Effects of different proportions of red and blue light on the growth and photosynthesis of tomato seedlings

Abstract

In order to explore the mechanism of response of growth and development of tomato seedlings to the combination of red and blue light, the light-emitting-diodes (LEDs) as precision modulation light sources were used in this study with 7 treatments including red (R) light, blue (B) light and combination of R+B light (9R1B, 6R1B, 3R1B, 1R1B, 1R3B), white (W) light as control, and the effects of different proportions of R and B light on the growth, photosynthetic pigment content, photosynthetic characteristics, chlorophyll fluorescence and root activity of tomato seedlings with variety of 'SV0313TG' as experiment material were studied. The results showed that there were significant differences in growth of tomato seedlings under treatments of different proportions of R and B light. The plant height, specific leaf area and intercellular CO2 concentration of tomato seedlings were significantly promoted by R light, while Fv/Fm and χPS2 were decreased, the root growth was inhibited as the root activity declined, so that the seedling index was reduced. The seedling growth was significantly suppressed under B light and the chlorophyll content was decreased, while the chlorophyll a/b was enhanced. Furthermore, combination of R+B light was be-neficial to the growth and development of tomato seedlings, and the plant dry mass, chlorophyll content and photosynthetic performance were significantly increased under 3R1B. In addition, seedlings grew strongly and had the highest value of seedling index under this treatment. In conclusion, the combination of R+B light could promote photosynthetic pigment content and photosynthetic efficiency in leaves of tomato seedlings, as well as plant growth, especially for treatment of 3R1B.