Biochemical and Physiological Changes during Early Adventitious Root Formation in Chrysanthemum indicum Linné...

Chrysanthemum indicum is an important ornamental and medicinal plant that is often difficult to propagate commercially because of its poor germination and low seed viability. This plant is mostly propagated by cutting, but the rooting is slow and non-uniform. The present investigation evaluated the regeneration capacity of stem cutting by examining the influence of auxins, growth medium, temperature, and explant type on adventitious root formation in C. indicum. The auxin-treated cuttings were planted in different growth substrates under greenhouse conditions. Among the different auxins tested, indole-3-butyric acid (IBA) more effectively induced roots. The cutting position of stock plants influenced rooting capacity. Cutting the stock plants from the apical region enhanced root number and length in the explants. Among the different explant types, apical stem cuts with 2000 ppm IBA produced a significantly higher number of adventitious roots when grown in vermiculite and perlite (V + P) at a ratio of 1:1 at 25 °C. High-performance liquid chromatography (HPLC) analysis revealed that protocatechuic acid, gentisic acid, chlorogenic acid, biochanin A, salicylic acid, caffeic acid, glycitein, and luteolin were the most dominant phenolic compounds present in C. indicum. These results indicate that IBA treatment promoted the synthesis and accumulation of phenolic compounds in C. indicum stem cuttings at the time of root formation. The present results demonstrate that applying auxins is essential for early root initiation and higher rooting success and thus may be beneficial for vegetative C. indicum propagation.