The objectives of this study were to determine the effects of yellow light (Y), green light (G), and two blue lights (B) at different wavelengths in conjunction with red light (R) on the growth and morphogenesis of potato plantlets in vitro. Randomized nodal explants were cut into 1.0–1.5 cm pieces and were grown under five different light conditions: fluorescent white light (FL); the combined spectra of R, Y, and B at 445 nm (R630B445Y); the combined spectra of R, G, and B at 445 nm (R630B445G); the combined spectra of R, Y, and B at 465 nm (R630B465Y); and the combined spectra of R, G, and B at 465 nm (R630B465G). Morphogenesis and physiological parameters were investigated. The results showed that R630B445Y and R630B465Y increased the fresh weight (FW), dry weight (DW), stem diameter, blade number, leaf area, specific leaf weight (SLW), and the health index of potato plantlets in vitro; root activity increased significantly; and soluble sugar, soluble protein, and starch also increased. The addition of Y to the combined spectra of R and B contributed to the growth, development, and morphogenesis more than the combined spectra of R and B with G, and B at 445 nm was more effective at promoting plant growth than was B at 465 nm.
Ruining Li, Wenwen Huang, Xiaoxiao Wang, Xiaoying Liu and Zhigang Xu
Ruining Li, Jiahuan Long, Yongzhe Yan, Jiaming Luo, Zhigang Xu and Xiaoying Liu
Monochromatic light and wide-band white light both affect plant growth and development. However, the different effects between monochromatic light and addition white light to monochromatic light on the formation, growth, and dormancy of microtubers have not been fully explored. Therefore, we evaluated these effects using in vitro potatoes grown under pure blue and red lights and a combination of blue light and red light supplemented with white light, respectively. Current results suggested that light spectra influenced microtuber formation, growth, and dormancy by regulating potato plantlet morphogenesis, affecting the synthesis and transportation of photosynthetic metabolites, and altering the accumulation and distribution of biomass in various plant tissues. Monochromatic lights and the combined spectra had differing effects. For instance, monochromatic red light induced the growth of more microtubers, whereas addition white light to red light decreased number but increased weight of microtubers. Meanwhile, monochromatic blue light facilitated tuber growth, whereas addition white light to blue light decreased microtubers weight but increased microtuber number. In addition, composite lights of addition white light to monochromatic red and blue lights both extended the dormancy period, and monochromatic blue light shortened the dormancy period of microtubers >300 mg. Therefore, in microtuber agricultural production, specific light conditions may be applied at different growth stages of in vitro potatoes to increase the number of effective microtubers (>50 mg) and to satisfy storing requirement of seed microtubers.