Energy-efficient light spectrum modulation for optimising biochemical composition, resource utilisation and physiological responses of pak choi in multi-tier production system

Light spectrum optimization plays a crucial role in improving the growth, physiological performance and biochemical composition of pak choi cv. Choko under controlled environments. The optimal LED spectral combination for enhancing pak choi growth and quality in controlled environments remains unclear. This study revealed the effects of different light spectral treatments on plant growth responses at 40 days after transplanting (DAT) and biochemical at 10, 25 and 40 DAT. High spectral selectivity, coupled with optimized optical power, enables the optimization of plant growth and development. The white + red + blue (W + RB) treatment significantly outperformed all other treatments, exhibiting the highest plant height (20.51 cm), leaf area (452.36 cm 2 ) and number of leaves (16.25), along with enhanced biomass accumulation and photosynthetic efficiency. It achieved the highest net photosynthetic rate (26.67 μmol CO 2 m −2 s −1 ), stomatal conductance (0.67 μmol CO 2 m −2 s −1 ) and transpiration rate (7.94 mol m −2 s −1 ) indicating optimal photosynthetic conditions. Additionally, nutrient use efficiency was highest under W + RB with per plant nitrogen uptake of 674.88 mg in shoots and 21.41 mg in roots, along with the highest phosphorus and potassium uptake. Biochemical analysis revealed an increase in total soluble sugars (1.15 mg g −1 ) and antioxidant activity, along with the lowest nitrate content (1.02 mg g −1 DW). The superior energy efficiency, with the lowest energy consumption (10.88 kWh per crop cycle) and highest light energy efficacy (9142 lm W −1 ) were also observed in the combination of white, red and blue light combination, highlighting its effectiveness in optimizing plant growth while minimizing energy input offering a scalable and sustainable lighting solution for indoor crop production. • Energy-efficient lighting reduced input demand while maximizing plant productivity. • W + RB boosts antioxidants, enzymatic activity, glucosinolates and sugar accumulation. • Enhanced nutrient uptake ensures sustainable resource use in controlled environment. • W + RB improved luminous efficacy, water utilization and physiological performance. • Spectral engineering enabled climate-smart, resource-efficient indoor crop production.