Effects of light quality ratio on photosynthetic characteristics and quality of purple lettuce

Abstract

To explore the effects of different light quality ratios on the growth and development of purple lettuce, we used LED intelligent light control console as light source to study the effects of adding different proportions of red and blue light (1:1, 2:1, 4:1 and 1:2) to the white light on photosynthetic characteristics and commercial quality of purple lettuce (Lactuca sativa L. cv 'Zhongshu Purple Lettuce'). The results showed that when the ratio of red to blue light was 4:1, the chlorophyll content, RuBP carboxylase activity, electron transport efficiency of photosynthesis, net photosynthetic rate and growth were all significantly higher than that in control and other treatments, whereas the nitrate content was the lowest. When the ratio of red to blue light was 1:2, the contents of soluble protein, vitamin C, secondary metabolites such as anthocyanins, flavonoids, total phenolic compounds, and the contents of antioxidant capacity were significantly higher than those in the control and other treatments. We concluded that adding appropriate ratios of red to blue light to the white light could increase photosynthesis and improve commercial quality of purple lettuce.