Mara Grossman will present a seminar on her PhD dissertation research “Controlling Growth in Echinacea Hybrids” (nursery/greenhouse container production) in advance of her defense: Friday, Feb. 10th at 1:00 p.m., 403 Saunders. Seminar is open to faculty, staff, grad students, and undergrad students.
New hybrid Echinacea cultivars, based on crosses of Echinacea purpurea (L.) Moench with several other Echinacea species, have generated interest and excitement in the marketplace due to novel flower colors and forms. However, these cultivars vary significantly in their growth habits and requirements from the species. We examined factors in the production of Echinacea hybrid cultivars to provide guidance to growers. Foliar sprays 600 mg·L-1 benzyladenine (BA) increased branches in Echinacea cultivars while 400 mg·L-1 dikegulac sodium or 500 mg·L-1 ethephon did not improve branching. Of several height control PGRs applied to E. ‘Marmalade,’ only two applications of 5000 mg·L-1 daminozide reduced height although flowering was also reduced. Echinacea ‘Harvest Moon,’ had decreased height in response to all of the PGRs applied, with the best results seen in plants treated with foliar sprays of uniconazole (1 application of 30 mg·L-1 or two applications of 15 mg·L-1 ), two applications of 5000 mg·L-1 daminozide, or 4 mg·L-1 paclobutrazol applied once as a drench. Supplying N at 150 mg·l-1 during the growing season provided Echinacea cultivars adequate nutrition and maximized number of branches, flowers and shoot dry weight. In overwintering, fertilization treatments that resulted in low substrate electrical conductivity going into dormancy resulted in the highest survival rates of Echinacea cultivars. As a monitoring tool, SPAD measurements were not successful in predicting tissue N levels in Echinacea hybrids. Twenty-one hybrid cultivars acquired as stage 3 tissue culture plantlets were grown under one of three photoperiods (10-hour, 16-hour, and 24-hour) for ten weeks before being transplanted to larger containers and grown under natural daylength until flowering. Providing Echinacea hybrid cultivars with a 16-hour photoperiod during liner production resulted in plants which flowered soonest without negative effects on growth. The need for height control PGRs varied by cultivar; however, overall height control PGRs reduced flower stalk height and increased market rating.