Lighting conditions affect the growth and glucosinolate contents of Chinese kale leaves grown in an aeroponic plant factory

Controlled environment agriculture in artificial lighting facilities has enormous potential for improving crop quality and production capacity. Light conditions, including light quality, photoperiod, and light intensity, significantly affect the growth and functional component accumulation of crops. Several studies have been conducted to assess the effects of light conditions on different crops, but research on Chinese kale has been limited, especially its hydroponic growth in plant factories. The objective of this study was to investigate the effects of light quality, photoperiod, and light intensity on Chinese kale growth and glucosinolate content during different growth stages of cultivation in a plant factory. Different light treatments, including four types of light (red (R): blue (B): white (W), R:W, R:B, and fluorescent), five photoperiods (12/12, 14/10, 16/8, 18/6, and 20/4 h), and five light intensities (100, 130, 160, 190, and 220 µmol ­m⁻² ­s⁻¹) were implemented, while the ambient environmental parameters were maintained using a wireless monitoring and control network system. After specific periods of transplantation, samples were collected for growth evaluation and glucosinolate estimation. A two-way analysis of variance (ANOVA) and Tukey’s multiple mean range test were conducted to compare the means and determine statistical significance. Better leaf growth rate was observed under the R:B light source. Total glucosinolates were greater under R:B (63.38 µmol ­g⁻¹ DW) and R:B:W (118.51 µmol ­g⁻¹ DW) LED combinations at first and second samplings, respectively. A cyclic photoperiod of 16/8 and 18/6 h fostered optimal growth, but greater glucosinolate content was observed under 18/6 and 14/10 photoperiods at the first and second sampling times, respectively. Although light intensities of 160 and 220 µmol ­m⁻² ­s⁻¹ were good for physical growth, 160 and 130 µmol ­m⁻² ­s⁻¹ were better for glucosinolate accumulation at the first and second sampling times, respectively. The current findings may be of use for cultivating high quantities of nutrient-rich Chinese kale in protected crop cultivation facilities using artificial lighting.