Our current research covers a wide range of areas of importance to the floriculture industry
Ph.D. candidate Yujin Park at Michigan State University investigates how the radiation spectrum of sole-source LED lighting influences growth and development characteristics of floriculture transplants.
A new method of producing floriculture transplants is indoors using light-emitting diodes (LEDs). However, one of the challenges and opportunities of implementing this new production technique is to determine the radiation spectrum to obtain desired plant responses. The quality attributes of floriculture crops, including plant size, leaf color, growth habit, and flowering time, can all be modified by the radiation spectrum, and also plant responses can vary among plant species and cultivars.
Yujin’s Ph.D. research is investigating how different spectral and intensity combinations from blue (400-500 nm), green (500-600 nm), red (600-700), far-red (700-800 nm), and white LEDs interact to regulate photosynthesis, plant growth, and flowering responses on a broad range of floriculture crops. The results from previous experiments identified the potential benefits of including far-red radiation in the lighting spectrum, including increased seedling growth, regulation of plant size, and earlier flowering. We also learned that far-red radiation combined with a moderately high intensity of blue radiation can produce compact plants while accelerating flowering time in some species. To best utilize sole-source LED lighting technology in floriculture transplant production, this research will further generate new science-based information on the kinds of plant responses and benefits growers can achieve by managing the radiation spectrum.
Last updated: 9 May 2017
Further information: Yujin Park and Erik Runkle, Michigan State University (firstname.lastname@example.org)
M.S. candidate Allison Hurt at Michigan State University is quantifying how light (duration, intensity, and quality), carbon dioxide, and temperature (air temperature and root-zone) influence floriculture and hop young plant production, quality, and subsequent flowering.
In northern latitudes, it is not uncommon for the photosynthetic daily light integral (DLI) to be ≤5 mol·m-2·d-1 during peak young plant production, necessitating the use of supplemental lighting (SL), air and root-zone heating to stimulate callusing, reduce production time, and increase plug and liner quality. However, some growers are indicating they can reduce young plant production time with the use of low-intensity photoperiodic lighting (PL) from light-emitting diodes (LEDs). Allison’s studies will include evaluation of: greenhouse bedding plant plug production under SL from high-pressure sodium (HPS) lamps and SL and photoperiodic lighting (PL) from light-emitting diode (LED) arrays with varying light intensities, qualities, and durations; interaction of CO2 concentration and broad spectrum sole-source light intensity and its effect on plug production; greenhouse propagation of hop cuttings under varying DLIs; and greenhouse propagation of annual and perennial cuttings under varying air and root-zone temperatures. In several of these studies, plugs and liners will be transplanted into a common environment to determine if quality and subsequent flowering are influenced by the treatments received during young plant production.
Last updated: 5 May 2017
Further information: Allison Hurt and Roberto Lopez, Michigan State University (email@example.com)
Kellie Walters, a Ph.D. student at Michigan State University, is working on the production, flavor and color enhancement of leafy greens and culinary herbs in controlled environments. She is evaluating how light intensity and quality, short wavelength radiation, carbon dioxide, and temperature interact and influence leafy green and herb flavor, volatile oil content, anthocyanins, growth, and development. Additionally, she has several side projects that include 1) quantifying the impact of carrier water alkalinity and air temperature at application on the efficacy of various plant growth regulators (PGRs) including ethephon and 2) determining the photoperiodic flowering responses of several specialty crops.
The plant growth regulator (PGR) ethephon [(2-chloroethyl) phosphonic acid] breaks down to release ethylene (C2H4) and can be sprayed on floriculture crops to reduce cell elongation, inhibit internode elongation, reduce apical dominance, increase lateral branching, and abort flower buds and flowers. However, the efficacy of ethephon applications is influenced by a variety of environmental and cultural factors. For example, As pH or ambient temperature increases, ethephon efficacy decreases. This is due to ethephon breaking down into ethylene more quickly before it is absorbed by the plant. Since carrier water alkalinity affects solution pH, Kellie is quantifying how ethephon efficacy is influenced by carrier water alkalinity and air temperature at application. With increased efficacy comes the potential for lower chemical inputs, increased uniformity, and higher quality plants. Kellie is also determining the photoperiodic flowering responses of several foliage annual plants, herbs, and hop vines. Growers are increasingly incorporating foliage annuals into mixed combination planters due to their brightly colored or patterned leaves. However, the flowers of these foliage annuals are often unattractive and stall the desired vegetative growth. Therefore, our goal is to provide photoperiodic lighting recommendations to prevent flowering in foliage crops and herbs and enhance cone production of hop vines grown in controlled environments.
Last updated: 5 May 2017
Further information: Kellie Walters, and Roberto Lopez, Michigan State University (firstname.lastname@example.org)
Joshua Craver is a Ph.D. candidate at Purdue University working with Roberto Lopez on alternative methods for the production and tracking of bedding plant seedlings.
Indoor production of young bedding plants using sole-source lighting (SSL) has been proposed to overcome lighting challenges in northern latitudes during late winter and early spring. Joshua’s Ph.D. research is focused on determining optimal CO2 concentrations, light qualities, and light intensities for the production of bedding plant plugs in a SSL environment. Specifically, he is evaluating how different ratios of red and blue light interact with elevated CO2 concentrations, and whether manipulating these environmental factors may benefit plug quality or hasten the time to a finished crop. Additionally, he is evaluating the use of automated and non-invasive imaging using fluorescence to estimate leaf area and track the growth rate of entire plug trays, with potential use in the bedding plant industry as a means of efficient and non-destructive monitoring. Information gathered from both of these projects will provide recommendations on how to optimize and track the production of bedding plant seedlings under SSL as well as establish a scientific understanding of how specialty floriculture crop production may be further improved under controlled-environment conditions.
Last updated: 4 May 2017
Further information: Joshua Craver and Roberto Lopez, Michigan State University (email@example.com)
M.S. student Y. Ulrich Adegbola at the University of Florida is working to assist growers by analyzing plant cutting transplant efficiency there is potential to decrease production cost and increase profit margin.
Young plant producers transplant over 25 million cuttings in a year. Transplanting unrooted cuttings is an important process in the production of rooted liners. Dr. Fisher and Ulrich are working to (1) benchmark labor productivity for transplanting cuttings, and (2) identify the key factors that affect efficiency between businesses and workers. By improving the efficiency of transplanting cuttings there is potential to decrease production cost for young plant growers. Ulrich is originally from Benin, Africa and can speak many languages. He has a B.S. in Agriculture Economics from the University of Florida and is pursuing a M.S. in Agriculture Economics. His career aspiration is to be an economic analyst for the agriculture industry.
ASHS 2016 Presentation
Last updated: 8 Oct 2016
Further information: Y. Ulrich Adegbola and Dr. Paul Fisher, University of Florida (firstname.lastname@example.org; email@example.com)
Ph.D. student Erin Yafuso at the University of Florida is working to assist growers by identifying the best ways to supply oxygen to plants roots.
Producing a healthy crop is anchored in the roots of a plant. Dr. Fisher and Erin are studying the relationship between water to oxygen and effect on rooting in container-propagated plants. We will focus on (1) evaluating a technology to super-saturate oxygen in irrigation water (2) varying substrate porosity or moisture level and (3) modeling the supply of water to oxygen in the container plant system. Erin will also develop an entry-level water-training program that will assist the trainer and trainee. Erin comes from Hawaii with a B.S. and M.S. degrees from the University of Hawaii at Manoa in Molecular Biology, she would like to pursue a career in higher education.
ASHS 2016 Presentation
Last updated: 8 Oct 2016
Further information: Erin Yafuso and Dr. Paul Fisher, University of Florida (firstname.lastname@example.org; email@example.com)
Along with his research, M.S. student, George Grant is using graphical tracking to schedule poinsettias for the National Poinsettia Trials at the University of Florida.
The use of plant growth regulators (PGRs) provides growers in the greenhouse and nursery industry a variety of economic benefits when used correctly. PGRs are primarily applied by foliage sprays or drenches that commonly leach out of the container when over irrigated. PGR leachate and runoff can negatively affect irrigation water, neighboring crops, and the environment if unmanaged. Dr. Paul Fisher and his M.S. student, George Grant are testing granular activated carbon (GAC) and ozone to effectively filter out Paclobutrazol, the active ingredient found in products like Bonzi, Piccolo, and Paczol. The information gained from this research can help growers who recirculate their irrigation water with a greenhouse or catch pond system form strategies to prevent PGR contamination problems. George is also experimenting with sanitation procedures for removing Paclobutrazol from containers, plug trays, and liners. Reusing container supplies can also be cost effective for grower operations, however, even a small amount of PGR residue left on a container can cause unwanted effects to crop growth. George strives for a Ph.D. in Environmental Horticulture as well as a career in sustaining water quality for the public health and the environment.
ASHS 2016 Presentation
Last updated: 7 Oct 2016
Further information: George Grant and Dr. Paul Fisher, University of Florida (firstname.lastname@example.org; email@example.com)
Ryan Dickson is a Ph.D. candidate at the University of Florida focused on understanding how floriculture and vegetable plant species interact with fertilizer solutions to affect pH.
Fertilizer nutrient solubility is largely influenced by container substrate-pH, and therefore maintaining pH within an optimal range during production is necessary for adequate nutrient availability and healthy plant growth. Floriculture crop species have different effects on pH even when supplied the same fertilizer, making it difficult to manage pH and prevent crop nutritional disorders, such as iron and manganese toxicity or deficiency, with sensitive species grown in the same production zone. Ph.D. candidate Ryan Dickson is working to understand how plant species differ in pH effect by investigating the underlying plant physiology behind nutrient uptake and root acidity or basicity. He is also looking at species differences in ammonium-N and nitrate-N uptake preference as well as adaptive root responses to phosphorus and iron deficiency as possible explanations for why important floriculture species such as Pelargonium rapidly decrease pH in container production.
Ryan is updating the Fertilizer pH Calculator in www.BackPocketGrower.com, a grower resource online and mobile phone app, by including pH effects from a wider range of floriculture and vegetable crop species. The Fertilizer pH Calculator is a tool that balances acidic and basic factors in production, including media components, fertilizer nutrient concentrations, plant species, and water alkalinity, to maintain a stable root zone pH and prevent pH drift during production. Ryan’s goal is to continue working with growers at optimizing fertilizer and pH management strategies for floriculture and vegetable container crops.
Last updated: 3 Sep 2015
Further information: Ryan Dickson and Paul Fisher, University of Florida (firstname.lastname@example.org; email@example.com)
M.S. candidate QiuXia Chen at Michigan State University is evaluating hybridized petunia for genetic traits linked to desirable crop timing and quality traits.
Conventional breeding techniques have been slow to improve current cultivars and varieties, leading to a desire to develop genomic tools to enhance breeding programs. Molecular breeding techniques have proven to be successful for many diverse horticultural crops such as apple, soybean, cucumber, etc. As energy and labor costs increases, we can utilize genetic markers to develop improved varieties that performs in suboptimal conditions. QiuXia is using genetic linkage maps for various F7 recombinant inbred line populations to identify potential quantitative trait loci (QTLs) linked to desirable quality traits such as early flowering and increased branching. In addition, she will identify potential QTLs linked to traits related to field performance such as flower intensity. These QTLs will be mapped to the genomic scaffolds to identify candidate genes underlying the QTLs.
Last updated: 22 Jul 2015
Further information: Ryan Warner and QiuXia Chen, Michigan State University (firstname.lastname@example.org)
Current practices in the propagation of vegetative annuals.
1. Quantifying the amount of water applied to cuttings in commercial propagation greenhouses. The results showed that the calculated amount of water applied per square foot over the 10 day propagation period was 0.4 to 5.7 liters per square foot for vegetative annuals while for geraniums it was 0.30 to 11.1 liters per square foot.
2. Using a propagation weather station to measure propagation environment, mist volume applied, and leachate in commercial situations.
3. Effect of water and air content of the propagation media on adventitious root formation. Our experiments showed that rooting was best for poinsettias at an 86% saturation level while 94% was optimal for Osteospermum.
Developing a functional model for mist management in propagation
1. Develop an evapotranspiration model based on potential water uptake, stomatal behavior and environmental measurements to predict water demand for cuttings in propagation.
2. Develop a commercially viable system to make mist application decisions based on the cutting water demand as determined by the evapotranspiration model.
For more information, contact Jim Faust (email@example.com) or Jeremy Crook (firstname.lastname@example.org)
Last updated: 1 Nov 2013
Further information: Jim Faust and Jeremy Crook (Clemson University
Toning can be defined as the resistance to forces acting to crush stems or tear leaves. While this has not been quantified, it is being used by growers via empirical observations to evaluate cuttings for postharvest and propagation performance.
In general, drought stress, low humidity and moderate nitrogen levels produces 'toned' plants while excess water, humidity and nitrogen produces ‘soft’ plants; however, providing this environment can be challenging on the scale of large commercial cutting production. Alternatively, calcium nutrition has been utilized to promote post-harvest performance in many horticultural products, but on to limited extent in the context of unrooted cutting production. The current project is aimed at addressing the following issues with the use of geranium and poinsettia as model species.
1. Can we quantify degree of toning? Currently mechanical properties of leaves are being assessed using a texture analyzer.
2. Can foliar calcium treatments influence the toning of a cutting? If so, what mechanical and physiological properties of cuttings important in postharvest durability are influenced?
3. What is the influence of pre-harvest foliar calcium treatments on cutting performance in the propagation environment?
Further information: James E. Faust (email@example.com) and Uttara Samarakoon (firstname.lastname@example.org)
Last updated: 30 Oct 2013
Further information: James E. Faust and Uttara Samarakoon (Clemson University)
Biological solutions to common production problems are welcomed by growers and customers as our society has higher expectations for sustainability. A relatively new mycorrhizal-like fungus, Piriformospora indica, has been shown to improve overall plant growth and disease resistance of various plant species. This organism shows promise to affect several plant responses of high importance to the floriculture industry including: increased rooting in propagation, increased resistance to root pathogens and increased nutrient uptake.
In our experiments, P. indica inoculation in propagation media produced varied results. Euphorbia 'Supreme Bright Red', Osteospermum, and Lantana showed a significant increase in wet root mass by inoculation with P. indica. In contrast, Euphorbia 'Champion Fire' and 'Premium White', Crossandra, and Dahlia did not significantly respond to treatments in terms of wet root mass.
P. indica has shown potential to be a preventative biological fungicide to highly pathogenic Phytophthora nicotianae on Petunia species. Common commercial biological products were also compared alongside P. indica. The highest percentage of P. indica incorporation (30% v/v) delayed the onset of disease symptoms on all varieties of Petunia (Figure 1). P. indica applied at the lower rates (10 &;20% v/v), Companion, Rootshield, and Rootshield Plus were significantly better, in terms of disease severity, than the untreated control, although not as good as the 30% rate of P. indica.
It has been documented that P. indica can help to increase nutrient uptake when the nutrients are applied at low concentrations in the growing media. Floriculture crops grown with low (10 ppm) nitrogen and normal rates of the other essential nutrients showed a consistent increase in flower number, flower date, and shoot fresh and dry weight when the plants were inoculated with P. indica. Petunia and Calibrachoa grown without phosphorus but with normal rates of the other essential nutrients did not show treatment effects of flower number, flower date, and shoot fresh and dry weight when the plants were inoculated with P .indica. SunPatiens inoculated with P. indica showed reduced flower number and fresh shoot weight.
For more information contact: Jim Faust (email@example.com) or Allison Justice (firstname.lastname@example.org)
Last updated: 30 Oct 2013
Further information: Jim Faust and Allison Justice (Clemson University)