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 (R 630 BG); the combined spectrum of B, G, and R at 660   nm (R 660 BG); the combined spectrum of B and R at 630   nm (R 630 B); and the combined spectrum of B and R at 660   nm (R 660 B). Morphogenesis, physiological parameters and leaf anatomical structure of potato plantlets in vitro were investigated. The results showed that R 630 BG and R 660 BG 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 R 660 BG were elliptical in shape. Leaves of potato plantlets in vitro grown under R 630 BG and R 660 BG 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.