Effects of light quality, light intensity, and photoperiod on growth and yield of cherry radish grown under red plus blue LEDs

Abstract

For more plant species to be suitable for plant factory production, their optimal light regimes need to be optimized. We evaluated the effects of light quality, light intensity, and photoperiod on the growth and yield of cherry radish grown under red plus blue LEDs in a controlled environment. Radish plants were cultivated under two light qualities with different red:blue ratios (1R:1B, 2R:1B) at three light intensities (180, 240, 300 μmol m−2 s−1) or two photoperiods (12 h/12 h, 16 h/8 h), respectively. The light quality 2R:1B increased root diameter, root volume, and the biomass of shoot and root compared to light quality 1R:1B under a light intensity of 240 and 300 μmol m−2 s−1, but the growth differences between 1R:1B and 2R:1B were significant when the light intensity was 240 μmol m−2 s−1. New leaf chlorophyll content, root growth indices and the root-shoot ratio increased with light intensity. Cherry radish only formed storage roots with commercial value when light intensity was equal to or over 240 μmol m−2 s−1. The root diameter, root volume, root-shoot ratio, and the biomass of shoot and root of plants grown in the 2R:1B treatment was significantly higher than those in the 1R:1B treatment under the 16 h/8 h photoperiod. However, no significant difference was observed in the 12 h/12 h photoperiod. These results indicated that light regime in combination with a light intensity between 240 and 300 μmol m−2 s−1, the light quality 2R:1B, and a 16 h/8 h photoperiod produced appropriate growth of cherry radish in plant factory settings using an LED light source. In conclusion, the production of commercial storage roots in cherry radish is primarily dependent on light intensity, followed by light quality and photoperiod. Furthermore, the effectiveness of light quality regulation of storage roots was highly depended on light intensity and photoperiod.