The Effects of Light Quality on Growth and Physiological Responses of Aquilaria crassna Tissue-Cultured Plantlets

This study evaluated the effects of red LED (RL), blue LED (BL), and white LED (WL) on the growth, physiological responses, and hormonal regulation of Aquilaria crassna tissue-cultured plantlets. Morphological assessment revealed that both RL and BL treatments reduced growth variation, with RL significantly promoting shoot elongation and secondary root development. Compared to WL, RL also enhanced the rooting rate and aboveground biomass. Analysis of hormones and physiological indicators indicated that RL and BL treatments decreased abscisic acid (ABA), cytokinin (CTK), and malondialdehyde (MDA) contents, while increasing indole-3-acetic acid (IAA), gibberellic acid (GA), soluble sugar levels, and superoxide dismutase (SOD) and catalase (CAT) activities, thereby altering hormone balance and antioxidant system stability. Correlation analysis revealed that light quality was significantly negatively correlated with ABA content, while root development was closely associated with hormonal balance and antioxidant capacity. A comprehensive evaluation using the entropy-weighted TOPSIS method ranked RL as the most favorable light condition for overall growth and development, with a closeness coefficient of 0.71. These findings provide a scientific basis for optimizing light quality management to improve the efficiency and quality of A. crassna tissue culture systems.