Abstract: The effects of shade degrees 100% , 50% and 25% of full sunlight on the growth and photosynthetic characteristics of poinsettia ‘Prestige’ and ‘Red Velvet’were examined. The results indicated that poinsettia was a sun plant with high light-saturation point and low light-compensation point. But the shade tolerance of different cultivars was different. Under shade conditions, the contents of chlorophyll increased and leaf color greener, but their net photosynthetic rates, the contents of soluble sugars and proteins in leavesdecreased and the growth of lateral shoots were inhibited, resulting in decreasing of flower diameters, red bract areas, contents of anthocyanidin in braces finally.

Key words: Poinsettia ( Euphorbia pulcherrima Willd), Shade, Photosynthetic characteristics, Ornamental value