Vegetative Propagation of <i>Bombax</i><i> </i><i>costatum</i> Pellegr. Vuillet (Malvaceae) by Root Segment Cutting: Effect of Substrate and Length of Cuttings in the Guinean Savannas Highlands (Adamawa Cameroon)

Abstract

<i>Bombax</i><i> </i><i>costatum</i> is a native species of significant socioeconomic importance in the Guinean savannah highlands of Cameroon. This study aimed to evaluate the effects of substrate type and root cutting length on the regenerative capacity of root segments, specifically their ability to produce new leafy shoots and adventitious roots. Root systems were excavated from adult mother plants, and fragments of lateral roots were collected, transported in a cooler and processed in a nursery. The root segments were cut into cuttings of 10, 15, and 20cm in length. These root segment cuttings were then inserted in three substrate mixtures: sand/sawdust, topsoil/sawdust, and pure fine sand. The experimental design was a split-plot with three replications. 270 root segment cuttings were used. Results indicated that the substrate type significantly (p<0.05) influenced bud break, with the highest percentage observed in the sand/sawdust mixture (56.7±3.9%) and the lowest in the topsoil/sawdust mixture (41.11± 1.91%). Similarly, cutting length had a significant effect (p<0.05), with the highest bud break rate achieved by 20cm cuttings (61.66 ±1.96%) compared to 10cm cuttings (48.95 ± 1.87%). Rooting rates were also significantly affected by substrate (p<0.05), being highest in the sand/sawdust mixture (51.97±2.72%) and lowest in the Ts/Sd mixture (21.28 ± 2.81%). The 20cm cuttings promoted the highest rooting rate (64.61±0.27%), which was significantly higher (p<0.05) than those of the 10cm cuttings (18.35±2.72%). In conclusion, a sand/sawdust substrate mixture and a cutting length of 20cm were identified as the most favourable conditions for the vegetative propagation of <i>Bombax</i><i> </i><i>costatum</i>. These findings demonstrate the species' potential for domestication through root cutting techniques.