Effects of green and red lights on the growth and morphogenesis of potato (Solanum tuberosum L.) plantlets in vitro

The objectives of this study were to determine the effects of green light (G) and two red lights (R) of different wavelengths on the growth and the morphogenesis of potato plantlets in vitro. Randomized nodal explants were grown under five different light conditions: fluorescent white light (FL); the combined spectrum of blue light (B), G, and R at 630 nm (R630BG); the combined spectrum of B, G, and R at 660 nm (R660BG); the combined spectrum of B and R at 630 nm (R630B); and the combined spectrum of B and R at 660 nm (R660B). Morphogenesis, physiological parameters and leaf anatomical structure of potato plantlets in vitro were investigated. The results showed that R630BG and R660BG increased stem diameter and leaf area, and increased the amounts of chlorophyll, soluble sugar, soluble protein and starch in potato plantlets in vitro. Most of the stomata under R660BG were elliptical in shape. Leaves of potato plantlets in vitro grown under R630BG and R660BG had a distinct upper epidermis layer and palisade parenchyma layer. The addition of G to the combined spectrum of R and B contributed to the growth and development of potato plantlets in vitro more than the combined spectrum of R and B without G, and R at 660 nm was more effective in promoting plant growth than R at 630 nm.