Effects of light quality on the growth, mineral, and functional contents of green and red amaranth


  • Yukiko Tomari College of Agriculture, Tamagawa University, Tokyo, Japan https://orcid.org/0000-0001-9872-1890
  • Gauri Maharjan Horticulture LED Solutions, Signify, Eindhoven, Netherlands
  • Hiroyuki Watanabe College of Agriculture, Tamagawa University, Tokyo, Japan




Amaranth (Amaranthus tricolor L.) is a highly nutritious leafy vegetable, and the varieties have bright light green (green amaranth) and red (red amaranth) leaves. Light quality control is an important factor for high vegetable productivity in plant factories; however, the effects of light quality on growth, mineral compositions, and functional contents of amaranth have not been investigated. In this experiment, green and red amaranth seedlings were transplanted 28 days after sowing to a plant factory, with three LED treatments with different red/blue ratios and the presence or absence of far-red light, and cultivated for 24 days. Results showed that the growth of red amaranth was enhanced by the white and far-red light with the lowest blue light ratio, whereas the betalain and β-carotene contents in green amaranth were considerably enhanced by the middle blue light ratio. The highest iron content in both varieties was obtained under the light condition with the highest blue light ratio. Our findings suggest that amaranth yield can be increased, and their carotenoid, betalain, and mineral contents can be controlled by adjusting far-red and blue light intensities. The results of this study will help in light quality control during amaranth production in plant factories.






Plant breeding and cultivation