Floriculture Environmental and Modeling Research Progress Report –September 1991
Date 8/27/91
Title of Project Floriculture Environmental and Modeling Research at Michigan State University
Institution where work is being conducted Michigan State University
Amount of Endowment Grant$ 39,000
Covering Period 1/91 to 12/91
Anticipated Date of Project Completion/Final Report 12/93 (6/94)
Individual(s) Conducting Project:
(List Project Leader First)
Dr. John A. Biernbaum - Title Associate Professor
Telephone Number 517/353-7723
Dr. Royal D. Heins - Title Professor
William Argo, Jim Brown-Faust - Title Graduate Assistant
Floriculture Environmental and Modeling Research at Michigan State University
John A. Biernbaum, Royal D. Heins, William Argo, and Nathan Lange
Michigan State University
- A. Project Objectives:
- 1. Develop fertilization and irrigation strategies to minimize use and runoff of water and fertilizers.
- 2. Identify root media properties to maximize water and fertilizer efficiency.
- 3. Determine the effect of water quality on greenhouse crop production.
- B. Summary of Work Conducted Since 1988:
- With recirculated solution subirrigation methods of potted plants, water and fertilizer use can bedramatically reduced compared to topwatering with no loss in plant quality. With traditional watering methods
as much as 40% or more of water and fertilizer is wasted in some instances. Recirculation of water does not
lead to plant death from the rapid transfer of Pythium from inoculated to non inoculated plants although some
transfer can occur. The relationship between leaching and fertilizer concentration determines media nutrient
levels. The amount applied and wasted varies over 10 fold with different techniques. Water quality has
significant effects on root media pH, foliar residue and rooting of poinsettia cuttings. High pH and soluble salts
from alkaline water decreases rooting compared to rain water or reverse osmosis treated water. Fertilization
rates well below those currently recommended can be used to produce poinsettia stock plants of the same or
better quality than those grown with fertilizer rates recommended by fertilizer companies. The number of
waterings required to maintain impatiens hanging baskets in an outdoor area can vary by a factor of two
depending on the water holding capacity of the root media. Stopping evaporation of water from the root media
surface significantly reduces water and fertilizer use by 20 to 40% during production of Easter lily and
poinsettias. The vertical movement of nutrients to the surface layer of the root media with subirrigation and
topwatering which decreases nutrient availability and increases fertilizer requirements can be reduced or stopped
with an evaporation barrier. Post production water loss in a simulated consumer environment can be reduced
by as much as 50% for poinsettia and Easter lily with pot covers to reduce water evaporation from the media.
- C. New Information Since the Spring Report:
- Five experiments including 240 ten-inch flowering hanging baskets have been in progress since Februaryto test root media and fertilization methods that influence long term garden performance of flowering plants in
hanging baskets or other container gardens. Ten commercial root media and baskets from ten producers have
varied little in their performance and water holding ability. Fertilizer requirements have been met with resin
coated fertilizer so no additional water soluble fertilizer has been needed. This spring a $50,000 equipment
grant was awarded by the Michigan Agriculture Experiment Station for irrigation and fertilization equipment
in the research greenhouses used by Dr. Biernbaum and Heins. Over the past four months the greenhouses have
been retrofitted with nine in ground concrete reservoirs, extensive plumbing, solenoid valves and irrigation
computers so that 108 benches totaling approximately 5000 square feet can be automatically irrigated with
recirculated, pH and EC adjusted nutrient solutions. The research facilities for this project have dramatically
improved. Significant time has also been spent on analysis of data and manuscript preparation. Three oral
presentations of research results from this project were made at the annual ASHS meetings at Penn State in July.
Over the last two weeks three greenhouse fertilization experiments for the fall have been initiated.
- D. Future Plans Covered by the Endowment Grant:
- Our findings concerning evaporation of water from media under a variety of conditions must be verified.Root media properties will continue to be investigated. Work is also planned to study current root media
analysis methods including production of an educational video for training greenhouse operators and employees.
More detailed fertilizer and water budgets will be completed. A proposal for continued funding was submitted.
- E. Anticipated Benefits for Floral Industry:
- One of the most important challenges facing the floral industry is educating greenhouse operators howto irrigate and fertilize greenhouse crops with minimal water and fertilizer runoff. This research is developing
specific information needed for the transition to methods that are environmentally and economically sound.
Floriculture Environmental and Modeling Research at Michigan State University
Royal D. Heins, John A. Biernbaum, William Argo, and Nathan Lange
Michigan State University
- A. Project Objectives:
- 1. Investigate the control of stem elongation by day and night temperature.
- 2. Model the growth and development of poinsettia.
- 3. Model the growth and development of the Easter lily.
- 4. Model the growth of other floricultural plants.
- 5. Develop grower management tools from the above research.
- 6. Develop information necessary for the storage of seedlings and flowering plants.
- B. Summary of Work Conducted:
- Research in this project has resulted in the following information and concepts. Stem elongation, flower initiation,and rate of plant development are all influenced by temperature. Stem elongation increases as the difference
(DIF) between day and night temperature increases. In contrast to stem elongation, flower initiation in most plants
is influenced by temperature during either part or the entire day. Non-optimal temperatures during the night (e.g.
the poinsettia), the day (e.g. the fuchsia), or both the day and night (e.g. the chrysanthemum) delay or inhibit
flower initiation. Rate of plant development is controlled by instantaneous temperature. Total time to unfold a
leaf or develop a flower is the summation of instantaneous rates of development. Models relating plant or flower
development rate to temperature can accurately predict accumulated plant development using hourly temperature
averages. Comparing actual or predicted development with required development over time can be used as a tool
for precise timing and production of plants using a grower management tool called graphical tracking.
- C. Results to Date:
- 1. Poinsettia leaf unfolding, and therefore vegetative development, can be accurately predicted using thetemperature based leaf unfolding model:
Leaves per hour = -0.01446 + 0.001917 * Temperature - 0.000039042 * Temperature^2 - This model has been validated in greenhouse trials and shown to accurately predict leaf unfolding within ahalf leaf over a three week period after pinching under varying greenhouse conditions.
- 2. Time to flower of Thanksgiving cacti (Scblumbergera truncate) flower buds can accurately be described bythe following temperature based model:
Days to flower = (4.25 - ln(bud length))/(0.0596 + 0.008125 * Temperature) - 3. Impatiens, pansy, petunia, geranium, marigold, ageratum, salvia, and fibrous begonia seedling plugs havebeen stored without continued plant development in coolers under low temperatures for up to 6 weeks
without plant loss and subsequent delay in plant development and flowering after transplanting.
- 4. The graphical tracking model for stem elongation and height control in poinsettia has been combined withan expert system program to develop an expert system to assist growers in making height control
management decisions (DIF and growth retardants). This computer program will be tested in nine
commercial greenhouses representing over one million poinsettia plants this fall.
- 5. Leveling of Thanksgiving cacti (Schlumbergera truncate) for more uniform plant height should only beconducted after flower induction is complete to avoid vegetative pad formation. This means plants should
not be leveled until they have received at least five short days.
- D. Future Plans Covered by the Endowment Grant:
- A thesis on modeling African Violet development rates in response to light and temperature will be completedby the end of 1991. The poinsettia expert system program will be tested in commercial greenhouses and on several
crops at the MSU greenhouses. Research on storage of bedding plant plugs will continue with work on assylum,
vinca, tuberous begonia, New Guinea Impatiens, and tomato.
- E. Anticipated Benefits for Floral Industry:
- All research in this project is designed to improve reliable production of flowering potted and bedding plants.Markets, whether florist or mass markets, require plants with the correct morphological characteristics (height,
flower number, etc.) at the correct time. Delivery of plants with the right characteristics at the right time with
minimal chemical input is profitable to both growers and retailers. This research is designed to assist growers
reliably produce product at the right time within buyer specifications by developing models into grower
management tools.
