Using the tobacco variety ‘Yunyan 87’ as experimental material and natural lighting for control,the effects of supplemental lighting on leaf growth,chlorophyll content,photosynthesis,chlorophyll fluorescence,and light response curves in tobacco plants was investigated by additional night artificial lighting for 1,2 and 3 h in this study.The results showed that,as compared with the natural lighting,the treatments with supplemental lighting for 2 h obviously promoted leaf length and width,and plant height,the treatments for 1 h and 3 h showed insignificant effect.These supplemental lighting treatments from 1 to 3 h remarkably decreased specific leaf area (SLA) and increased contents of chlorophyll a,b,chlorophyll a+b and carotenoids,and these changes for 1 h and 3 h treatments were less than 2 h treatment.The treatments with supplemental lighting for 1 h and 2 h obviously raised net photosynthetic rate (P_n),stomatal conductance(G_s),intercellular CO₂ concentration(C_i),3 h treatment had little effects.The supplemental lighting treatments significantly enhanced optimal quantum yield of Φ_PSⅡ(F_v/F_m),actual photochemical efficiency of PSⅡ(Φ_PSⅡ),and photochemical quenching (q_P),lowered non photochemical quenching (NPQ),but showed little effect on initial fluorescence intensity Fc.Maximum net photosynthetic rate (P_max) and light saturation points (I_sat) were both raised,and light compensation point (I_c) was not affected obviously under these supplemental lighting treatments.These results indicated that proper supplemental lighting time could enhance the growth of tobacco leaves,accumulation of dry matter,chlorophyll content and photosynthesis,relieve the photoinhibition phenomenon,make full use of light energy,and improve the efficiency of photosynthesis in tobacco leaves.