Effects of prolonged weak light duration on photosynthesis and growth of greenhouse tobacco seedlings

Effects of prolonged weak light duration on photosynthesis and growth of greenhouse tobacco seedlings were studied to provide useful references for the improvement of tobacco seedling management.Tobacco seedlings of flue-cured tobacco K326 were irradiated by artificial light source with intensity of 70 μmol ·m-2· s-1 for 4 hours daily after sunset starting from 6 leaf stage to seedling establishment.Results showed no change for light saturation point(LSP) and maximum net photosynthetic rate(Pn max) after prolonging light duration by using weak light.However,light compensation point(LCP) decreased,Pn under weak light and apparent quantum yield(AQY) increased.Content of chlorophyll a and chlorophyll b increased while the value of chlorophyll a/b decreased.Prolonging light duration by using weak light can enhance daily photosynthesis and photosynthetic production capacity,promote seedlings growth and hence improve quality.