Rooting capacity of two rose species in relation to hormones and other factors

Abstract

Rooting performance of two rose species were compared. The effect of sucrose, nitrogen, IBA, presence of leaves and maturity of the cuttings on rooting were examined and the endogenous levels of IAA, GA and cytokinins and rooting co-factor activity were determined in their methanolic extracts. The determination for ABA did not yield results.

R. multiflora one-node cuttings rooted better than R. bracteata ‘Mermaid’. Sucrose and IBA treatments improved rooting of R. multiflora while nitrogen inhibited it.

Rooting of R. multiflora stem cuttings were influenced by the number of leaves present in the cuttings, maturity and IBA concentration. The presence of leaves improved rooting. Harder stems (8th-19th node) rooted better than very young ones (0-7th node) while 750 ppm IBA significantly induced better rooting than 1500 ppm IBA.

Significant interactions were obtained between maturity x hormone concentration and number of leaves x hormone concentration. It appears that more mature stem cuttings will root better if IBA is present while the presence of leaves seems to replace the favourable effect of IBA.

Cuttings of R. multiflora are probably characterized by high concentrations of GA and low levels of IAA and cytokinin but greater rooting co-factor activity. Apparently R. bracteata 'Mermaid' has high GA and cytokinin levels and low free IAA plus lack of rooting co-factor activity and presence of inhibitors.