Foliar Auxin Application Improves Adventitious Rooting of Wall Germander Cuttings

Abstract

Indole-3-butyric acid (IBA) is frequently used to promote adventitious root development in plant propagation from cuttings. We evaluated the effects of 0, 1000, or 3000 ppm IBA applied as a liquid foliar spray or talc-based basal dip on adventitious rooting of wall germander (Teucrium chamaedrys) cuttings. An initial experiment was conducted in Fall 2016, followed by a replication in Spring 2017. Two-dimensional root area, primary root count, root dry weight, and a rooting index (0 to 5 scale) were assessed as measures of root growth. By all metrics and for both experiments, cuttings benefited from IBA application and exhibited equal or greater root growth after the foliar spray treatment compared with the talc dip. In both experiments and for all metrics, the talc dip method achieved no greater root growth at 3000 ppm IBA than the foliar spray method at 1000 ppm IBA. These results suggest that for wall germander, IBA application by the foliar spray method is equal or superior to the talc dip method presently in widespread use in the horticulture industry.