20 Oct 2023
USDA FNRI: Several Consequences of Growing Too Cool
Erik Runkle, Michigan State University
Discussion of the consequences of lowering greenhouse air temperature including slower rooting during propagation and longer crop production time.
Downloadable resources from completed projects are available from this page.
Evaluation of the influence of light at the same total intensity (photon flux density, or PFD) using three different types of white LEDs, combined with light from red LEDs, while keeping the blue PFD constant in kale and lettuce.
Discussion of the consequences of lowering greenhouse air temperature including slower rooting during propagation and longer crop production time.
Discussion of the specific functions of transpiration, as well as the different cultural and environmental factors in controlled environments that can influence the process.
Successfully rooting tropical foliage plants and succulents.
Successfully rooting tropical foliage plants and succulents.
Flower induction of specialty cut flowers.
Collaborative research determines how to prevent chlorosis and undesirable purple pigmentation that can sometimes develop on cuttings rooted under LED supplemental lighting.
Evaluation of the effects of four sanitizers on (A) biofilm control within mist irrigation lines, and (B) biofilm and plant growth in hydroponic lettuce cultivation.
A collection of articles from the past year by Dr. Erik Runkle from Michigan State University that deal with leaf purpling, how photosynthesis and respiration affect plant growth, and the challenges of growing vertically inside greenhouses.
FRA 2021 Runkle Purple leaves (356 KB)
FRA 2021 Runkle Maximize Pn minimize Rs (263 KB)
FRA 2021 Runkle Growing vertically (414 KB)
A collection of articles from the past year by Dr. Erik Runkle from Michigan State University that deals with plant diagnostics, propagation, height control, and quality floricultural crops.
Propagation pointers (277 KB)
Poor quality floricultural crops (272 KB)
Perennial height control (265 KB)
Indoor propagation (275 KB)
Importance of plant diagnostics (726 KB)
Heat Delay in poinsettias and how to mangage it.
See the grower articles on LED lighting and effect on plant growth:
1. Keys to Successful Seedling Production, GPN, November 2015
2. Managing Light to Improve Rooting of Cuttings, GPN, September 2016
3. Juvenility in Perennials, GPN, June 2016
4. Efficacy of Lamp Types at Controlling Flowering, GPN, February 2016
5. Red Light and Plant Growth, GPN, August 2016
6. Success with Succulents, GPN, July 2016
Keys to successful seedling production (190 KB)
Success with succulents (1169 KB)
See the two climate related articles:
1. The Boundary Layer and Its Importance, GPN, March 2016
2. VPD vs. Relative Humidity, Heidi Wollaeger & Erik Runkle, Inside Grower
The boundary layer and its importance (136 KB)
VPD versus relative humidity (147 KB)
See the grower articles on LED lighting and effect on plant growth:
1. Sole-Source Lighting In Horticulture: Microgreens Production, Joshua K. Craver and Roberto G. Lopez, Greenhouse Grower, September 2015
2. Sole-Source Lighting In Horticulture: Bedding Plant Plug Production, Joshua K. Craver and Roberto G. Lopez, Greenhouse Grower, October 2015
3. The Impact of DLI, Light Quality and Photoperiod on Bedding Plant Flowering Response, W. Garrett Owen and Roberto G. Lopez, GPN, August 2016 (Note: the title was modified)
4. Evaluating Greenhouse Supplemental Lighting For Young And Finished Plant Production, Joshua K. Craver and Roberto G. Lopez, Greenhouse Grower, November 2016
Sole-source lighting in horticulture microgreens production (4770 KB)
Evaluating greenhouse supplemental lighting for young and finshed plants (1684 KB)
Spreadsheet tools to predict time to harvest for cut flower roses.
Unas herramientas de Excel para predecir el tiempo de la cosecha de rosas de corte.
This computer decision-support tool quantifies how a change in greenhouse air temperature would affect flower timing for a range of floriculture species.
This information is helpful when growers are considering reducing greenhouse air temperature in order to save on heating fuel cost, or because they want to achieve a target flowering date by manipulating temperature.
Blueberries provide a niche crop that combine consumer interest in edible gardening with sustainability and low-care perennials.
The regeneration ability, cell division activity, auxin and cytokinin content of seedling regions and hypocotyl subsections of Watsonia lepida were studied. A total of 21 different cytokinins or conjugates were found in seedlings, with the highest cytokinin content in meristematic regions (root and shoot apical meristems). The greatest contribution to the cytokinin pool came from the biologically inactive cZRMP, suggesting that significant de novo synthesis was occurring. Five different auxins or conjugates were detected, being concentrated largely in the shoot apical meristem and leaves, IAA being the most abundant. Analysis of hypocotyl subsections (C1-C4) revealed that cell division was highest in subsection C2, although regeneration in vitro was significantly lower than in subsection C1. Anatomically, subsection C1 contains the apical meristem, and hence has meristematic cells that are developmentally plastic. In contrast, subsection C2 has cells that have recently exited the meristem and are differentiating. Despite high rates of cell division, cells.
Floral ontogeny of Brunonia australis Sm. ex R.Br. (blue pincushion) and Calandrinia sp. (not yet fully classified) was investigated by scanning electron microscopy to assist further efforts for manipulating flowering of these potential floriculture crops. This is the first work to study floral initiation and the stages of flower development for these species.
We compare crop responses to lighting with incandescent lamps with that from compact fluorescent lamps (CFLs).
Learn some basic concepts about how to maximize use of supplemental (high intensity) lighting of greenhouse crops.
This article presents research-based information on how plants respond to a rotating (cyclic) high-pressure sodium lamp to create a long photoperiod.
Now in version 2.5, the Virtual Grower greenhouse simulation software translates your structure's data to help calculate costs and make choices to be more energy efficient.
With the volatile price of fuel, finding ways to limit energy consumption in the production process of poinsettia has never been more important.
Michigan State University research examines how environmental factors - especially light - influence the rooting and growth of vegetative annual cuttings.
With the high price of fuel, many growers in cold climates have lowered their temperature setpoints to save money. However, we explain how a lower greenhouse temperature increases crop time, which can sometimes actually increase overall fuel cost.
Peak production of vegetative cuttings for bedding plants in the U.S. (November to March) occurs during the period of lowest sunlight. One option to provide more light, and therefore increase both photosynthesis and yield of cuttings, is to use highpressure sodium (HPS) lamps. The key question for growers, however, is whether the increased yield in cuttings will more than offset the cost of purchase, installation, and operation of HPS.
Light is key to producing quality crops and early flowering of long-day plants. But specifically how can you turn greenhouse lighting of spring crops into profit? The following pointers can help.
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