Propagation of Ulmus parvifolia ‘Emerald Prairie’ by Stem Cuttings

Abstract

Abstract Stem cuttings of Ulmus parvifolia Jacq. ‘Emerald Prairie’ (‘Emerald Prairie’ lacebark elm), consisting of 7.5 to 10 cm (3 to 4 in) terminal shoot portions, were collected four times throughout the year from mature stock plants and treated with the potassium (K) salt of indole-3-butyric acid (K-IBA) ranging from 0 to 20,000 ppm (2.0%). Rooting percentages were affected greatly by K-IBA treatment and stock plant growth stage. Little to no rooting was observed without K-IBA application, whereas overall rooting for treated softwood, early semi-hardwood, late semi-hardwood, and hardwood, cuttings was 92, 86, 87, and 8%, respectively. Mean root number varied by growth stage and K-IBA concentration. Higher concentrations of K-IBA increased the number of roots on rooted cuttings except for hardwood cuttings. In general, rooting percentage and mean root number were highest at the softwood stage with 15,000 or 20,000 ppm (1.5 or 2.0%) K-IBA, resulting in 97% rooting and 15 or 22 roots per rooted cutting, respectively. However, leaf abscission was high on softwood cuttings. Semi-hardwood cuttings achieved similar rooting percentages and may exhibit better survival and growth due to greater leaf retention.