Monochromatic lights regulate the formation, growth, and dormancy of in vitro-grown Solanum tuberosum L. microtubers

Light quality is a key factor for plant growth. However, the effects of monochromatic lights on the formation, growth, and dormancy of microtubers have not been fully explored. Therefore, the present study was undertaken to evaluate the formation, growth, and dormancy of potato microtubers grown under monochromatic light emitted by light-emitting diodes (LEDs) at six wavelengths: 440 nm blue light (B-440), 460 nm blue light (B-460), 520 nm green light (G(520)), 590 nm yellow light (Y-590), 620 nm red light (R-620), and 660 nm red light (R-660). The results suggested that monochromatic light influenced microtuber formation, growth, and dormancy by regulating potato plantlet morphogenesis and enzyme activity, affecting the synthesis, transport, and transformation of photosynthetic metabolites, and altering the accumulation and distribution of biomass in various plant tissues. Y-590 did not favor microtuber formation and growth, whereas the other light conditions had differing advantageous effects. For instance, R-620 and G(520) induced rapid microtuber formation, and both G(520) and R-660 induced the growth of more microtubers in the middle and late growth stages, respectively. Meanwhile, B-440 and B-460 facilitated tuber growth and shortened the dormancy period of microtubers > 300 mg. Therefore, in potato agricultural production, specific light conditions may be applied at different growth stages of in vitro potato plantlets to shorten the production cycle and increase the number of valid microtubers (microtubers > 50 mg).