Cutting propagation of 4 Florida native taxa of wild coffee (Psychotria spp.)

Abstract

Wild coffee (Psychotria nervosa Sw. [Rubiaceae]), softleaf wild coffee (Psychotria tenuifolia Sw.), and Bahama wild coffee (Psychotria ligustrifolia (Northrop) Millsp.) are evergreen shrubs with attractive foliage, fragrant white flowers, and colorful fruit. A cutting propagation study was conducted to determine the effects of auxin concentration on rooting of these 3 species, and a dwarf form, Psychotria nervosa ‘Little Psycho’. We treated semi-hardwood stem cuttings of each taxa with one of 3 talc indole-3-butyric acid (IBA) concentrations (0, 8000, and 16,000 mg/kg) and evaluated for rooting responses. Cuttings for all taxa rooted by 8 wk under mist. Root system quality values increased for P. nervosa ‘Little Psycho’ and P. tenuifolia with auxin application, while root system quality values for P. ligustrifolia and P. nervosa were similar among auxin treatments. Percentage of cuttings with roots was similar among taxa and increased with IBA at 8000 and 16,000 mg/kg compared to the control. Both root length and root number were influenced by auxin application, and the effects of auxin differed among taxa. Except for P. nervosa, all taxa treated with IBA produced roots that were longer than control cuttings. Auxin application increased root number compared to the control for P. ligustrifolia, P. nervosa, and P. nervosa ‘Little Psycho’. Psychotria tenuifolia had the greatest number of cuttings with 25 or more roots, but root number did not differ regardless of auxin concentration. Results confirm that native Florida Psychotria taxa are ideal candidates for vegetative propagation by semi-hardwood stem cuttings.