Evaluating the influence of benzyladenine on branching of echinacea cultivars

Evaluating the Influence of Benzyladenine on Branching of
Echinacea Cultivars
Sonali Padhye and Jude Groninger
Department of Environmental Horticulture, University of Florida, West Florida Research and Education Center (WFREC)
Introduction
Echinacea cultivars are one of the top 10 herbaceous perennials grown and sold in the United States.
The recent introduction of Echinacea hybrids in new attractive colors has boosted the consumer
interest and sales. Commercial growers producing finished Echinacea for spring sales are interested
in improving its quality by manipulating production practices to obtain aesthetically appealing plants
that are well-branched and compact in height. Young plant producers are also interested in
increasing branching of Echinacea cultivars to maximize the number of cuttings obtained from
stockplants.
Benzyladenine (Configure, Fine Americas) foliar sprays have been reported to promote branching of
select Echinacea cultivars. Most of these studies have been performed on seed-propagated cultivars
with an exception of a few with the new hybrids. The seed-propagated Echinacea cultivars are
typically more vigorous and branch more readily compared with the new inter-specific hybrids. A
commercial young plant producer of Echinacea, Emerald Coast Growers has reported that Configure
sprays did not increase branching of several Echinacea hybrids when stage-3 tissue culture plants
were planted and sprayed in the early spring of 2008. The influence of Configure sprays on
branching of the new Echinacea hybrids needs further investigation. It has been reported that the
timing of Configure application during the development of Echinacea may also influence the
branching and should be further studied.
The flowering of Echinacea in response to photoperiod has been well-documented for seed
propagated cultivars such as ‘Bravado’ and ‘Magnus’. Under 10- or 12-hour photoperiods, these
cultivars rosette, and they flower rapidly under a 14-hour photoperiod or when plants are grown
under short-days (10-hour photoperiod), followed by long-days (24-hour photoperiod) (short-long-
day treatment). When grown under a 16-hour photoperiod or night interruption treatment, flowering
is delayed compared with that under a 14-hour photoperiod or short-long-day treatment. Based on
these photoperiodic responses, we postulate that photoperiod may be a regulatory factor during the
development of lateral branches of Echinacea and warrants further studies. The objectives of these
experiments are to: 1) quantify the influence of Configure sprays on branching of select new
Echinacea hybrids, 2) determine the influence of timing of Configure application on branching of
Echinacea cultivars, and 3) investigate the effect of photoperiod on branching of Echinacea cultivars
sprayed with Configure.
Materials and Methods
Experiment-I
Objective: Quantifying the influence of Configure sprays on branching of select new Echinacea
hybrids and determining the influence of Configure application timing on branching of these
cultivars.
Protocol: Young plants of Echinacea ‘Harvest Moon’ or ‘Twilight’ (reportedly most difficult to
branch), ‘After Midnight’ (reportedly average branching), ‘Sunrise’ or ‘Summer Sky’ (reportedly
easier to branch) (stage 3 tissue cultured) and ‘Magnus’ (seed propagated cultivar for comparison)
will be obtained from Emerald Coast Growers. Plants will be transplanted in a peat-based medium
and grown in the polycarbonate greenhouse at WFREC, Milton under a 16-hour photoperiod
provided as a day-extension using high-pressure sodium lamps.
Half the Echinacea plants of each cultivar will be sprayed with Configure at transplant and the
remaining half will be allowed to grow until the roots circle the pots (~3 weeks) and then sprayed
with Configure. Configure will be applied as a single foliar spray (volume of 2 quarts/100 ft2, with
Capsil as a surfactant) at 300, 600, or 900 ppm rates. An additional treatment will consist of 600 ppm
Configure at the same spray volume with Penta-Bark as a surfactant added at the labeled rate. A non-
sprayed control will be maintained. Ten plants will be subjected to each treatment combination. The
fertility and pest management will be as per standard protocols developed at WFREC.
The number of lateral branches and plant height (from surface of the medium to the apical meristem)
will be recorded at least two times when differences in branch numbers are observed (possibly 3 and
6 weeks after Configure application). Additionally, at first open flower, data collection will include
date, number of branches, number of flower buds, and plant height.
Treatments and Plant Numbers:
2 application times + 3 chemical rates + 1 Penta-Bark treatment + 1 non-sprayed control = 9
treatments per cultivar
Total = 9 treatments x 10 plants/treatment = 90 plants per cultivar (360 plants total)
Estimated Start Date: June 2008
Experiment-II
Objective: Investigating the effect of photoperiod on branching of Echinacea cultivars following
Configure sprays.
Method: Based on the results of experiment-I, appropriate developmental stage, Configure spray rate
and surfactant to promoting branching of Echinacea cultivars will be selected. Young plants received
from Emerald Coast Growers will be transplanted and sprayed with Configure. Plants will be grown
in polycarbonate greenhouse at WFREC under a 9- or 16-hour photoperiod. Data collection will be
similar to experiment-I.
Treatments and Plant Numbers:
2 photoperiods + 2 treatments (Configure treatment + non-sprayed control) = 4 treatments per
cultivar
Total = 4 treatments x 10 plants/treatment = 40 plants per cultivar (160 plants total)
Estimated Start Date: About 2-4 weeks after the end of experiment-I.
Photographs will be taken to document plant responses in both the experiments.
Budget: $6,000

Source: http://www.fine-americas.com/_Attachments/Resources/885_S4.pdf