OBJECTIVETo investigate the effect of light intensity on growth and photosynthetic of Chrysanthemum morifolium.

METHODThe growth characteristics of C. morifolium were measured under different treatments (100%, 80%, 60%, 40% and 20% of full sunlight). The photosynthetic characteristics and chlorophyll fluorescence parameters of leaves under different light intensity were determined by a LI-6400 photosynthesis system and a PAM-2100 chlorophyll fluorescence system.

RESULTWith the reduction of irradiance, the diameter of the stem reduced, plant height, leaf length, leaf width and length/width raised, assimilation product increased; Content of photosynthetic pigment increased between light intensity 100%-40% reduced under 20% treatment, chlorophyll a/b decreased. Light compensation point (LCP), apparent quantum yield (AQY) increased first and reduced later, photosynthesis rate (P(n)), stomatal conductance (G(s)), intercellular CO2 concentration (C(i)) and transpiration rate (T(r)) decreased, stomatal limitation value (L(s)) rose. Chlorophyll fluorescence parameters F(v)/F(m) increased, phiPS II, F(v)'/F(m)', ETR and qP increased between irradiance 100%-60%, NPQ decreased, such as phiPS II decreased and NPQ increased when irradiance was lower than 40%.

CONCLUSIONWeak light condition was unfavorable to the growth of C. morifolium and the light conditions of culture should be control between 80%-60% of full sunlight.