STUDY ON in vitro INDUCTION OF ROOTING AND CHANGES IN ENDOGENOUS HORMONE CONTENT OF Lagerstroemia indica ‘ZIJINGLING’

Different media had different effects on the induction of rooting of Lagerstroemia indica ‘Zijingling’. The aims of this study were to identify the best rooting medium, determine the changes in endogenous hormone content in aseptic seedlings of ‘Zijingling’, and then analyze its role in the rooting process, to improve the rooting rate. Using a test tube seedling of ‘Zijingling’ as the experimental material, the tissue cells were observed via paraffin sectioning, and the changes in endogenous hormone content during the rooting process were determined using high-performance liquid chromatography. The results showed that 1/2 MS Medium had the most significant effect on rooting in the basic medium. The promoting effects of different auxins on rooting decreased in magnitude in the order 3-Indolebutyric acid (IBA) > Naphthalene acetic acid (NAA)> Indole-3-aceticacid (IAA). The optimal rooting medium was 1/2 MS + 0.6 mg L-1 IBA+ 15 g L-1 sucrose + 5 g L-1 agar + 200 mg L-1 activated carbon , and the highest induction rate of adventitious roots was 92.5%. The rooting of ‘Zijingling’ is classified as a primordial type of induced rooting. Exogenous IBA content promoted an increase in endogenous IAA and Gibberellic acid (GA3) contents. High contents of IAA, GA3, and Abscisic acid (ABA) and low content of Zeatin riboside (ZR) promoted the growth of adventitious roots, whereas high contents of IAA and ZR, and low contents of GA3 and ABA were required for the induction of root primordia. High levels of IAA/ZR and low levels of IAA/ABA promoted the differentiation of root primordia. However, low levels of IAA/ZR and high levels of IAA/ABA promoted adventitious root elongation.