Abstract: The two-year-old southern highbush blueberry cultivar‘Emerald’were used to study the effect of LED supplemental light in greenhouse. Selecting the natural light as the control，we evaluated the plant growth situation，photosynthesis，carbon and nitrogen metabolism，the expression of flowering control genes，flowering rate and fruit quality under LED supplemental light of the red/blue light（3︰1 and 6︰1），ultraviolet A（UVA）. The results showed the red/blue light treatment was beneficial for the vigorous vegetative growth of‘Emerald’，which could increase the plant height，the length and diameter of annual branches. Meanwhile，the leaf chlorophyll relative content，specific leaf weight and net photosynthetic rate were significantly improved by red/blue（6︰1）treatment. In addition，the expression of flowering gene FT and flowering rate were remarkably higher than those of the control，indicating the red/blue light induced flowering earlier. The nitrogen contents of leaves，the flowering rate and the expression of FT gene under UVA light were higher than those of the control. Moreover，the red/blue（3︰1）treatment raised the fruit quality of‘Emerald’，characterized by a heavier fruit weight，the increase in the transverse and longitudinal diameter，the content of soluble solids，soluble sugar，anthocyanin and the sugar acid ratio. In summary，the application of different LED supplemental light can promote the growth and development of the blueberry‘Emerald’，because the red/blue（6︰1）treatment works better on the vegetative growth while the red/blue（3︰1）treatment improves because the fruit quality. Although the UVA treatment can change plant morphology and accelerate flowering，its effect on fruit quality was slightly weaker than that of the red/blue light treatment.

Key words: Vaccinium corymbosum, LED complementary light combination, growth potential, photosynthesis, flowering rate, fruit quality