Production and Ethylene Strategies to Increase Longevity of Flowering Potted Plants
Production
and
Ethylene Strategies to Increase
Longevity of Flowering Potted Plants
Terril A. Nell Ria T Leonard, James E. Barrett and David G.
Clark
Department of Environmental Horticulture
University of Florida, Gainesville, FL 32611-0670
1. EXECUTIVE SUMMARY
Flowering potted plant quality
and postproduction life continues to be a significant issue for growers,
wholesalers and retailers. Over the past decade, considerable work has been
conducted with poinsettias, chrysanthemums, azaleas and other crops. The
research on poinsettias and chrysanthemums has led to significant improvements
in varieties, handling procedures and increased flowering potted plant life.
Leaf yellowing and bract edge burn in poinsettias and leaf yellowing and short
longevity of chrysanthemums are minor problems today as a result of research in
this program. However, in our studies and studies in Europe, all postharvest
longevity research has been conducted without exposure to ethylene. All of this
research was conducted to mimic traditional markets and distribution chains ¬ó
grower to wholesaler to retailer to consumer. But, the market has changed! Many
of the flowering potted plants sold in the U.S. today are marketed through
supermarkets and “Big Box” stores where poor handling is common and
ethylene is prevalent in distribution centers and retail display areas. It
appears that the primary ethylene problems are occurring during shipping and in
distribution centers. The goals and crops for this project are based on personal
conversations with flowering potted plant growers throughout the U.S. We will
expand our research on flowering potted plants to include ethylene treatments
and to utilize the “known” relationships between cultural factors and
variety to longevity of minor, but significant crops in the U.S. Specifically,
we will study the relationship of production practices, varieties and ethylene,
including the use of anti-ethylene chemicals, as opportunities to enhance the
quality of flowering potted plants. As a result of the studies to be conducted,
we will be able to advise the industry in
variety selection, production practices and shipping’ storage conditions for
approximately 6 economically important crops. Additional crops can be added
during this project if other postproduction problems are identified by AFE or
members of the industry.
2. INTRODUCTION AND LITERATURE REVIEW
We live in a global society. There is no place in
the world that cannot be physically reached within 24 hours, and the internet
has made international communication a snap. Borders exist. but satellites that
circle the globe and cables that snake across ocean floors bounce and ferry
signals that blur the lines of continent, country, and state. In an
international marketplace, where purchasing chocolates from France, pastry from
the Mideast and seeds from the Southwest is an easy electronic transaction done
in the privacy of your own home, how do growers compete to earn a portion of
consumers’ discretionary income? The answer is simple: Deliver
quality flowers.
Specific cultural, transportation and interior
conditions have been published for a variety of flowering potted plants (Nell,
1993; Nell and Reid, 2000)) and grades and standards have been published by SAF
and FMA. Leaf yellowing and bract edge burn in poinsettias and leaf yellowing
and short longevity of chrysanthemums are minor problems today as a result of
research conducted in this program and communicated to breeders and growers
(Nell 1993). Most of the research results reflected in these publications were
conducted in an ethylene-free environment and without exposure to ethylene. In
the past, ethylene research demonstrated the plant/flower symptoms resulting
from ethylene exposure but did not identify solutions for the industry (Serek
and Reid, 2000). Some exceptions do exist, as in research demonstrating
potential benefits from treatment of flowers with Ethylbloc on a limited number
(one variety used) of potted roses (Serek et.al. 1994).
The problem is that Ethylbloc
does not provide protection for long periods on some crops (Reid et.al. 1999).
Preliminary research in our laboratory has demonstrated that Ethylbloc does not
provide protection from ethylene after 6 days on potted roses and less than 2
days for elatior begonias. Only one variety of each crop was used in these
limited trials.
As we explore solutions to
increased longevity for other flowering potted plants, we must draw upon the
“knowledge” acquired on poinsettias, chrysanthemums and azaleas in
identifying techniques to increase plant longevity. The primary factors which
have been shown to affect longevity and quality are: genetic influence (cultivar),
nutrition, and postproduction handling (Nell et.al. 1997). The importance of
these factors in producing and maintaining quality and longevity is documented
in the literature, thus, only a brief summary of each area is provided.
Genetic influence:
Differences
in longevity of flowering potted plant cultivars range from delayed senescence
(increased longevity), increased tolerances to low irradiance levels and
sensitivity to ethylene (Nell et.al. 1997; Mueller et.aI., 1998). The genetic
engineering program led by Dave Clark at the University of Florida has
demonstrated the significance variety and genetics can have on longevity.
Differences in longevity of chrysanthemum cultivars and sensitivity of
poinsettia cultivars to leaf yellowing and bract edge burn have been documented
(Nell, 1993). Research conducted in Denmark in the late 1980’s (unpublished)
demonstrated that kalanchoe varieties range from extremely sensitive to tolerant
to ethylene. Knowing the ethylene sensitivity of current flowering potted plant
varieties could dramatically change variety selection for the grower and lead to
plants which survive exposure to transport and retail conditions ¬ó without the
use of chemicals!
Nutrition:
Nutrition
programs may have more impact on flowering potted plant longevity and quality
than any production factor other than cultivar. Fertilizer concentration,
fertilizer source and fertilizer type influence plant performance indoors. High
fertilizer reduced azalea and chrysanthemum longevity and increased leaf drop,
bract edge bum and bract fading in poinsettias (Yell et al., 1986, 1989; Scott
et al., 1984). It is clear that plants grown with high ammonium levels and
excessive fertilizer levels are more sensitive to transport conditions and last
for shorter periods indoors. Research has not been conducted to determine if
fertilizer type or concentration affects the sensitivity to ethylene.
Postproduction Handling:
Proper
conditions during transport, distribution and retail/consumer display will
maintain plant quality and maximize longevity for the consumer. Adverse
transport conditions have been shown to induce bud drop in hibiscus (Nell and
Barrett, 1984), leaf drop in poinsettias (Nell and Barrett, 1986) and reduce
flower opening of miniature potted roses (Nell and Noordegra??f, 1991). High
shipping temperatures increase the sensitivity of flowering plants and fresh cut
flowers to ethylene. Interestingly, reducing fertilizer on chrysanthemums
increased tolerance to adverse shipping conditions. There are no data relating
cultural practices (fertilizer, watering and stage of flower opening at
marketing) to increased tolerance of plants to ethylene but this aspect of
postproduction longevity should be investigated.
3. OBJECTIVES
1) To identify the ethylene
sensitivity of potted rose, elatior begonia and ornamental pepper cultivars.2) To evaluate the value of
anti-ethylene compounds as a means of minimizing ethylene damage to flowering
potted plants.
3) To determine the duration of effectiveness
of anti-ethylene compounds on flowering potted plants.4) To identify the value of selected cultural
practices to extending the longevity of difficult to handle flowering potted
plants.
4. MATERIALS AND METHODS
Ethylene, Ethyibloc and Silver Thiosulfate (STS)
treatments:
A flow-through air system has been built in one
of our interior rooms for the treatment of flowering potted plants with
ethylene, ethylbloc or other anti-ethylene compounds. The system includes a
combination of brass mixing valves and pressure gauges that will allow exact
concentrations of gaseous chemicals (ethylene, ethylbloc etc.) to flow through a
series of clear glass aquariums. Flowering potted plants will be placed into
each aquarium and sealed (airtight) prior to the injection of the gases. This
system allows us to maintain a constant flow of the desired ethylene through
each aquarium, thus avoiding the buildup of humidity or other gases. Plants will
be treated with EthylBloc in these chambers prior to treatment with ethylene.
Silver thiosulfate will be applied to all plants as a liquid spray. The flow
through air system provides the opportunity to treat flowering potted plants
with 1) different gas concentrations; 2) expose plants to the gases for various
periods; 3) evaluate different varieties and 4) evaluate sensitivity of various
stages of floral development. During the course of this project, flowering
potted plants will be evaluated for each of these criteria concentration, time
of exposure, variety sensitivity and stage of development.
The studies to be conducted are listed below. Our
plan will be to combine the types of studies listed below so that we
systemtically and thoroughly evaluate one type of flowering potted
plant before beginning research on the next crop. We will evaluate the crops in
the following order during this project: roses, kalanchoes, elatior begonia and
ornamental pepper. By thoroughly evaluating each crop before initiating studies
on the next crop, we will be able to share information on ethylene injury and
possible solutions with the industry simultaneously. Otherwise, we would spend
over a yea:’ identifying the ethylene problems on these crops but would not be
able to provide methods to eliminate or reduce the ethylene damage.
Study 1: Effect of ethylene on interior
performance of cultvars of potted roses, kalanchoes, ornamental pepper and
elatior begonia.
The treatments in this study will be 1) cultivars
of potted roses, kalanchoes, elatior begonia and ornamental pepper and 2)
ethylene or no ethylene. Each flowering potted plant variety will be placed into
the treatment chambers and exposed to 1 ppm ethylene for 24 hours. A 0 ppm
ethylene (air) will be used as a control. After the ethylene treatment, the
plants will be moved to our interior rooms for postproduction evaluations. All
possible symptoms of ethylene injury (bud drop, bud yellowing, failure of
flowers to open, leaf yellowing and inrolling of flowers) will be monitored and
recorded on every treated plant. For each of the flowering potted plants, we
will evaluate at least 12 cultivars, except for ornamental pepper where only
limited numbers of varieties arc on the market.
Study 2: Effect of anti-ethylene compounds on
flowering potted plants.
Three treatments will be used in this study: 1)
no anti-ethylene treatment; 2) Ethylbloc; and 3) STS. The Ethylbloc treatment
will be made in the treatment chambers but the flow through system will not be
used Ethylbloc will be placed into chambers using manufacturers recommendations
and for the recommended exposure time. This treatment procedure will simulate
the practice used by the industry.
Following the Ethvlbloc and STS treatments,
plants will be placed into the treatment chambers and exposed to 1 ppm ethylene
for 24 hours. Following the ethylene treatment, flowers will be moved to our
interior rooms for postproduction evaluation. All possible injury symptoms will
be monitored and recorded for each plant.
Study 3; How long does EthylBioc and STS
protect plants from ethylene?
The most ethylene sensitive varieties of roses,
kalanchoes and elatior begonias will be used for this study. We plan to use 2-3
varieties of each these plant types in this study. Plants will be treated with
EthylBloc, STS and ethylene as outlined in Study 2 except for the timing of the
ethylene treatment. The treatments in this study will be 1) No ethylene
treatment; 2) EthylBloc or STS; and 3) Time of exposure to ethylene. Following
Ethylbloc and/or STS treatment, plants will be placed into our interior rooms.
Then, plants will be returned to the ethylene treatment chambers and treated
with 1 ppm ethylene at 0,2,4 and 6 days to determine the effective period of
protection these anti-ethylene compounds are providing to each plant type. The 0
day treatment will occur immediately following the EthylBloc and STS treatments.
Once the ethylene treatment is complete, the plants will be returned to our
interior rooms for evaluation. Ethylene injury symptoms and longevity will be
monitored and recorded for each plant.
Study 4: Evaluation of “Known”
postproduction practices on alternative crops
Postproduction longevity is an issue on a wide
variety of flowering potted plants. In these studies,
we will explore the possibility of applying proven postproduction practices,
such as fertilizer practices, wetting agents, calcium sprays etc. to improve the
interior performance of hydrangea, cyclamen and other crops. Specifically, we
will investigate the value of’ fertilizer rate and fertilizer termination as a
means of extending longevity, use of wetting agents to reduce water demand
indoors of such crops as hydrangea and calcium sprays to reduce the
postproduction problems associated with botrytis and powdery mildew. The crops
used in these studies will include hvdrangea. cyclamen, gerbera and potted rose.
5. LITERATURE CITED
Muller R., A. Anderson and NI. Serek. 1998.
Difference in display life of miniature potted roses, Scientia Horticulturae
76:59¬ó71.
Nell, TA. 1993. Flowering potted plants:
prolonging shelf life: postproduction care and handling. Ball Publishing,
Batavia, IL.
Nell, T.A. and J.E. Barrett. 1984. Effect of
simulated shipping temperature and duration on prefinished flowering hibiscus.
1984 Proc. Fla. State Hort. Soc. 97:278-279.
Nell, T.A. and J.E. Barrett. 1986. Growth and
incidence of bract necrosis in ‘Gutbier V-14 Glory’ poinsettia. J. Amer.
Soc. Hort. Sci. 111:266-269.
Nell. T.A. and J. E. Barrett. 1986. Influence of
simulated shipping on the interior performance of poinsettias. HortScience. 21:3
10-3 12.
Nell, l.A., R.T. Leonard and J.E. Barrett. 1989.
Fertilizer termination influences postharvest performance of pot chrysanthemum.
HortScience 24:996-998.
Nell, TA.. J.e. Barrett and R. T. Leonard. 1997.
Production factors affecting Postproduction quality of flowering potted plants.
HortScience 32:S17-818.
Nell, T.A. and M.S. Reid. 2001. Flower and Plant
Care: The 21 st Century Approach. 212 pages. Society of American Florists.
Alexandria, VA.
Nell, T. A. and C. V. Noordegraaf 1991. Simulated
transport and postproduction irradiance influence postproduction performance of
potted roses. HortScience 26:40 1-1404.
Reid, Ni., L. Dodge, F. Celikel and R. Valle.
1999. 1-MCP, a breakthrough in ethylene protection. ‘Floriculture
International. November 1999.
Scott, L.F., T.M. Blessington and J.A. Price.
1984. Influence of controlled release fertilizers, storage duration and light
source on postharvest quality of poinsettias. HortScience 19:111-112.
Serek, M. and M.S. Reid. 2000. Ethylene and
postharvest performance of kalanchoe. Postharvest Biology and Technology. 18:
43-48
Serek, Ni., E. Sisler and MS. Reid. 1994. A
volatile ethylene inhibitor improves the postharvest life of potted roses.
J.Amer. Soc. Hort. Sci. 119:572-577.
