Chiang Mai Journal of Science

     Effects of LED illumination on callus induction from petals of Karaked and Scarlet chrysanthemums cultivated in MS medium supplemented with 2 mg/I NAA and 4 mg/l Kinetin, under white LED light (PPFD 30±2 µmol/m2/s) and red to blue light in the ratios 30:10, 40:15, and 30:3 (PPFD 50±2 µmol/m2/s) for 16 h. It was determined that a light ratio throughout 4 weeks culture period had no impact on the fresh weight of callus. Conversely, varying light proportions yield distinct callus dry weights. Upon evaluating cultivar parameters, it was determined that ‘Karaked’ exhibited more fresh and dry weight compared to the callus of the ‘Scarlet’. Analysis of Karaked's callus showed that callus cultured under 30:3 red to blue LED light exhibited the largest concentrations of all photosynthetic pigments, the greatest levels of malondialdehyde (MDA) and total phenolic compounds, and the lowest EC50 value for DPPH free radical inhibition. In the case of the Scarlet chrysanthemum, following 8 weeks of callus induction, it was observed that a light ratio of red to blue at 40:15 yielded the maximum concentrations of chlorophyll a and carotenoids. No statistical difference was seen in the quantity of chlorophyll b. The MDA content of Scarlet’s callus cultivated under white LED light was the highest, and the EC50 value for DPPH free radical inhibition was also the highest. Callus produced under red to blue LED light ratios of 30:10, 40:15, and 30:3 exhibited greater quantities of phenolic compared to callus cultured under white LED light.