Methods of Auxin Application in Cutting Propagation: A Review of 70 Years of Scientific Discovery and Commercial Practice

Abstract

The discovery of auxins as plant growth regulating chemicals in the 1930s and their ability to stimulate adventitious rooting in stem cuttings marked a major milestone in the modern history of plant propagation. Basic and applied research conducted during the past 70 years has provided information regarding absorption and translocation of auxin in cuttings, as well as the effects of timing of auxin application, methods of auxin application, type of auxin, and concentration of auxin on the rooting response of cuttings. The basal quick-dip method, the powder application method, and the dilute soak method have been the most commonly used methods for applying auxin to cuttings in commercial horticulture over the past 7 decades, with the first two methods still in common use today. In addition, a wide variety of other auxin application methods have been reported beginning in the 1930s and continuing to the present. Some of these methods remain primarily of historical interest, several find limited use in commercial horticulture, and others show potential for greater use in the future. Opportunities exist for further development of auxin application techniques that can enhance plant quality, efficiency and productivity of the cutting propagation process, and worker safety. This review provides horticulturists, from the academic researcher to the commercial propagator, with an exploration of auxin application methods over the past 70 years, along with an examination of the physiological response of cuttings to applied auxin and an overview of issues leading to future opportunities.

Evaluation of substrate composition and exogenous hormone application on vegetative propagule rooting success of essential oil hemp (Cannabis sativaL.)

“…Treating cuttings with auxin increases formation of roots, reduces time to root initiation, and improves rooting uniformity [14, 17]. Valued for their extensive history of use and consistent rooting response, indole-3-butryic acid (IBA) and 1-naphthalenacetic acid (NAA) are common auxins utilized in commercial propagation of plants [17, 18].…”

“…Treating cuttings with auxin increases formation of roots, reduces time to root initiation, and improves rooting uniformity [14, 17]. Valued for their extensive history of use and consistent rooting response, indole-3-butryic acid (IBA) and 1-naphthalenacetic acid (NAA) are common auxins utilized in commercial propagation of plants [17, 18]. Auxin is commonly applied to cuttings via liquid solution, powder formulations, or a combination of both methods [14], although liquid solutions are generally more effective than powder formulations [19, 20].…”

Propagation of Jasminum parkeri: A Critically Endangered Wild Ornamental Woody Shrub from Western Himalaya

“…In the present investigation, the sub-apical semi-hardwood stem cuttings of J. parkeri showed good potential for root induction, but varied with auxin concentrations (1000 to 4000 ppm). Auxin is commonly applied in the vegetative propagation of plants because it can stimulate adventitious rooting in cuttings; increase the overall rooting percentage, root number, and quality of roots; and encourage rooting uniformity [11][12][13]. The stem cuttings were most responsive to NAA at 3000 ppm concentration for rooting percentage, total root length, and number of primary roots.…”

The Induction of Adventitious Roots Regeneration before Transplanting Rootless Ficus elastica Heritage Tree

“…The best IBA concentration for ARs varies by plant species and environmental conditions. It ranges between 50 mg L −1 and 8000 mg L −1 , depending on the plant type, application method, and medium [19,20]. For quick dip or paint methods on stem cuttings, 2000 to 4000 mg L −1 seemed to be the most commonly used concentration.…”