Source: MICHIGAN STATE UNIV submitted to
ENVIRONMENTAL AND CULTURAL STRATEGIES TO CONTROL GROWTH AND DEVELOPMENT OF FLORICULTURE CROPS
 
PROJECT DIRECTOR: Runkle, E. Cameron, A. Harsh, S. Warner, R. Both, A. J. Erwin, J. Fisher, P. Frantz, J.
 
PERFORMING ORGANIZATION
HORTICULTURE
MICHIGAN STATE UNIV
EAST LANSING,MI 48824
 
NON TECHNICAL SUMMARY: Understanding ideal growing conditions for floriculture crops helps the greenhouse industry to become more efficient and profitable. With the recent surge in heating costs, there is increased need to produce greenhouse crops more efficiently. In addition, growers are always seeking new, profitable crops to produce, such as potted flowering orchids. This project focuses on improving production strategies of bedding plants, herbaceous perennials, propagative materials, and flowering potted orchids. The primary research goal is to improve our understanding of how light and temperature can be managed to produce high-quality greenhouse crops in an energy-efficient manner. Research-based information generated from this project will be disseminated to greenhouse growers in Michigan and beyond.
 
OBJECTIVES: Objective 1. To determine environmental and cultural strategies to stimulate branching and flowering of potted orchid hybrids, including Phalaenopsis, Miltoniopsis, and Zygopetalum. Based on our recent research, temperature is the primary environmental factor that controls flowering of orchid hybrids. Therefore, studies will focus on low temperature flower induction and cultural strategies to improve potted orchid flowering predictability and quality. Objective 2. To quantify effects of photoperiod and DLI on plant development and quality of popular annual and herbaceous perennial species during the seedling stage (for seed-propagated plants) and rooting stage (for plants propagated by stem cuttings) and from transplant to flowering. In some instances, the interaction of greenhouse temperature and DLI will also be studied. Objective 3. To determine rates of flower development of popular bedding plant species to improve the accuracy of predicting flowering responses to temperature. We will collaborate with colleagues at the University of Minnesota and the University of Florida to develop decision-support spreadsheets that could improve commercial greenhouse crop scheduling. In addition, this information will be integrated with models that predict greenhouse energy consumption so that growers can identify the most energy-efficient production temperatures given their greenhouse location and characteristics.
 
APPROACH: Objective 1. Potted orchid plants will be grown in various greenhouse compartments with temperature setpoints of 11 to 29 C. Most temperature treatments will be a constant temperature, while some treatments will have a warmer day than night temperature (e.g., 20 C day/ 14 C night). Light will be modulated to ensure that light does not confound temperature responses. We will use established plant culture guidelines for potted orchids (Lopez and Runkle, 2006). Additional experiments will be performed to determine if different plant growth regulators influence branching of vegetative shoots, stimulate flower induction, and inflorescence height. Additional studies with media components and fertility concentrations will be performed when merited. Objective 2. To test the effect of photoperiod on flowering of herbaceous perennials and annuals, plants will be grown at 20 C and placed under photoperiods that range from 9 hours to 24 hours but with a similar DLI. An additional treatment will be a 16-hour photoperiod without blackcloth so that plants receive a long day with additional photosynthetic light. To test the effect of DLI on seedling development and quality, and propagation time of nonrooted cuttings, plants will be provided with different DLIs that range from 2 to 15 mol/m-2d-1. The photoperiod will be a constant 16 hours and temperature will be maintained at 20 or 23 C, depending on the species. Objective 3. We will obtain numerous popular bedding plant species for investigation based on sales volume and the lack of published information on controlled temperature responses. We have chosen to focus on seed-propagated crops; John Erwin at the Univ. of Minnesota will perform similar temperature experiments on several vegetatively propagated annuals. We will obtain young bedding plant seedlings growing in 288-cell plug trays and raise them in refrigerated growth chambers at 20 C with an average DLI of 8 mol/m-2d-1 and a 16-hour photoperiod. Seedlings will be transplanted into 10-cm containers and grown in greenhouses at four different temperatures and two DLIs. "Cold-tolerant" crops will be grown at constant temperature setpoints of 14, 17, 20, and 23 C under a 16-hour photoperiod; "cold-sensitive" crops will be grown at constant setpoints of 17, 20, 23, and 26 C. At each temperature, plants will be grown under two different DLIs. We will model the effect of temperature on crop development for each species. The developmental models will be integrated into a computer software program, Virtual Grower (developed by the USDA-ARS in Toledo, OH). The outcomes of the model will predict crop timing and energy consumption based on user-defined inputs such as growing temperature, greenhouse location and structure, time of year, fuel type, fuel cost, etc. The plant and energy models will be validated by growing crops in greenhouse compartments with different temperature setpoints and at various times of the year.
 
CRIS NUMBER: 0192266 SUBFILE: CRIS
PROJECT NUMBER: MICL02021 SPONSOR AGENCY: NIFA
PROJECT TYPE: HATCH PROJECT STATUS: REVISED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: May 1, 2007 TERMINATION DATE: Apr 30, 2012

GRANT PROGRAM: (N/A)
GRANT PROGRAM AREA: (N/A)

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
204212010202.210%
204212210202.210%
204212310202.210%
204212310502.210%
205212010202.210%
205212210202.210%
205212310202.210%
205212310502.210%
404212010502.110%
404212310502.110%

CLASSIFICATION HEADINGS
KA205 - Plant Management Systems
KA404 - Instrumentation and Control Systems
KA204 - Plant Product Quality and Utility (Preharvest)
S2120 - Herbaceous perennials and decorative greens
S2123 - Bedding/garden plants
S2122 - Potted plants
F1020 - Physiology
F1050 - Developmental biology
G2.2 - Increase Efficiency of Production and Marketing Systems
G2.1 - Expand Domestic Market Opportunities


RESEARCH EFFORT CATEGORIES
BASIC 15%
APPLIED 60%
DEVELOPMENTAL 25%

KEYWORDS: greenhouse; energy; floriculture; plants; flowers; production; efficiency; orchids; perennials; annuals; light; temperature

PROGRESS: Jan 1, 2011 TO Dec 31, 2011
OUTPUTS: Project #1. Bedding plants are grown in greenhouses during some of the coldest months of the year. Rising energy costs have prompted some growers to lower their greenhouse temperatures in an attempt to save on fuel costs for heating. However, plants develop slower at a lower temperature and thus, the production period is lengthened. Energy-efficient production requires species-specific information on how temperature influences flowering time and plant quality. Nineteen popular bedding plant crops, including Antirrhinum, Calendula, Diascia, Gomphrena, Gerbera, Impatiens, Heliotropium, Matthiola, Nicotiana, Nemesia, Nierembergia, Osteospermum, Pelargonium, Petunia, Tagetes, and Torenia, were grown in five glass greenhouse compartments maintained at constant air temperature setpoints of 14, 17, 20, 23 or 26 C. (57 to 79 F). The 16-hour photoperiod consisted of the natural photoperiod with supplemental high-pressure sodium lighting from 6am to 10pm. The photosynthetic daily light integral during this experiment varied from 8 to 26 mol per square meter and day. Days to flower from transplant, number of nodes below first open flower, and plant quality parameters such as flower or inflorescence number, and plant height were measured when the first flower opened on each plant. Project #2. Each year, at least a few hundred new ornamental plant varieties are introduced to the floriculture industry by plant breeders. Some of these introductions are herbaceous perennial crops with improved flowering characteristics (for the consumer) and earlier, more uniform flowering (for the producer). We performed experiments with a variety of new perennial plant introductions focused on determining flowering responses to photoperiod and vernalization. Propagules were exposed to different durations (typically from 0 to 10 weeks) of cold treatment at 5 C (41 F) and then grown in a controlled greenhouse environment at 20 C (68 F) under a 9-hour truncated photoperiod (short day), a short day with 7 hours of day-extension lighting from incandescent lamps (long day), or a 16-hour day consisting of the natural photoperiod with supplemental lighting from high-pressure sodium lamps. Information from these and other floriculture research projects was provided to growers throughout Michigan, the US, and in other countries at grower meetings and scientific conferences. For example, presentations were delivered in California, Hawaii, Iowa, Michigan, Ohio, and Pennsylvania in 2011. Articles were also published online and in trade magazines; visit the MSU Floriculture website, http://www.flor.hrt.msu.edu, for reprints and more information. PARTICIPANTS: Tasneem Vaid, M.S. graduate student, performed experiments; Mike Olrich, Research Technician at MSU., assisted with creating and maintaining experimental conditions; Catherine Whitman, research technician at MSU, performed experiments and assisted with writing reports; Jonathan Frantz, USDA-ARS, provided input in the experiments and developed software used to calculate greenhouse heating costs. TARGET AUDIENCES: Commercial growers of ornamental crops, especially for greenhouse producers of floriculture crops. Although the target audience is growers in Michigan and the Midwest, a substantial amount of the information has been communicated to, and can be potentially implemented by, specialty crop growers throughout the United States. PROJECT MODIFICATIONS: Not relevant to this project.

IMPACT: 2011-01-01 TO 2011-12-31 Project #1. As temperature increased from 14 to 26 C (57 to 79 F), time to flower decreased for all crops studied except Impatiens. Of the 19 crops studied, plant quality parameters increased as temperature decreased for a majority of the species. Linear regression analysis was performed on the flowering rate (reciprocal of days to flower) data to estimate the base temperature (Tmin) for each species, which is the temperature at which the flowering rate is zero. Tmin ranged from -2.8 C (27 F) in Calendula officinalis to 10.9 C (52 F) in Gomphrena globosa. Varieties were placed into three temperature response categories based on their estimated Tmin. Cold-tolerant, cold-intermediate, and cold-sensitive crops were those with estimated base temperatures of <4 C (<39 F), 4 to 7 C (39 to 45 F), and >7 C (>45 F), respectively. This temperature response categorization helps growers identify the relative tolerance of crops to low growing temperatures for energy-efficient greenhouse production. In addition, the crop timing information allows growers to more precisely produce their crops for predetermined market dates. Project #2. Plant responses to cold treatment and photoperiod varied among the species studied. A cold treatment was required to induce uniform flowering in Heuchera 'Hollywood' but not in Heuchera 'Fire Chief'. Coreopsis 'Citrine' and Salvia nemorosa 'Sensation White' flowered faster following a cold treatment. Agastache 'Cotton Candy' and the two Heuchera were day-neutral; Echinacea 'Secret Passion', Gaillardia x grandiflora 'Commotion Frenzy' and 'Gallo Dark Bicolor', Leucanthemum 'Victorian Secret', Salvia 'Sensation White', and Sedum 'Cloud Walker' and 'Mr. Goodbud' had a facultative LD response; and Coreopsis 'Citrine', Coreopsis verticillata 'Sienna Sunset', Nepeta 'Blue Dragon', Polemonium 'Snow and Sapphires', and Sedum 'Black Beauty' required LD for flowering. Nearly all of the plants had a more floriferous response when grown under the high light treatment. Under the most inductive conditions, flowering time at 20 C (68 F) ranged from 4 weeks or less (Heuchera 'Fire Chief') to 10 weeks or longer (Sedum 'Black Beauty' and 'Mr. Goodbud'). Some of these crops had been exposed to low temperatures before the experiment began and thus, cold treatment responses merit further investigation. This information enables perennial crop producers to provide the environments required for flowering so that crops can be produced in flower for their chosen market dates.

PUBLICATION INFORMATION: 2011-01-01 TO 2011-12-31
Blanchard, M.G. and E.S. Runkle. 2011. The influence of day and night temperature fluctuations on growth and flowering of annual bedding plants and greenhouse heating cost predictions. HortScience 46:599-603.

PROJECT CONTACT INFORMATION
NAME: Runkle, E.
PHONE: 517-355-5191
FAX: 517-353-0890