Vegetative propagation of Cordia alliodora (Ruiz & Pavon) Oken: the effects of IBA concentration, propagation medium and cutting origin

Abstract

The effects of different concentrations of IBA, rooting media and cutting origins on the rooting of leafy stem cuttings of Cordia alliodora (Ruiz & Pavon) Oken were investigated in three experiments using non-mist propagators. During the rooting period, changes in dry mass, photosynthetic rate, stomatal conductance and relative water content (RWC) of the cuttings were assessed. In Experiment 1, cuttings treated with 1.6% IBA achieved 70% rooting after 9 weeks. Bud growth in cuttings was inhibited by increasing concentrations of IBA, which were associated with higher final rooting percentages. No significant treatment differences in RWC or dry mass were found between IBA concentrations, although the dry mass of cuttings in all treatments tended to increase during the rooting period. In Experiment 2, higher rooting percentages were recorded in gravel (89%) and sand (88%) than in sawdust (76%). Although the water content of sawdust was relatively high, cuttings in this treatment displayed significantly lower stomatal conductances ( g s), which may be attributed to death of stem tissue resulting from anoxia. In Experiment 3, highly significant differences ( P < 0.01) were recorded between node positions with respect to rooting percentage, values ranging from 21.3% for Node 2 to 46.3% for Node 5 (basal). Cuttings actively photosynthesized during the rooting period, with photosynthetic rates ( P n) of 0.68–6.70 μmol CO 2 m −2 s −1 recorded. However, no clear relationship between P n and rooting ability was apparent. Contrary to previous studies with this species, it was concuded that C. alliodora cuttings may be rooted relatively easily using the propagation system described. However, the close relationships recorded between P n, irradiance and leaf-air vapour pressure deficit (VPD) suggest that propagator microclimate should be carefully managed if optimal rooting percentages are to be achieved.