New Flowering Potted Plant Development Progress Reports - June 2000
New Flowering Potted Plant Development
Jeff Kuehny
Louisiana State University
Richard Criley
University of Hawaii
Executive Summary
Development of new potted flower crops is of interest to US greenhouse
operators and consumers and a research priority for scientists. Ornamental
gingers are popular cut flowers and have been promoted as promising potted
flower crops. Characteristics that make them attractive as potted plants to the
floriculture industry are ease of production in the shade house or greenhouse,
unique foliage. production of many flowering stems per pot, long-lasting
colorful bracts, a 90 
100 day production cycle, and few disease or insect
problems. Besides potted plant use, they can be marketed for use in year around
interior landscapes and as either perennials or summer annuals in exterior
landscapes depending upon the climate.
Although limited research has been conducted on ginger, Drs Kuehny and Crilev
have worked with ornamental gingers for several years. Controlling entry into
and termination of dormancy is important in rhizomc production for year around
forcing by growers. Although cut gingers are known to have good postharvest
longevity, effects of various production protocols on growth and development and
appropriate stages of development for shipping of putted gingers are not known.
Research outlined in this proposal includes comparison of tissue-cultured and
field-grown propagules (University itv of Hawaii), determination on of systems
to manipulate rhizome dormancy (University of Hawaii), optimum forcing
conditions (Louisiana State University), and factors that affect postproduction
longevity of the flowering potted plant (Louisiana State University Each
location requires a half-time graduate research assistant to conduct
experiments.
This research will provide commercial field growers and greenhouse operators
with production protocols for several species of gingers as new potted plants.
Producers of propagules will benefit by increasing their product mix and
seasonal marketing period. Greenhouse operators will be able to increase the
assortment of plants they sell to the benefit of the U.S. floral industry and
their consumers. Results of this research will be disseminated through trade
publications and peer-reviewed scientific journals and at grower conferences.
Success of this research will be reflected by the extent to which these plants
are adopted by growers and accepted by the buying public, but the for research
and dissemination time period will extend beyond the 3-year period for which
support is being sought.
Introduction & Literature Review
New potted flower crops are sought by US growers, who also seek the basic
guidelines for their production. Researchers, such as Dr. Jeff Kuchny (Louisiana
State University) and Dr. Richard Criley (University of Hawaii), have grown
gingers and other tropical flowering plants in containers as part of their
research and determined that these plants are easy to grow in shade houses or
greenhouses, have unique foliage and colorful long-lasting inflorescences, a 90
to 100 day production cycle, and new pest problems. Gingers have a range of
uses, both indoors and as patio and garden plants. Tissue culture has increased
propagule availability, but research is needed to program uniform development,
whether from t.c. or field-grown rhizomes.
The name, ginger. embraces many general a in the Zingiberaceae and Costaceae.
They ate herbaceous perennials with short fleshy rhizomes and tuberous roots,
often with a dormancy period. Inflorescence stalks arise from a short pseudostem
or independently from buds on the rhizome. The inflorescence is a compressed
spike of colorful bracts subtending 2 to 7 true flowers. Propagation is by
division of the rhizomes or by micropropagation. Cur curna alismatifolia was
introduced in the late 1980s but did not immediately attract a large grower
interest (5). Recent Thai selections of C. alismatifolia have attractive
inflorescences and offer potential as potted plants or cut flowers (17).
Horticultural descriptions are provided for a kw ornamental cut-flower and
potted species (6, 7, 8,17, 18), but their commercial culture is dispersed in
oft-unavailable literature (2.3,4,9,10,11,15).
Unpublished research by the USDA with Curcuina ‘CMU Pride¬í showed that LD
(HID \VM from 5 am to 8 pm) prolonged vegetative growth while dormancy was
induced in plants receiving natural SD. SD rhizomes were heavier and bore more
fleshy tuberous roots than LD rhizomes. Rhizome clumps with attached tuberous
roots stored at 25 C and forced at 2 5/23 C (D/N) showed little difference in
shoot emergence, while flower development was inconsistent within 10, 12 or 14
hr forcing regimes. C. zeodaria rhizome and tuberous root analyzed for
carbohydrate content in Hawaii showed considerably higher levels of
carbohydrates were in the tuberous roots than in normal (thin) roots or
rhizomes. The tuberous roots wither away during subsequent forcing and are
probably a major source of carbohydrates for vegetative and reproductive
development.
The tuberous root carbohydrate reserves were important in the rate of forcing
C. alismatifolia into flower, as rhizomes without them emerged and
flowered later than if at least 2 tuberous roots were present (12). Tuberous
root number was positively related to inflorescence number and quality.
Maintaining 20-hr LD prolonged flowering while plants growing under 10-hr SD
ceased to produce inflorescence, developed tuberous roots, and entered dormancy
(13). A D/N temperature regime of 26/18 C with LD improved inflorescence stem
length over 23/15 C. Fewer tuberous root-bearing propagules developed under LD
and these required 8 wks more to emerge than did propagules from SD plants,
which emerged after 6 wk dark storage at 30 C. As C. alismatifolia is
reported capable of year around flowering in its native habitat (Zhang et al.,
1995 cited in 13), the potential for manipulating flowering by day length and
temperature control exists Israeli cut flower grower-s have achieved nearly 10
months of flower production by such manipulations. Preliminar research at LSU
indicated that photoperiods of >16 hrs prolonged vegetative growth and 20 hrs
enhanced flower initiation. Plants growing under photoperiods <12 his became
dormant. A Thailand study showed that light intensities >20 lux were
necessary to prevent rhizome dormancy of C. sparganifolia during SD (14).
Increasing light intensities to 95 lux promoted sprouting, plant growth, and
flowering 4 months after planting.
The application of 4 to 8 nig a.i. paclobutrazol (PBZ) to 6-inch pots of Curcuma
failed to reduce finished plant height. Similarly, neither ancymidol nor PBZ
were effective on Alpinia zerurn bet var. variegata (16). Drenches
of 4 to 8 mg PBZ per 8 L pot reduced finished height of Hedychium coronarium
by 30% (1). Foliar applications of GA significantly increased the number of
days to bloom and flower scape length of tissue-cultured C. gracilliina plants,
while Bonzi drenches had little effect on plant height. GA soaks of rhizomes of C.
alismatifolia did not increase flower number, and drenches of PBZ when
shoots were 10 cm tall did not affect finished plant height (Kuehny, unpublished
data). Lateral shoot number and rhizome weight of tissue cultured Globba
winitii plants sprayed with benzyladenine were not affected (Kuehny,
unpublished data).
Postproduction studies indicate that C. gracillima has an acceptable
postproduction longevity of approximately 2.5 weeks, C. pariviflora of
3.7 weeks, C. alismailfolia of 4.7 weeks, and Siphonochilus decora of
4 weeks (Kuehny, unpublished data).
Objectives and Anticipated Benefits
1. To determine the best method of producing ornamental ginger as a
flowering pot plant by comparing growth and development of tissue-cultured and
field-grown rhizome propagules.
We propose comparison of tissue culture and rhizome propagules so that
plant-to-flower time frame will be optimized. This information will also help
determine rate of rhizome development in field production, the best type and
age of ginger propagule for pot plant production, and proper propagule size to
specific pot size.
2. To develop systems to manipulate dormancy in rhizomes of gingers in
order to extend the seasonal availability.
Information obtained by manipulation of photoperiod, length of rhizome
storage, rhizome storage temperature and use of plant growth regulators will
enable field growers to control entry into and termination of dormancy in
order to produce rhizomes for year around forcing by greenhouse growers.
3. To determine the optimum forcing conditions for gingers.
The optimum light intensity, day length and air temperature for forcing
ginger will be elucidated so that greenhouse growers can produce a marketable
pot plant to increase their product availability, product assortment and
production efficiency.
4. To determine the influence of growth regulators in the production of
ginger species as flowering potted plants.
The testing of growth retardants to help regulate plant growth for optimum
size will help growers produce a more marketable plant. Increasing
postproduction longevity by use of cytokinins will also help prolong a
naturally long shelf life.
5. To characterize the postproduction life of gingers and evaluate
preproduction factors that may extend the postproduction longevity of the
flowering potted plant.
One of the most important factors for the viability of any new potted plant
is post-production longevity. The best production practices to ensure a long
postproduction longevity will be determined to enhance consumer appeal and
marketability.
Materials & Methods
The ginger species to be used in these experiments are C‘urcuma
alismaqfolia, Curcurna cordata, Curcuma roscoeana, Globba winnitii and Siphonochilus
decora. The following experiments arc outlined by objective.
Objective 1:
Plant quality and finishing time of tissue-cultured plants will be compared
with the same species of plants grown from field grown rhizomes produced at
the University of Hawaii. The rhizomes will be grown from the same source of
tissue cultured plants that are currently being grown to produce sizable
rhizomes for this experiment. One set of tissue cultured plants will be
planted in the field at the University of Hawaii in February, 2000 and another
set planted in July, 2000 to provide two different sizes (grades) of ’rhizomes.
This experiment w:ll be a randomized complete block design with 4 blocks and 3
treatments (tissue cultured plants, rhizome set 1, rhizome set 2). The
evaluation will include measurements of starting plant mass, number of growing
points produced, number of inflorescence stalks produced, plant size (height
and width), days to emergence, days from emergence to flower, and useful
postproduction longevity as outlined in objective 5.Timeframe: Year 1 (spring 2000 to summer 2001).
Sites: Hawaii - field rhizome production. Louisiana - forcing,
obtaining production and postproduction data and plant quality evaluations.
Objective 2:
Extended photoperiods will be imposed on vegetative plants in field
production to prevent dormancy and extend the period during which
inflorescence and or vegetative and rhizome growth can be produced. At a
specified time field-grown plants will be subjected to short day conditions
during the normal growing season to induce early dormancy. These rhizomes will
be stored for 4, 12, 20 or 28 weeks at 15, 20 or 25 C to determine the storage
longevity of the rhizomes, the effect of temperature on the longevity of
rhizomes and consequent shoot emergence, growth and flowering, and whether a
dormant period and duration of the dormant period is necessary for
inflorescence production. Growth regulators known to break dormancy, such as
ethephon, gibberellins, and cytokinins will be applied to rhizomes at 5
stages: 1) immediately after digging, 2) after 4 weeks of storage, 3) after 12
weeks of storage, 4) after 20 weeks of storage, and 5) after 28 weeks
of storage. This will help to determine PGR effectiveness in stimulating bud
break and their influence upon inflorescence production. The types of data to
be taken include: carbohydrate accumulation in the rhizomes and their
relationships to dormancy, emergence and flowering, time frames from
initiation of storage to emergence, numbers of’ shoots, percentage of shoots
that develop inflorescence, time frame from emergence to anthesis, quality of
finished product, effects of storage and PGRs on postproduction longevity as
outlined in objective 5.Timeframe: Year 1 & 2 (fall 2001 through fall 2002).
Site: Hawaii Field production of rhizornes will begin in fall 2001,
storage and PGR experiments will be conducted. Louisiana - greenhouse
production of rhizomes from the outlined experiment in Hawaii.
Objective 3:
Optimum rhizome production and storage methods determined in Obj. 2 will be
used to produce rhizomes for this set of experiments. Potted gingers will be
subjected to factorial experiments in which the light intensity, day length,
and temperature environments provide a range of commercially feasible forcing
conditions. Treatments will include: light intensities of full, 75% or 50% of
ambient; extended day lengths of 8. 14 or 20 hours; day/night temperatures of
25/20 C, 3 0/25 C, or 3 5/30 C. The data to be taken include days to
emergence, days from emergence to inflorescence, and postproduction longevity,
plant height, diameter, shoot and inflorescence number, and post-production
longevity as outlined in objective 5.Timeframe: Years 2 & 3 (summer/fall 2002 Hawaii, spring/summer
2003 Louisiana).Site: Hawaii Production of rhizomes for forcing in Louisiana.
Louisiana - Forcing of rhizomes and conducting outlined experiments.
Objective 4:
A randomized complete block design will be used to test the effect of 0,
10, 20 and 30 mg a.i. Bonzi (paclobutrazol)/ pot on plant quality,
floriferousness; possible adverse effects of the growth retardants will be
determined. The optimum forcing conditions determined from objective 3 will be
used for production of plants in this experiment. Ginger rhizomes from Hawaii
will be forces in greenhouses at LSU. A randomized complete block design will
be used to test the effect of N-6-BAP sprayed when the infloresccnce of potted
gingers is 14 to 1/3 open. The plants will be placed in a postproduction room
for evaluation. Data taken for the postproduction study will include those
outlined in objective 1.Timeframe: Years 1 & 2 (summer/fall 2001 Hawaii, spring 2002
Louisiana).Site: Hawaii - rhizome production. Louisiana greenhouse production
in spring 2002.
Objective 5:
When the inflorescence of potted gingers is 1/4 to 1/3 open, plants will be
removed from the greenhouse production environment and placed in interior
conditions The interior environment for postproduction will be held at 21±3C,
with an irradiance of 30 umol 2 s* Postproduction life will end at flower
abscission. Flower quality ratings will be based on a scale of 1, 2, or 3(1 =
best and 3 = worst I of visual plant quality will he based on a scale from 1
to 10; 10 = excellent, 8 = good, 6 = regular, 4 poor, 2 = very poor, 0 = dead
plant. This scale is based on leaf abscising/yeIlowing, flower form/color.
flower abscising, flower development, flower distribution, stem and leaf
distribution. Flower height will be measured weekly through the postproduction
phase. All measurements will be taken before plants arc moved to the interior
environment and then weekly thereafterTimeframe: Years 1, 2, and 3 on plants produced in experiments from
objectives 1, 2, 3 and 4.Site: Hawaii - Production of rhizomes for forcing in greenhouse.
Louisiana - Forcing of rhizomes and conducting experiments.
Research conducted at LSU focuses primarily on the forcing, development of
greenhouse production protocols, and postproduction evaluations. Research
conducted at UH focuses upon production of rhizomnes for use in Louisiana and
Hawaii, dormancy and dormancy-breaking characteristics, and effects of plant
growth regulators on rhizome quality and forcing characteristics. LSU and UH
each require a half-time research assistant to conduct the experiments. analyze
plant tissues, and analyze data.
