Floriculture Environmental and Modeling Research Progress Report –March 1991
Date 2/27/91
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 517/353-7728
Dr. Royal D. Heins – Title Professor
William Argo, Nathan Lange – 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:
- Comparisons of recirculated solution subirrigation methods with topwatering of potted plantsdemonstrated that water and fertilizer use could be dramatically reduced with no loss in plant quality.
Measurements of the amount of water and fertilizer wasted with traditional watering methods indicated
that 40% or more of water and fertilizer is wasted in some instances. Recirculation of water did not lead
to the rapid transfer of Pythium from inoculated to non inoculated plants. The relationship between
leaching, fertilizer concentration, and root media nutrient levels was defined and it was determined that
similar media nutrient levels could be maintained with different techniques. However, the amount applied
and wasted varied over 10 fold. Water quality had significant effect on root media pH, foliar residue and
rooting of poinsettia cuttings. High pH and soluble salts from alkaline water decreased rooting compared
to rain water or reverse osmosis treated water. Fertilization rates well below those currently recommended
produced poinsettia stock plants of the same or better quality than those grown with recommended
fertilizer rates. The number of waterings required to maintain impatiens hanging baskets in an outdoor
area was reduced in half with higher water holding root media. Stopping evaporation of water from the
root media surface significantly reduced water and fertilizer use by Easter lily and poinsettias.
- C. New Information Since the Fall Report:
- Over the past 15 months and particularly the past 6 months, our efforts have concentrated oninvestigating the effect of stopping evaporation from the root media surface of potted plants on water and
fertilizer requirements and the accumulation of soluble salts and nutrients. Soluble salt concentrations at
different positions within the pot have been measured with traditional watering methods and for plants
grown with a cover on the surface of the pot to stop evaporation. We have developed what may be a
commercially acceptable method that has significantly reduced water use and fertilizer requirements of
Easter lilies and poinsettias but not chrysanthemums. In some cases water and fertilizer use has been
reduced by 25 to 50%. The covers have also been effective at reducing water loss in post
production/consumer environments. Our results may provide some evidence for why high rates of
fertilization are commonly used for potted plants. The pot cover can also be used to increase the efficiency
of water applied with high volume drip irrigation systems.
- D. Future Plans Covered by the Endowment Grant:
- More research must be completed to verify our findings and ideas concerning evaporation of waterunder a variety of conditions. Our findings have recently been shared with other researchers so that they
can be further tested. Testing in commercial greenhouses is planned for the next year. Work is also
planned to study current root media analysis methods. Increased root media analysis to determine fertilizer
requirements is one of the keys to reducing fertilizer runoff. Work on more detailed fertilizer and water
budgets will begin this fall.
- E. Anticipated Benefits for Floral Industry:
- One of the most important challenges facing the floral industry is educating greenhouse operatorshow to irrigate and fertilize greenhouse crops with minimal water and fertilizer use and runoff. This
research is developing the information needed to make the transition from the water and fertilization
methods practiced for the last 20 years to methods that will be environmentally and economically sound.
The pot cover being developed may have immediate application in areas like California where water
supplies are limited.
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 * Temperature2 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 (Schlumbergera truncata) flower buds can be described by the followingtemperature based model:
Days to flower = (4.25 – ln(bud length))/(0.0596 + 0.008125 * Temperature) - 3. Impatiens, pansy, petunia, and geranium seedling plugs have been stored without continued plantdevelopment 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).
- 5. Leveling of Thanksgiving cacti (Schlumbergera truncata) 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:
- Research during the coming year will concentrate on development of models and grower management tools onpoinsettia, Easter lily, Thanksgiving cacti, and African Violet. Field testing in commercial greenhouses and further
development of the poinsettia expert system for height control will proceed. Experiments will continue to define
acceptable temperature, humidity, and light conditions for storage of bedding and flowering plant plugs.
- 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.
