Objective Effects of artificial light exposure on growth, photosynthesis, and carbon metabolism of chili pepper seedlings were studied.

Method Shijilonglong 2 chili pepper plants were grown under the artificial lighting using red (R) and blue (B) lamps in combinations of 2∶1 (T1), 3∶2 (T2) or 3∶1 (T3), along with white light as control (CK).When the two leaves of pepper are in one center, add light from 8:00 to 18:00 , effects of different light qualities on pepper seedlings,plant height, stem diameter, leaf length, leaf width, leaf area, number of leaves; chlorophyll content (chlorophyll a, chlorophyll b, chlorophyll a+b); net photosynthetic rate (Pn), intercellular carbon dioxide concentration (Ci), stomatal conductance (Gs) and transpiration rate (Tr); effects of sugar content (fructose, glucose, sucrose, starch content) and key enzyme activities of carbon metabolism (sucrose synthase (SS), sucrose phosphate synthase (SPS), neutral invertase (NI) and soluble acid invertase (AI)) 【Result】Comparing to CK, the lighting of various R+B lamp combinations grew taller seedlings in 20d、30d、40 d. The plants were 26.22% taller under T1, 27.29% under T2, and 8.49% under T3. On the 30^th day, those under T2 were 10.50% and those under T3, 3.28% taller. The seedling leaves were significantly longer in 20–40 d under the combination lighting, and significantly wider, larger, and more numerous under T3. The chlorophyll a, chlorophyll b, and total chlorophyll of the seedlings increased by 14.52%, 60.00%, and 52.17%, respectively, under T3, while the net photosynthetic rate, intercellular CO₂ concentration, and stomatal conductance became significantly 44.65%, 43.45%, and 60.00%, respectively, higher under T2. The contents of glucose, sucrose, and starch peaked with 50.14%, 49.20%, and 34.17%, respectively, increases under T2. Meanwhile, the neutral invertase activity rose significantly 21.72% under T3, and the sucrose synthase activity 32.29% under T1.【Conclusion】Chili pepper seedlings grew robustly when exposed to the combined R and B lamps in 3:2 ratio (T2) that boosted photosynthetic rate and sugar content to significantly enhance the carbohydrate transformation and accumulation in the plants.