Plant Growth Regulator and Temperature Affect Echeveria and Andromischus Leaf Cutting Rooting and Axillary Shoot Formation

Fourteen Echeveria cultivars and Andromischus critatus stem cuttings were received on November 5.   Forty to sixty leaf cuttings of each species/cultivar were harvested from stem cuttings and allowed to air dry one day. Ten to 15 leaf cuttings of each species/cultivar were dipped (base only) in 1000 ppm 1-naphthaleneacetic acid (NAA), 1000 ppm indole-3-butyric acid (IBA), 500 ppm 2-Chloroethylphosphonic acid (ethephon), or water.  Leaf cuttings were then placed in petri dishes (air only) and placed in growth chambers adjusted to maintain a 10, 16, 22 or 28C leaf temperature until cuttings rooted (roots length >1 cm) or until 60 d had passed.  Data were collected on time to root, un-rooted cutting number, and shoot number per cutting when rooted. Percent rooted cuttings was calculated from this data. The first nine rooted leaf cuttings were planted in soilless media in a greenhouse (22/18C day/night temperature) on the day those leaf cuttings were considered ‘rooted’, and percent survival of those rooted cuttings was collected 90 d later.  Leaf cutting rooting varied from 0 to 100% rooting and varied with Echeveria cultivar and species, plant growth regulator treatment and rooting temperature.  E. agavoides, and A. critatus, and E. ‘Black Night’ and E. ‘Black Prince’ had the lowest and highest percentage rooting, respectively.  Ethephon promoted rooting of species/cultivars with the lowest percent rooting on cuttings dipped in water and increased the percent survival of rooted cuttings. IBA and NAA showed little or no promotion of rooting, or rooted cutting survival. Cultivars/species differed in the optimal temperatures for leaf cutting rooting; some had an optimal temperature from 10-16C, others from 16-22C (most), and still others from 22-28C. Plant growth regulator application and rooting temperature also affected percent survival of rooted cuttings.