Improvement of Rooting in Forsythia × intermedia Cuttings by Plant Growth Regulators

Asexual propagation through cuttings is an appropriate method used for most ornamental plants. Success in increasing the percentage of rooting, reducing root emergence and increasing proliferation efficiency depends on several factors like plant growth regulators, especially auxins. Rooting of Forsythia × intermedia is difficult and requires specific hormonal treatments and proper cultivation beds. This work evaluated the rooting of Farsythia × intermedia cuttings under the action of different concentrations of plant growth regulators. The cuttings consisted of 15 cm long shoots with their basal leaves removed. The basal part of the cuttings was treated with 0, 500, 1000 and 1500 mg l -1 IBA and/or NAA. Stem cuttings were kept in hormones solution for 10 seconds. Then, they were planted in rice husk, sand and perlite as cultivation bed under greenhouse conditions. After two months, the percentage of rooted stem cutting, root number per stem cuttings, root length and root fresh and dry weights were determined on stem cuttings. The highest rooting percentage (51%) was obtained in cuttings treated with 1000 mg l-l IBA + 1500 mg l -lNAA. The maximum root number was obtained in cuttings treated with 1500 mg l -l IBA + 1500 mg l -1 NAA. The maximum root length (4.66 cm) was obtained in stem cuttings treated with 500 mg l -1 IBA + 1000 mg l -1 NAA