Abstract: In order to explore the effects of different red and blue LED light intensity on the growth and nutritional quality of purple leaf lettuce, purple leaf lettuce ‘Purple Rosa’ was used as material in the experiment. Under the 1:1 ratio of red and blue light condition,four light intensities 50 μmol/(m²·s)(RB50), 100 μmol/(m²·s)(RB100), 150 μmol/(m²·s)(RB150) and 200 μmol/(m²·s)(RB200) were processed. The growth, nutrient quality and photosynthetic characteristics of lettuce leaves were collected from four light intensities. The results showed that under RB150 treatment, purple leaf lettuce had the largest biomass, higher yield, the highest carotenoid content. At 25 d after transplanting, the highest activity of SOD, CAT and POD and the strongest antioxidant capacity. Under the treatment of RB200, the soluble protein content of leaves increased by 80.30% and 40.64%, and the anthocyanin content of leaves increased by 51.5 times compared with RB50 treatment. Moreover,chlorophyll content, leaf net photosynthetic rate, and vitamin C content of RB200 were significantly higher than other treatments and nitrate content was the lowest. RB200 treatment could promote the increase of chlorophyll a, chlorophyll b and total chlorophyll in purple leaf lettuce, so as to promote the accumulation of photosynthetic pigment and the progress of photosynthesis.Therefore, under the condition of the red and blue light ratio 1:1, light intensity was higher when the beneficial to the improvement of the quality of purple leaf lettuce, appropriately increased light intensity can enhance purple leaf lettuce biomass and improve the nutritional quality, according to the different requirements in the process of production, by controlling the plant factory in light intensity, make purple leaf lettuce higher photosynthetic rate and excellent quality.

Key words: Purple leaf lettuce, LED light source, Light intensity, Quality, Antioxidant capacity

CLC Number: 

• S636.01

• S626