Vegetative propagation of the threatened East African yellowwood (Podocarpus falcatus)

Rooting in Podocarpus falcatus (Thunb.) Mirb. (syn. P. gracilior Pilg.) was studied using branch cuttings and whole seedlings harvested from 3-month-old, 2-year-old, 4-year-old and 8-year-old stockplants. The study was conducted in two separate propagators (two blocks) in which six different IBA treatments, viz. 0μg, 20μg, 40μg, 80μg, 160μg or 320μg IBA/cutting were administered to each of the 50–60 cuttings per treatment. The study found that cuttings from 3-month-old and 2-year-old stockplants responded well to IBA dosages between 20μg and 80μg/cutting, but were inhibited at higher concentrations. Treatments higher than 40μg/cutting significantly (P<0.01) inhibited rooting in cuttings derived from the 4-year-old and 8-year-old stockplants. Rooting was significantly (P<0.01) better in cuttings derived from 3-month-old and 2-year-old stockplants than from 4-year-old and 8-year-old stockplants. Indolebutyric acid significantly (P<0.01) shortened the time taken for 50% rooting-response in cuttings derived from 3-month-old and 2-year-old stockplants. Notwithstanding the poor rooting response, cuttings derived from 4-year-old and 8-year-old stockplants produced far more roots per cutting than those from 3- month-old and 2-year-old stockplants. Stecklings (plants derived from rooted cuttings) grew significantly (P