Dynamics of industrial hemp vegetative growth and metabolite accumulation in response to light intensity.

• Morphological characteristics and metabolite profiles of hemp exhibit distinct responses to varying light intensities. • Amino acids, soluble protein, carbohydrates, and plant growth influenced by light intensity. • Desired metabolites contents can be achieved by changing light intensity. • Optimum light intensity could be valuable in the pharmaceutical and nutritional field. Industrial hemp (Cannabis sativa L.) is a high-yielding cash crop with strong stress resistance, and its fibrous and metabolic profile holds significant development potential. In this study, we measured various agronomic traits, amino acids, saccharides, and their derivatives under four different light intensities (30 μmol·m−2·s−1, 80 μmol·m−2·s−1, 130 μmol·m−2·s−1, 180 μmol·m−2·s−1). Results showed that plant height decreased with increasing light intensity and reached a minimum at 180 μmol·m−2·s−1, which was 27 % less than the control treatment. Further, stem diameter increased by 52 %, leaf fresh weight by 130 %, stem fresh weight by 116 %, and root fresh weight by 264 % were at their maximum at 130 μmol·m−2·s−1. Plant dry weight of leaf (113 %), stem (214 %), and root (427 %) were also found to be maximum at 130 μmol·m−2·s−1. Metabolic results revealed that the free amino acid content was 10 %, 61 %, and 60 % higher under 30 μmol·m−2·s−1 compared to 80, 130, and 180 μmol·m−2·s−1. Additionally, soluble protein contents were 42 %, 81 %, and 77 % higher under 30 μmol·m−2·s−1 compared to 80, 130, and 180 μmol·m−2·s−1. In contrast, the soluble sugar contents were 42 %, 61 %, and 75 % higher than in the other three treatments. In conclusion, industrial hemp morphological characteristics and metabolite profiles exhibit distinct responses to different light intensities. To achieve desired outcomes, it is imperative to carefully choose an optimized light intensity specifically tailored to align with the defined objectives. These findings provide a foundation for a deeper understanding of the characteristics of industrial hemp, optimizing cultivation techniques, and investigating the impact of light intensity on industrial hemp vegetative period growth, amino acids, and saccharides. [ABSTRACT FROM AUTHOR]