Bougainvillea spectabilis ‘Yunnan Purple’ is a relatively cold-tolerant variety, but its low pollen viability and poor seed set have limited large-scale reproduction. To establish an efficient propagation protocol, cuttings from three types of Bougainvillea spectabilis ‘Yunnan Purple’ were treated with varying concentrations of exogenous indole-3-butyric acid (IBA). Rooting parameters, growth indicators, and physiological metrics were measured, and the optimal treatment was identified through comprehensive membership function evaluation. The results showed that cutting types significantly influenced rooting, root development, plant growth, organic compound content (soluble sugars, starch, and protein), and abscisic acid (ABA) content. Conversely, IBA concentration significantly affected rooting, root architecture, polyphenol oxidase (PPO) activity, and the levels of indole-3-acetic acid (IAA) and Brassinolide (BR). This comprehensive evaluation identified lignified shoots (LS) treated with 100 mg/L IBA (LS-100) as the optimal protocol, which achieved a rooting rate of 63% and significantly improved root formation, plant growth, root activity, organic compound content, PPO activity, and the levels of IAA and BR. This study provides valuable insights and technical guidance for the large-scale cutting propagation of Bougainvillea spectabilis ‘Yunnan Purple’.
Hu et al. (Wed,) studied this question.