ( Fv/Fm ) of PS Ⅱ and photochemical
quenching coefficient ( qP) were enhanced, but the non-photochemical quenching coefficient ( qN) was de
creased as shading increased. The diurnal variation curve of net photosynthetic rate had two peaks under 0%
and 15% shading treatments, while there was only one peak under 35% and 50% shading treatments. The di
urnal variations of Fv/Fm showed increase-decrease-increase curve under 0% and 15% shading treatments,
and kep tstable in 35% and 50% shading treatments. It is concluded that 50% shading suitable for the growth
of david maple seedlings.

Key words: David maple, Shading, Pigment, Photosynthesis, Chlorophyll fluorescence