The Role Of Selected Growth Regulators And Light Source And Quality In The In Growth, Multiplication, And Enhancement Of Bioactive Compounds In Chrysanthemum Morifolium Plant In Vitro

Abstract

The study was carried out in the Central Laboratory for Plant Tissue Culture at the College of Agricultural Engineering Sciences, University of Baghdad, between October 2023 and December 2024. Its aim was to propagate Chrysanthemum morifolium through tissue culture techniques and to explore the influence of specific growth regulators, as well as light source and quality, on both the plant's propagation and its production of secondary metabolites. Four experimental stages were implemented. The first examined the effect of varying sodium hypochlorite (NaOCl) concentrations (0, 5, 10, and 15 mL per 100 mL) on sterilizing plant material. The second investigated how different levels of BA and NAA impacted shoot initiation and multiplication. The third stage assessed the influence of light source and spectral quality on the number and length of shoots, chlorophyll levels, and phenolic compound content. Four levels of BA (0, 0.5, 1 and 1.5 mg L⁻¹) and four concentrations of NAA (0, 0.1, 0.3 and 0.5 mg L⁻¹) were combined with five lighting treatments: white fluorescent, white LED, blue LED, red LED, and a combination of red and blue LED. The best outcome of sterilization treatment was observed by NaOCl treatment at 15 mL for 15 min with single node that produced highest response (100%) on 0.5 mg L⁻¹ BA amended media. A significant interaction between BA and NAA concentrations was observed, where 1 mg L⁻¹ BA with 0.2 mg L⁻¹ NAA yielded the highest average number of shoots (15 per explant), while 0.5 mg L⁻¹ BA combined with 0.3 mg L⁻¹ NAA produced the longest shoots, averaging 5 cm. White LED light promoted the greatest shoot proliferation (20 shoots per explant), whereas red LED led to the longest shoot growth (3 cm). The red-blue LED mix resulted in the highest chlorophyll content (111.5 mg per 100 g) and supported the greatest accumulation of phenolic compounds, including quercetin, gallic acid, rutin, kaempferol, luteolin, and apigenin, with values of 59, 71.6, 64.5, 50.6, 22.6, and 32.9 µg g⁻¹, respectively.