2019 Kansas State University Industrial Hemp CBD Variety Trial
Professor DeBacco
Research Article
Griffin, J., Shelton, M. J., Wilson, C., & Myers, T. (2020). 2019 Kansas State University Industrial Hemp CBD Variety Trial. Kansas Agricultural Experiment Station Research Reports, 6(1), 1.
https://newprairiepress.org/kaesrr/vol6/iss1/1/
Outdoor and High Tunnel
While both technically fall under the category of outdoor production these are different environments.
Outdoor Grown = Outside with full exposure to the elements. In this study the plants were grown in containers and on weed fabric, (to help fertilizer trials) but other than this it represented the typical outdoor field conditions.
High Tunnel = This is a structure that looks like a greenhouse and while it has plastic covering it lacks addition equipment to modify the environment. (Ex. Heaters)
Study Objectives
Evaluate commercially available varieties of CBD hemp in south-central Kansas grown in containers outdoors or inside of a high tunnel.
To test whether a covered high tunnel could effectively reduce pollination of the plants within.
Plant Material and Substrate Used
On June 17, 2019, clones (from rooted cuttings) of each variety (Table 1) were potted from 1 gal plastic pots into 7 gal plastic pots or into 7 gal fabric bags.
Outdoor and High Tunnel Layout
Plants were then placed outdoors on a container production pad or in an adjacent high tunnel.
Outdoor Plants:
Placed on a black ground cloth and fastened to a trellis wire to prevent blowover.
Spacing: Plants were in rows 6-ft apart with 4-ft spacing in the row.
High Tunnel (Size 20ft. X 99ft.) plants:
Placed on same black fabric ground cloth on the soil surface as outdoor plants
Covering: Clear polyethylene covered the top of the high tunnel with 30% white shade cloth over that.
Sidewalls: The sidewalls and end walls were covered with insect exclusion screen to prevent insect pollinators from easily entering the high tunnel.
Spacing: Plants were spaced on a 4 ft × 4 ft grid pattern.
Influence of Container Type
There was no influence of container type on any of the growth data collected (data not shown) so data presented are averaged over container type
Plastic pots vs Fiber bags
Number of Colas
The number of primary colas per plant was strongly influenced by the high tunnel environment in all varieties.
Both Cherry and Super CBD were only influenced by the high tunnel, whereas, the other varieties were also influenced by the fertilizer form or an interaction was observed.
All Cherry plants in the outdoor plot had completely senesced by experiment termination, while the high tunnel plants were alive and appeared as expected at harvest time.
Conventional fertilizer increased cola number in ACDC, Otto II Stout, and The Wife.
There was greater than a 100% increase in cola number in high tunnel The Wife plants with conventional compared to organic fertilizer (68.6 compared to 32.6, respectively).
Cannabinoid Production
Outdoor Plants:
Overall low cannabinoid production due to…
Not unexpected due to a fiber and dual-purpose variety trial plot approximately 400 ft north of the high tunnel and outdoor CBD variety plot. High rates of pollination were anticipated.
The Wife had highest CBD content of 4.6%
This variety also appeared to have the most well-developed female flower buds and lowest quantity of seed.
THC concentration was well below the 0.3% threshold for industrial hemp in all varieties.
Study Objectives Revisited
Evaluate commercially available varieties of CBD hemp in south-central Kansas grown in containers outdoors or inside of a high tunnel.
Container type did not impact plants to any measurable degree
The Wife and Cherry varieties produced the greatest amount of CBD in both the outdoor and high tunnel environments
High tunnel grown plants produced greater CBD % than outdoor plants due to reduced amount of pollination.
To test whether a covered high tunnel could effectively reduce pollination of the plants within.
While some seed development was observed in the high tunnel, there was much less pollination compared to plants in the outdoor plot.
Summary of Data
Outdoor
Organic fertilizers should be used with caution due to the potential for increased nitrogen deficiency
High Tunnel
Would be recommended if the chance for pollination exists in a particular field (make sure to be using insect netting on sidewalls)
Scout for Russet mites and Army worms
General
The Wife and Cherry varieties should be considered if % CBD is the main goal while still keeping THC levels below 0.3%.
Using a high tunnel will likely increase yields, the question to the growers is can the cost of the high tunnel be justified by the difference?
Link to Lecture Slides:
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